Home Biomedical and therapeutic potential of marine-derived Pseudomonas sp. strain AHG22 exopolysaccharide: A novel bioactive microbial metabolite
Article Open Access

Biomedical and therapeutic potential of marine-derived Pseudomonas sp. strain AHG22 exopolysaccharide: A novel bioactive microbial metabolite

  • Ghfren S. Aloraini , Mona Othman I. Albureikan , Aisha M. A. Shahlol , Taghreed Shamrani , Hussam Daghistani , Mohammad El-Nablaway , Nagwa A. Tharwat , Ahmed M. Elazzazy , Ahmed F. Basyony and Ahmed Ghareeb EMAIL logo
Published/Copyright: May 8, 2024
Download Article (PDF)
Become an author with De Gruyter Brill
Submit Manuscript Author Information
REVIEWS ON ADVANCED MATERIALS SCIENCE
From the journal REVIEWS ON ADVANCED MATERIALS SCIENCE Volume 63 Issue 1

Abstract

Microbial exopolysaccharides (EPSs) are gaining interest as alternatives to chemical antioxidants and pharmaceuticals. This study mines the promising biomedical and antimicrobial potential of a marine bacterium, a prolific EPS producer, isolated from the Red Sea. Pseudomonas sp. strain AHG22 generated an EPS weighing 6.98 g·L−1, coded EPSF8, subjected to FT-IR and HPLC chemical analysis. EPSF8 was then investigated for antioxidant assessment by 2,2-diphenyl-1-picrylhydrazyl (DPPH), H2O2, ABTS˙ + , nitric oxide, total antioxidant capacity (TAC), and ferric reducing antioxidant power (FRAP). EPSF8 had an IC50 of 46.99 μg·mL−1 in the DPPH antioxidant assay and antioxidant capacities of 219.45 μg·mg−1 ascorbic acid equivalent (AAE) in the TAC assay and 54.15 μg·mg−1 AAE in the FRAP assay. The in vitro anti-inflammatory effect of EPSF8 was tested against 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) enzymes and compared with the drugs ibuprofen and celecoxib used as controls. The IC50 values of 5-LOX, COX-2, ibuprofen, and celecoxib were found to be 14.82, 15.49, 1.5, and 0.28 μg·mL−1, respectively. Additionally, EPSF8 revealed antidiabetic activity toward α-amylase and α-glucosidase, and the IC50 values were 93.1 and 127.28 μg·mL−1, compared to those of acarbose (50.93 and 4.13 μg·mL−1, respectively). Anti-obesity activity of EPSF8 by lipase inhibition revealed IC50 = 56.12 μg·mL−1 compared to orlistat (IC50 = 20.08 μg·mL−1) as a control. EPSF8 displayed antibiofilm and bactericidal activity against Gram-positive (G +ve) and Gram-negative (G −ve) ATCC pathogenic bacterial strains. It had a minimum bactericidal concentration/minimum inhibitory concentration ratio ≤2, indicating a broad bactericidal spectrum. Furthermore, EPSF8 is evidenced to have a promising anti-butyrylcholinesterase activity for the control of Alzheimer’s disease. The findings of the present analysis suggest that the isolated Pseudomonas sp. strain AHG22 EPS can potentially be explored as a promising green therapeutic compound.

Keywords: antioxidant; anti-inflammatory; antidiabetic; anti-obesity; antibiofilm; anti-Alzheimer

1 Introduction

In recent years, there has been growing scholarly interest in meticulously examining and discerning microorganisms and their exopolysaccharides (EPSs) as plausible and invaluable biomedical products [1]. Utilizing microbial EPSs in the pharmaceutical sector presents a promising avenue for exploration, offering a viable alternative to chemical antioxidants. This alternative is particularly appealing due to the adverse long-term effects and safety concerns associated with conventional chemical antioxidants [2].

Several studies have demonstrated the ability of specific polysaccharides to enhance cellular defense mechanisms while concurrently mitigating the deleterious effects induced by reactive oxygen species (ROS) [3]. These polysaccharides have been found to impede the accumulation of free radicals, thereby preventing lipid peroxidation [4]. Expanded polysaccharides (EPSs) are strategically utilized as efficacious radical scavengers to safeguard the body from the deleterious effects of free radicals, which have been implicated in the etiology of diverse chronic health conditions [5]. Presently, there are recent reports of the antioxidant capacities of EPS, including those of marine origin, Bacillus subtilis [6], Bacillus cereus [7], Kocuria sp. [8] and Bacillus velezensis [9] and Bacillus licheniformis [10].

Marine microorganisms have also been reported to generate immunomodulatory extracellular polysaccharides (EPSs). These EPSs have been shown to influence the immune response in various ways [11]. For instance, an EPS known as EPS2E1 was isolated from the marine bacterium Halomonas sp. and showed intense immune-enhancing action by primarily stimulating the mitogen-activated protein kinase and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways [12]. Sphingobactan, an alpha-mannan EPS extracted from Arctic Sphingobacterium sp., considerably dwindled the amount of nitric oxide (NO) produced by LPS-activated macrophages [13]. Chatterjee et al. hypothesized that sphingobactan might activate macrophages’ in vitro anti-inflammatory activities.

The significance of EPS in tackling infectious diseases has been recently investigated. Extensive reports have demonstrated that marine microbial EPS possesses remarkable immune-modulating and antiviral properties, exhibiting promising potential in inhibiting specific strains of influenza viruses and bacteria. A marine polysaccharide was explored by Abdalla et al. to have strong antibacterial properties and effectively inhibit uropathogenic Escherichia coli (UPEC) [14,15]. This could be an alternative, antibiotic-free treatment for urinary tract infections [16]. Similarly, Wu et al. found that an EPS (EPS273) synthesized P. stutzeri 273 had an anti-biofilm effect and could inhibit Pseudomonas aeruginosa [17].

Carbohydrate metabolism involves two primary glycosidases: α-glucosidase and α-amylase. The inhibitors of these enzymes are used in the treatment of, notably, type 2 diabetes and obesity [18,19]. Microbes generate desirable glycosidase-inhibiting compounds. These compounds have immense potential as pharmaceuticals and dietary supplements. Actinoplanes sp.’s acarbose, an inhibitor of glucosidase, is highly effective in treating type 2 diabetes [20]. This marketed medication class, though adequate for treating type 2 diabetes, has significant limitations as a medication. It can cause side effects like abdominal discomfort, diarrhea, and flatulence and has restrictions, including high costs and low patient compliance. This indicates the demand for innovative classes of glucosidases derived from microorganisms with greater compliance, socioeconomic benefits, and safety prospects [21].

While microbial EPS has shown promise as an alternative to synthetic antioxidants and antibiotics, the biomedical potential of Pseudomonas EPS is relatively underexplored. We hypothesize that marine Pseudomonas sp. strain AHG22’s EPS exhibits significant bioactivity supporting pharmaceutical applications. The present investigation comprehensively represents the isolation and identification process of Pseudomonas sp. strain AHG22 obtained from the Red Sea, employing morphological, biochemical, and 16S rRNA techniques. In addition to producing EPS, this study also examines its chemical composition and analysis. Finally, it sheds light on the extensive in vitro pharmacological profiling of the metabolite, including antioxidant, anti-inflammatory, anti-Alzheimer, metabolic, antimicrobial, and antibiofilm assays.

2 Materials and methods

2.1 Isolation and sampling of bacteria from the Red Sea

A 500 mL seawater sample was collected from the western coastline of the Red Sea, Saudi Arabia, in March 2023. The sample was gathered from the sea surface using a sterile container and transported to the lab in an insulated container at 4°C. In the lab, serial dilution and marine media were made by adding the following ingredients: glucose (20 g), CaCO3 (1.0 g), NH4NO3 (0.8 g), KH2PO4 (0.05 g), K2HPO4 (0.6 g), MgSO4·7H2O (0.05 g), MnSO4·4H2O (0.1 g), and yeast extract (0.1 g) were mixed in750 mL of seawater to produce 1 L [22].

2.1.1 Selection and identification of bacterial strains

Bacterial strains were selected based on their culture growth [23] and their maximum (EPSs) synthesis rate. A 16S rRNA sequence was performed for genetic classification, and phylogenetic analysis was conducted: The forward primer was 5′-TCCGTAGGTGAACTTTGCGG 3′, and the reverse primer was 5′-TCCTCCGCTTATTGATATGC-3′ [24]. The gained DNA sequence was compared to the GenBank database at the NCBI using the BLAST tool. An alignment was then performed to determine how closely the sequence of the isolate resembled those in the database.

2.2 Production and fractional precipitation of the EPS

The promising strain F8 was chosen for EPS production based on culture, physiology, and biochemical characteristics. The bacterial isolate F8 was cultured in a broth containing yeast extract (2 g·L−1), sucrose (20 g·L−1), and peptone (4 g·L−1). These constituents were put into 750 mL of seawater and then made up to 1 L. After growing, the bacteria were separated by spinning at 4,000 rpm at 4°C for 30 min. TCA (10%) was incorporated to eliminate protein, and the mixture was placed at 4°C and left overnight. The solution was spun again for 20 min at 5,000 rpm, and the liquid on top was kept separate. The pH of the liquid supernatant was then adjusted to 7 using NaOH solution. After that, the supernatant was precipitated with cold C2H5OH and centrifuged. The residue was re-dissolved, dialyzed for 72 h, and fractionally precipitated with four successive increasing volumes of C2H5OH [25]. Then, the UV absorption spectra within the wavelength range of 200–800 nm were analyzed to ascertain the presence of proteins and nucleic acids [26].

2.3 Characterization of EPS using FT-IR, colorimetric, and HPLC techniques

FTIR spectra were examined by mixing 2.0 mg of EPS with 200 mg of KBr pellets, and the mixture was subjected to FTIR spectroscopy using a Bruker Vector 22 Spectrophotometer [27]. Uronic acid was detected in the sample using the colorimetric technique elucidated by Filisetti-Cozzi and Carpita, in which EPS was diluted with 2 mL of concentrated H2SO4, boiled at 100°C for 20 min, cooled, and then 150 mL of m-hydroxy diphenyl was added, and the absorbance of the mixture was measured at 520 nm after 60 min [28]. The sulfate content was quantified using Garrido’s method, in which 5 mg of EPS was hydrolyzed with 5 mL of 88% formic acid at 105℃ for 5 h. After drying, 10 mg of BaCl2 was dissolved in a small amount of H2O, Tween 20 (20 mL) was supplemented, and the total volume was brought up to 100 mL in a flask. To a 10 mL hydrolysate, 1 mL of 0.3 N HCl and 1 mL of the BaCl2-Tween 20 reagent were added. After mixing and standing for 15 min, the optical density was read at 500 nm [29].

The technique outlined by Randall et al. [30] was applied to explore the monosaccharide composition. EPS was first hydrolyzed with 2 M CF3COOH at 120°C for 120 min. The resulting solution was subjected to dilution in CH3OH and subsequent vacuum drying. The ensuing residue was solubilized in H2O and examined using an Aminex carbohydrate HP-87C column (300 × 7.8 mm) with a flow rate of 0.5 mL·min−1, and H2O was the eluent.

The UV absorption spectra within the wavelength range of 200–800 nm were analyzed to detect proteins and nucleic acids [26].

2.4 Antioxidant evaluation of the EPS

2.4.1 DPPH assay

The antioxidant activity of the EPS was examined at different concentrations (1.9, 3.9, 7.8, 15.6, 31.2, 62.5, 125, 250, 500, and 1,000 μg·mL−1) using the method outlined by Brand-Williams et al. [31], where 0.1 mM solution of 1,1- diphenyl-2-picryl hydrazyl (DPPH) in C2H5OH was prepared. Then, 1 mL of this solution was added to 3 mL of the EPS sample in C2H5OH at different concentrations (1.9–1,000 μg·mL−1). The mixture was shaken and left at room temperature for 30 min. Absorbance was detected at 517 nm using a spectrophotometer (UV-VIS milton roy). The reference standard used in the experiment was ascorbic acid, and the testing process was conducted in triplicate:

DPPH scavenging inhibition ( % ) = ( Ab 517 of control − Ab 517 of sample / Ab 517 of control ) × 100 .

2.4.2 H2O2 assay

The ability of the EPS to remove H2O2 was assessed, according to Ruch et al. EPS was prepared at different concentrations (100, 300, 500, and 1,000 μg·mL−1) in 0.1 M phosphate buffer (pH = 7.4). EPS solutions were incubated with 43 mM H2O2 in phosphate buffer in the dark at room temperature. The absorption at 230 nm was measured during 15–60 min to assess changes over time [32]:

H 2 O 2 scavenging ( % ) = ( Ab 230 of control – Ab 230 of sample / Ab 230 of control ) × 100 .

2.4.3 ABTS˙+ assay

The extracted EPS was assessed at different concentrations (100–1,000 µg·mL−1) following the methodology described by Miller and Rice-Evans. The ABTS reactive cation scavenging capacity was assessed by quantifying the absorbance at a wavelength of 734 nm [33]:

ABTS ˙ + scavenging activity ( % ) = [ 1 − ( Ab sample / Ab control ) ] × 100 .

2.4.4 Nitric oxide (NO) assay

NO scavenging was carried out, according to Balakrishnan et al. [34]. The reaction mixture contained 0.5 mL of PBS and 2 mL of 10 mM sodium nitroprusside (pH = 7.4). About 0.5 mL of 100–1,000 µg·mL−1 EPS was added to the reaction mixture, which was then shaken and incubated for 2 h at room temperature. A 0.5 mL sample of the combination was mixed with 1 mL of 0.33% sulfanilic acid in a separate test tube and kept at 37℃ for 5 min. Then, 1 mL of 0.1% naphthalene diamine chloride was added and incubated at room temperature for 30 min. The absorbance was recorded at 540 nm [34]:

NO ( % ) = [ 100 − ( Ab sample − Ab blank ) × 100 ] / Ab Control .

2.4.5 Total antioxidant (TAC) assay

EPS evaluation was conducted using spectrophotometric analysis based on the phosphomolybdenum technique. About 1 mL of 0.5 mg·mL−1 EPS was mixed with 3 mL of reagent solution containing 0.6 M H2SO4, 28 mM NaH2PO4, and 4 mM ammonium molybdate. A blank was prepared with only 4 mL of the reagent solution. The samples and blank were heated at 95°C for 150 min and then cooled to room temperature [35]. The absorbance at a wavelength of 630 nm was quantified using a microtiter plate reader (Biotek ELX800, VT, USA). The values were quantified using the ascorbic acid equivalent (AAE) unit, expressed in µg·mg−1 of EPSF8, as described by Lahmass et al. [36].

2.4.6 Ferric reducing antioxidant power (FRAP) assay

To examine the influence of solvent polarity on the total reducing power of the EPS, the potassium ferricyanide (K3Fe(CN)6) and trichloroacetic acid (C2HCl3O2) method was used as described by Benzie and Strain [37] with certain adjustments and modifications to accommodate the microplate technique, as outlined by Athamena et al. [38]. In brief, 40 mL of EPS was added to a tube with 50 mL of 0.2 M Na2HPO4 buffer, 50 mL of 1% K3Fe(CN)6, and 50 mL of 10% CCl3COOH acid. The mixture was centrifuged at 3,000 rpm for 10 min. Then, 166.66 mL of the supernatant and 33.3 mL of 1% FeCl3 were added to wells. The readings were recorded at 630 nm via a microtiter plate reader (Biotek ELX800; Biotek, Winooski, VT, USA). DMSO was employed as the negative control in the experimental setup, while ascorbic acid at 1 mg·mL−1 was the positive control. The outcomes were quantified regarding AAE µg·mg−1 of the sample.

2.5 Anti-inflammatory evaluation of the ESP

2.5.1 In vitro inhibition of 5-lipoxygenase (5-LOX) activity

LOX solution (1,000 U·mL−1, pH = 9) was mixed with varying concentrations of EPS (0.98–125 μg·mL−1) for 15 min at room temperature. After adding linoleic acid, the reaction was measured by monitoring absorption at 234 nm using a microplate reader (BIOTEK, Winooski, VT, USA) [39] with ibuprofen as the positive control:

5 - LOX Inhibition ( % ) = ( 1 – Ab Sample 234 / Ab Control 234 ) × 100 .

2.5.2 In vitro inhibition of cyclooxygenase (COX-2) activity

The efficacy of EPS in alleviating inflammation was assessed through its capacity to inhibit the COX-2 enzyme (0.98–125 µg·mL−1) compared to the reference standard (0.98–125 µg·mL−1 Celecoxib) following a methodology outlined by Amessis-Ouchemoukh et al., which depends on the oxidation of TMPD by arachidonic acid in the presence of COX-2 enzyme [40]. The inhibitory activity percentage of the EPS against the COX-2 enzyme was determined by measuring absorbance at 611 nm using a microplate reader:

COX- 2 inhibition ( % ) = ( 1 − Ab sample 611 / Ab control 611 ) × 100 .

2.6 Butyrylcholinesterase (BChE) inhibition assay

BChE inhibition assay was performed using butyrylcholine iodide as a substrate, based on a colorimetric method outlined by Gorun et al. [41], and final concentrations (0.195–100 μg·mL−1) for the tested EPS were compared with those of rivastigmine control drug (0.195–100 μg·mL−1). BChE was dissolved in 20 mM sodium phosphate buffer (pH = 7.6) to make a 3.47 unit·mL−1 stock solution and stored at −80°C. EPS was prepared by dissolving compounds to 100 μg·mL−1 in phosphate buffer (pH = 7.6). Solutions were diluted to various concentrations in phosphate buffer before experiments. The 5,5′-dithio-bis-(2-nitrobenzoic acid)–phosphate–ethanol reagent was prepared by dissolving DTNB in ethanol and adding water and phosphate buffer (pH = 7.6) [41]. The absorption was recorded at 405 nm on a microplate reader:

BChE inhibition ( % ) = { ( Control 405 − Sample 405 ) / Control 405 } × 100 .

2.7 Anti-obesity assessment

Anti-lipase inhibition assay was performed using p-nitrophenyl butyrate (PNPB) as the substrate for measuring antilipase activity, and lipase stock solutions (1 mg·mL−1) were made in a 0.1 mM K3PO4 buffer (pH = 6.0) and kept at −20°C. EPS (1.9, 3.9, 7.8, 15.6, 31.2, 62.5, 125, 250, 500 and 1,000 μg·mL−1) and orlistat of similar concentrations were pre-incubated with lipase for 60 min at 30°C in 0.1 mM KH2PO4 buffer) pH = 7.2 in order to determine their lipase inhibitory activity. Then, at a final volume of 100 μL, 0.1 μL of PNPB was added as a substrate to start the reaction. Using a Biosystem 310-plus UV-visible spectrophotometer, the reaction’s release of p-nitrophenol was quantified at 405 nm after being incubated at 30°C for 5 min [42]:

Lipase inhibition ( % ) = 100 – [ ( B – b ) / ( A – a ) × 100 ] ,

where A is the absorbance of lipase without an inhibitor, a is the absorbance of the negative control (DMSO) without an inhibitor/lipase, B is the absorbance of lipase with an inhibitor, b is the absorbance of the negative control (DMSO) with an inhibitor, without lipase, and DMSO was the negative control, and its activity was examined.

2.8 Antidiabetic assessment

2.8.1 In vitro α-amylase inhibition assay

The α-amylase inhibition assay utilized the 3,5-dinitrosalicylic acid (DNSA) method described by Wickramaratne et al. [43]. In this assay, EPS was tested at concentrations ranging from 1.95 to 1,000 μg·mL−1 and compared to an acarbose standard control at the same concentrations (1.95–1,000 μg·mL−1). About 200 μL of α-amylase solution was combined with 200 μL of EPS and held at 30°C for 10 min. Then, 200 μL of 1% starch solution was added and incubated for 3 min. The reaction was terminated by adding 200 μL of DNSA reagent and boiling for 10 min at 85–90°C. The mixture was cooled to room temperature and diluted with 5 mL of H2O [43]. The absorbance was recorded at 540 nm using a Biosystem 310 spectrophotometer. The IC50 values were obtained from the graph by plotting the percentage of α-amylase inhibition against the EPS concentration:

α-amylase inhibition ( % ) = ( Abs control − Abs Sample ) × 100 / Abs control .

2.8.2 In vitro α-glucosidase inhibition assay

The α-glucosidase inhibition assay followed Pistia Brueggeman and Hollingsworth’s method. EPS at concentrations ranging from 1.95 to 1,000 μg·mL−1 was compared to an acarbose control at the same concentrations. EPS (1.97–1,000 μg·mL−1) was incubated with α-glucosidase enzyme solution (1 U·mL−1) for 20 min. After 20 min, 1 M pNPG substrate was added and incubated for 30 min. The reaction was terminated by adding 0.1 N Na2CO3 [44]. Absorbance was scaled at 405 nm using a Biosystm 310 plus spectrophotometer. The IC50 values were evaluated using a regression equation derived from graphing concentrations ranging from 1.95 to 1,000 μg·mL−1 against the corresponding % of inhibition.

α-glucosidase ( % ) = ( OD control − OD blank ) / OD blank × 100 .

2.9 Antimicrobial evaluation

The EPS was tested as an antimicrobial compound by agar well diffusion approach against the following bacterial ATCC spectrum, G +ve Bacillus subtilis (ATCC 6633), Staph. aureus (ATCC 6538), and Enterococcus faecalis (ATCC 10541). G −ve bacteria were E. coli (ATCC 8739), K. pneumoniae (ATCC13883), and Salmonella typhi (ATCC 6539). An inoculum suspension was adjusted for the broth dilution standard protocol, and inoculated agar plates were within 15 min. All dried agar was streaked in three directions. After drying the agar for 15 min, a hole with a 6–8 mm diameter is punched aseptically with a sterile cork borer or a tip. EPSF8 and gentamicin were the reference drugs dissolved in MDSO at 10 mg·mL−1. Then, 100 ml of EPSF8 was added to the well at the required concentration. Within 15 min of disposal, plates were incubated for 16–48 h, and the inhibition zone widths (in mm) around the wells were measured to the nearest full millimeter at the moment of significant growth reduction [45]. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were investigated following the Clinical and Laboratory Standards Institute (CLSI) [46].

2.10 Antibiofilm assessment

We assessed how EPS affected the production of biofilms in 96-well polystyrene flat-bottom plates. In summary, 300 μL of trypticase soy yeast broth with a final concentration of 106 CFU·mL−1 was cultivated in sublethal doses of 75, 50, and 25% of MBC. After 48 h of incubation at 37°C, the biofilm grown on the plates was dyed for 15 min at 37℃ using a 0.1% crystal violet aqueous solution. The excess stain was removed from the plate with sterile dH2O after incubation. Each well received 250 μL of 95% C2H5OH to solubilize the dye attached to the cells. A microplate reader was used to measure the absorbance at 570 nm after 15 min [47]:

Biofilm inhibition ( % ) = [ 1 − ( Ab sample − Ab blank ) / ( Ab control − Ab blank ] × 100 .

2.11 Statistical analysis

The data were analyzed using one-way ANOVA and Duncan’s test for multiple concentration comparisons. Normal distribution was confirmed with Kolmogorov–Smirnov and Shapiro–Wilk tests. Statistical analyses were performed using SPSS v25 with a significance level of P ≤ 0.05 and a sample size of n = 3 in triplicates.

3 Results

3.1 Isolation and phylogenetic analysis of the EPS-producing bacterial isolate

Ten bacterial isolates were collected from the Red Sea and subjected to screening for EPS synthesis. This screening process involved evaluating their cultural properties and morphological characteristics and measuring the yield of EPS production. The marine bacterium (F8) strain was found to be the highest EPS producer (6.98 g·L−1), with a main fraction of 82.4%. The selected strain was studied microbiologically, and it was a G −ve, non-capsulated, and non-spore-forming bacterium (Table S1). In addition, the strain was studied biochemically and physiologically. It was positive for the following tests (catalase, citrate, oxidase, nitrate reduction, and mannitol) and negative for the rest of the tests (Table S2).

Molecular 16S rRNA sequencing was then carried out, and the phylogenetic tree involved a comparative analysis of sequences that exhibited a significant level of resemblance between the rRNA sequences of the chosen bacterium under investigation. The obtained rRNA gene sequences were observed to correspond to Pseudomonas sp. strain AHG22 (Figure 1), indicating that the tree was generated correctly. Confirmation of the identification of Pseudomonas sp. strain AHG22 was established using the accession number (OQ931874). The BLAST tool was employed to analyze the provided DNA sequence, which was subsequently submitted to the NCBI GenBank database.

Figure 1 Phylogenetic tree analysis of Pseudomonas sp. strain AHG22 based on 16S rRNA gene sequencing.
Figure 1

Phylogenetic tree analysis of Pseudomonas sp. strain AHG22 based on 16S rRNA gene sequencing.

3.2 Production, partial purification, and chemical composition analysis of EPSF8

The F8 bacterial strain synthesized EPS (EPSF8) with a yield of 6.98 g·L−1. Subsequently, EPSF8 was subjected to UV absorption spectra in the range of 200–800 nm (Figure S1) and had no protein when tested by FT-IR spectroscopy, where the broad characteristic peak at 3588.17 cm−1 was assigned to OH−1 stretching vibration. The band at 2933.66 cm−1 was correlated with the stretching vibration of C–H in the sugar ring. Also, the absorption at 1619.88 cm−1 referred to COO− vibration and 1292.29 cm−1 to the symmetrical COO− stretching vibration, which proved the presence of uronic acid. The band at 1081.53 cm−1 indicated the SO3 group and was characteristic absorption at 853.94 cm−1 arising from β-configuration of the sugar units (Figure 2).

Figure 2 FTIR spectra of EPSF8 displaying the main functional groups.
Figure 2

FTIR spectra of EPSF8 displaying the main functional groups.

The HPLC chromatogram of EPSF8 revealed the monosaccharides fractions (glucose:galacturonic acid: xylose:rhamnose) with a molar ratio of 1:2:2:3, respectively (Figure 3).

Figure 3 HPLC chromatogram of the EPSF8 from Pseudomonas sp. strain AHG22.
Figure 3

HPLC chromatogram of the EPSF8 from Pseudomonas sp. strain AHG22.

3.3 Antioxidant evaluation of EPSF8

The efficacy of EPSF8 in scavenging DPPH radicals was evaluated at 1.95–1,000 μg·mL−1 doses. The DPPH scavenging percentage is enhanced by increasing EPSF8 concentrations from 62.5 to 1,000 µg·mL−1. At its lowest tested concentration of 1.95 μg·mL−1, EPSF8 scavenged 14.8% of DPPH radicals, increased progressively with higher concentrations, reaching 22.7% at 3.9 μg·mL−1, 30.7% at 7.8 μg·mL−1, 37.2% at 15.6 μg·mL−1, and 45.3% at 31.2 μg·mL−1. The scavenging peaked at 84.2% at the highest tested concentration of 1,000 μg·mL−1. The IC50 value of EPSF8 against DPPH was calculated as 46.99 µg·mL−1 (Figure 4) compared to ascorbic acid (IC50 = 2.52 µg·mL−1) (Figure S2). For H2O2 assessment, the maximum antioxidant activity was 77.03 ± 1.20% after 1 h at 1,000 µg·mL−1, and the IC50 value was 300 µg·mL−1 after 60 min (Figure 5) compared to control (IC50 = 88.71 ± 0.98 µg·mL−1) (Table S3). Similarly, the maximum activity for ABTS˙+ was found after 60 min to be 67.30 ± 1.12% at 1,000 µg·mL−1, and IC50 was 300 µg·mL−1 after 1 h (Figure 6) compared to ascorbic acid (IC50 = 87.50 ± 0.75 µg·mL−1) as control (Table S3). For NO antioxidant assessment, the maximum activity (74.34 ± 1.08%) was recorded after 1 h at 1,000 µg·mL−1, and the IC50 was detected at 100 µg·mL−1 after 60 min (Figure 7) compared to the control (IC50 = 20.81 µg·mL−1) (Table S4). The TAC of EPSF8 showed a TAC of 219.45 μg·mg−1 AAE. At the same time, the FRAP assay also determined the antioxidant capacity of EPSF8 to be 54.15 μg·mg−1 AAE. All data are presented as mean ± SD (n = 3, P < 0.05).

Figure 4 DPPH radical scavenging by EPSF8 (1.95–1000 µg/ml) increased dose-dependently. Data are shown as mean ± SD. One-way ANOVA was utilized for data analysis (n = 3, P< 0.05).
Figure 4

DPPH radical scavenging by EPSF8 (1.95–1000 µg/ml) increased dose-dependently. Data are shown as mean ± SD. One-way ANOVA was utilized for data analysis (n = 3, P< 0.05).

Figure 5 Dose- and time-dependent H2O2 scavenging activity of EPSF8. Results expressed as mean ± SD (n = 3, p < 0.05).
Figure 5

Dose- and time-dependent H2O2 scavenging activity of EPSF8. Results expressed as mean ± SD (n = 3, p < 0.05).

Figure 6 Concentration-dependent ABTS•+ radicals’ cation scavenging activity of EPSF8 (100–1000 μg/ml). Values represent mean ± SD (n = 3).
Figure 6

Concentration-dependent ABTS•+ radicals’ cation scavenging activity of EPSF8 (100–1000 μg/ml). Values represent mean ± SD (n = 3).

Figure 7 Nitric oxide (NO) radical scavenging activity of EPSF8 (100-1000 μg/ml) and time intervals (15-60 min). Data are presented as mean ± SD (n = 3).
Figure 7

Nitric oxide (NO) radical scavenging activity of EPSF8 (100-1000 μg/ml) and time intervals (15-60 min). Data are presented as mean ± SD (n = 3).

3.4 Anti-inflammatory assessment of EPSF8

The ability of EPSF8 to reduce inflammation was estimated by investigating its in vitro inhibition effects against both COX-2 and 5-LOX. At the lowest concentration of 0.98 μg·mL−1, EPSF8 inhibited LOX by 11.45%. The inhibition increased progressively with higher concentrations, reaching 17.93% at 1.95 μg·mL−1, 29.30% at 3.9 μg·mL−1, 46.02% at 7.81 μg·mL−1, and 54.16% at 15.63 μg·mL−1. Potent LOX inhibition started at 31.25 μg·mL−1, where 65.87% inhibition was observed. EPSF8 displayed its maximum LOX inhibitory activity of 79.54% at the highest tested concentration of 125 μg·mL−1 (Figure 8). The IC50 value for EPSF8 on 5-LOX was 14.82 compared to that of ibuprofen (1.5 ± 1.3 µg·mL−1; Table S5).

Figure 8 EPSF8 dose-dependently inhibits 5-LOX and COX-2. EPSF8 concentrations increased inflammatory enzyme inhibition. Data is shown as mean ± SD (n = 3). Significant differences between means were determined at p < 0.05 using one-way ANOVA.
Figure 8

EPSF8 dose-dependently inhibits 5-LOX and COX-2. EPSF8 concentrations increased inflammatory enzyme inhibition. Data is shown as mean ± SD (n = 3). Significant differences between means were determined at p < 0.05 using one-way ANOVA.

For in vitro inhibition of COX-2, at 0.98 μg·mL−1, EPSF8 inhibited COX-2 by 12.73%. The inhibition increased progressively with higher concentrations, reaching 21.94% at 1.95 μg·mL−1, 30.52% at 3.9 μg·mL−1, 43.74% at 7.81 μg·mL−1, and 52.98% at 15.63 μg·mL−1. Potent COX-2 inhibition started at 31.25 μg·mL−1, where 61.90% inhibition was observed. EPSF8 displayed its maximum COX-2 inhibitory activity of 86.33% at the highest tested concentration of 125 μg·mL−1 (Figure 8). The IC50 value of EPSF was 15.49 µg·mL−1 compared to that of celecoxib (0.28 ± 1.7 µg·mL−1; Table S6). A positive correlation between the increasing concentration of EPSF8 and the extent of inhibition was observed in both enzymatic activities.

3.5 BChE inhibition by EPSF8

Different concentrations (0.195–100 μg·mL−1) of EPSF8 were tested against BChE, and the results were compared to rivastigmine, a control drug. Minimal inhibition of 0.2% was observed at the lowest tested concentration of 0.195 μg·mL−1. The inhibition increased progressively as the concentration of EPSF8 increased, with 12.2% inhibition starting to be observed at 1.56 μg·mL−1. EPSF8 exhibited its maximal inhibitory activity of 83% against BChE at the highest tested concentration of 100 μg·mL−1. In between the lowest and highest concentrations, the inhibition ranged from 1.3% at 0.39 μg·mL−1 up to 73.3% at 50 μg·mL−1, showing a steady dose-dependent increase in BChE inhibition by EPSF8. IC50 values for EPSF8 and rivastigmine were 11.36 and 2.91 μg·mL−1, respectively (Figure 9 and Figure S5).

Figure 9 In vitro inhibition of BChE by EPSF8 at increasing concentrations. Results are presented as mean ± SD (n = 3). One-way ANOVA determined statistical significance (p < 0.05) between means.
Figure 9

In vitro inhibition of BChE by EPSF8 at increasing concentrations. Results are presented as mean ± SD (n = 3). One-way ANOVA determined statistical significance (p < 0.05) between means.

3.6 Anti-obesity assessment of EPSF8

The inhibitory effect of EPSF8 against lipase at different concentrations (1.95–1,000 μg·mL−1) was compared with orlistat at the same concentrations. It was observed that the enzyme inhibition increased as the EPSF8 concentration increased. A minimal lipase inhibition of 3.7% was observed at the lowest tested concentration of 1.95 μg·mL−1. The inhibition increased progressively as the concentration increased, reaching 14.8% at 3.9 μg·mL−1, 25% at 7.81 μg·mL−1, 36.3% at 15.62 μg·mL−1, and 37.7% at 31.25 μg·mL−1. Potent lipase inhibition started around 62.5 μg·mL−1, where 48.2% inhibition was attained. At the highest tested concentration of 1,000 μg·mL−1, EPSF8 exhibited its maximal lipase inhibitory activity of 92.6%. The IC50 values for EPSF8 and orlistat were calculated to be 56.12 and 20.08 μg·mL−1, respectively (Figure 10 and Figure S6).

Figure 10 In vitro dose-dependent inhibition of pancreatic lipase by EPSF8. Mean ± SD (n = 3). Differences were significant at p < 0.05 by one-way ANOVA.
Figure 10

In vitro dose-dependent inhibition of pancreatic lipase by EPSF8. Mean ± SD (n = 3). Differences were significant at p < 0.05 by one-way ANOVA.

3.7 Antidiabetic activity of EPSF8

The DNSA method was carried out to investigate whether EPSF8 could act as a natural antidiabetic drug, and the inhibition assay was carried out against α-amylase and α-glucosidase enzymes. EPSF8 was tested at different concentrations for both enzymes (1.95–1,000 µg·mL−1), and the same range was used for acarbose, which served as the control used in this experiment. At 1.95 μg·mL−1, EPSF8 inhibited amylase by 11.2%. The inhibition increased to 17.8% at 3.91 μg·mL−1, 24.7% at 7.81 μg·mL−1, and 31.4% at 15.62 μg·mL−1, indicating a steady dose-dependent increase in amylase inhibition by EPSF8. The second maximum inhibition of 67.7% was observed at 500 μg·mL−1, and the highest concentration tested at 1,000 μg·mL−1 EPSF8, showed the highest inhibition activity of 75% (Figure 11). The IC50 of EPSF8 was 93.1 μg·mL−1 for in vitro α-amylase, and that of acarbose was 50.93 (Figure S7).

Figure 11 Dose-dependent inhibition of α-amylase by EPSF8. Elevated EPSF8 concentrations correlated with higher α-amylase inhibition. Results are shown as mean ± SD (n = 3). One-way ANOVA was used to determine statistical significance at p < 0.05 for mean differences.
Figure 11

Dose-dependent inhibition of α-amylase by EPSF8. Elevated EPSF8 concentrations correlated with higher α-amylase inhibition. Results are shown as mean ± SD (n = 3). One-way ANOVA was used to determine statistical significance at p < 0.05 for mean differences.

On the other hand, EPSF8 exhibited concentration-dependent inhibitory activity against the α-glucosidase enzyme. At the lowest concentration of 1.95 μg·mL−1, EPSF8 inhibited α-glucosidase by 10.2%. The inhibition increased progressively with higher concentrations, reaching 16.7% at 3.91 μg·mL−1, 22.4% at 7.81 μg·mL−1, 30% at 15.63 μg·mL−1, and 35.9% at 31.25 μg·mL−1. Potent α-glucosidase inhibition started at 62.5 μg·mL−1, where 42.2% inhibition was observed. EPSF8 showed its maximum α-glucosidase inhibitory activity of 71% at the highest tested concentration of 1,000 μg·mL−1 (Figure 12). Its IC50 was 127.28 and 4.13 μg·mL−1 for acarbose (Figure S8) (Table S7).

Figure 12 Concentration-dependent α-glucosidase inhibition by EPSF8 with concentrations from 1.95 to 1000 μg/mL (n = 3, p < 0.05, one-way ANOVA).
Figure 12

Concentration-dependent α-glucosidase inhibition by EPSF8 with concentrations from 1.95 to 1000 μg/mL (n = 3, p < 0.05, one-way ANOVA).

3.8 Antimicrobial and antibiofilm assessment of EPSF8

EPSF8 was supplemented on the Mueller–Hinton agar plate. After incubation, inhibition zones were represented as mm. The tested organisms were G +ve B. subtilis (ATCC 6633) Staph. aureus (ATCC 6538) and E. faecalis (ATCC 29212). G −ve bacteria were E. coli (ATCC 8739), K. pneumoniae (ATCC13883), and S. typhi (ATCC 6539). For the G +ve spectrum, against B. subtilis, EPSF8 produced an inhibition zone of 30 ± 0.5 mm, larger than the 23 ± 0.2 mm zone caused by gentamicin. For S. aureus, EPSF8 and gentamicin both generated an equal inhibition zone of 27 ± 0.3 mm. However, EPSF8 showed superior inhibition of E. faecalis, creating a 46 ± 0.3 mm zone compared to just 30 ± 0.4 mm for gentamicin (Figures 13 and 14). MICs, MBCs, and MBC/MIC ratios were then investigated. Against B. subtilis, EPSF8 exhibited the lowest MIC of 15.62 μg·mL−1 and a corresponding MBC of 31.25 μg·mL−1, resulting in an MBC/MIC ratio of 2. For S. aureus, the MIC and MBC were the same at 15.62 and 31.25 μg·mL−1, respectively, also giving an MBC/MIC ratio of 2, while EPSF8 displayed the highest potency against E. faecalis with the lowest MIC of 7.8 μg·mL−1 and matched by an MBC of 7.8 μg·mL−1, resulting in an MBC/MIC ratio of 1 indicating bactericidal effects (Table 1).

Figure 13 Inhibition zones (mm) of EPSF8 towards G+ve and G-ve ATCC bacteria.
Figure 13

Inhibition zones (mm) of EPSF8 towards G+ve and G-ve ATCC bacteria.

Figure 14 Antibacterial effect of EPSF8 against 3 ATCC G+ve pathogenic bacteria (a) B. subtilis, (b) S. aureus, and (c) E. faecalis.
Figure 14

Antibacterial effect of EPSF8 against 3 ATCC G+ve pathogenic bacteria (a) B. subtilis, (b) S. aureus, and (c) E. faecalis.

Table 1

Inhibition zones (in mm), MIC, MBC, and MBC/MIC ratio of EPSF8 against 6ATCC bacteria

Pathogenic microorganisms EPSF8 (mm) Gentamicin (control) MIC (µg·mL−1) MBC (µg·mL−1) MBC/MIC ratio
B. subtilis (ATCC 6633) 30 ± 0.5 23 ± 0.2 15.62 31.25 2
Staph. aureus (ATCC 6538) 27 ± 0.3 27 ± 0.3 15.62 31.25 2
E. faecalis (ATCC 29212) 46 ± 0.3 30 ± 0.4 7.8 7.8 1
E. coli (ATCC 8739) 22 ± 0.2 16 ± 0.2 125 125 1
K. pneumoniae (ATCC13883) 19 ± 0.1 17 ± 0.2 125 250 2
S. typhi (ATCC 6539) 26 ± 0.2 24 ± 0.3 62.5 125 2

For the G −ve spectrum, for E. coli, EPSF8 produced an inhibition zone of 22 ± 0.2 mm, while gentamicin generated a smaller 16 ± 0.2 mm zone. For K. pneumoniae, inhibition zones were comparable at 19 ± 0.1 mm for EPSF8 and 17 ± 0.2 mm for gentamicin. EPSF8 exhibited the strongest inhibition of S. typhi, creating a 26 ± 0.2 mm zone compared to 24 ± 0.3 mm for gentamicin (Figures 13 and 15). Following MICs, MBCs, and MBC/MIC ratios were examined; against E. coli, EPSF8 displayed the highest MIC of 125 μg·mL−1 and a matching MBC of 125 μg·mL−1, resulting in an MBC/MIC ratio of 1. For K. pneumoniae, the MIC was the same at 125 μg·mL−1, but the MBC was slightly higher at 250 μg·mL−1, giving an MBC/MIC ratio of 2. EPSF8 exhibited the greatest potency against S. typhi with the lowest MIC of 62.5 μg·mL−1 and a MBC of 125 μg·mL−1, resulting in an MBC/MIC ratio of 2 (Table 1).

Figure 15 Antibacterial effect of EPSF8 against 3 ATCC G-ve pathogenic bacteria. (a) E. coli, (b) K. pneumoniae, and (c) S. typhi.
Figure 15

Antibacterial effect of EPSF8 against 3 ATCC G-ve pathogenic bacteria. (a) E. coli, (b) K. pneumoniae, and (c) S. typhi.

For the same bacterial spectrum except for E. coli, EPSF8 was tested as antibiofilm based on the previously addressed MIC and MBC values (Figure 16). For G +ve bacteria, EPSF8 showed the lowest antibiofilm activity, 91.89% for Staph. aureus at 75% of MBC. Conversely, the highest antibiofilm activity was 93.47% for E. faecalis. On the other hand, for G −ve bacteria, EPSF8 exhibited the lowest activity (87.91%) for K. pneumoniae and the highest (91.79%) for S. typhi.

Figure 16 Antibiofilm activity of EPSF8 against ATCC bacteria at different %MBC.
Figure 16

Antibiofilm activity of EPSF8 against ATCC bacteria at different %MBC.

4 Discussion

Microbial EPSs exhibit a remarkable range of diversity. Multifunctional carbohydrates evidenced a diverse range of physiological responses, thereby showcasing their noteworthy potential in augmenting public health. Currently, a substantial portion of marketable EPSs can be attributed to the derivation of microorganisms. One primary advantage of EPSs lies in their inherent capacity for modulating chemical composition and structure. This characteristic renders them particularly well-suited for targeted applications within pharmaceuticals and medicine.

Henceforth, the main goal of this study was to identify microbial EPSs possessing chemically suitable architectures, which has been pursued via comprehensive screening investigations conducted within untapped marine ecosystems.

A marine bacterium Pseudomonas sp. strain AHG22 was isolated and identified (Figure 1), which produced EPS with a yield of 6.98 g·L−1 with a core fraction (82.4%), and coded EPSF8. The EPSF8 was then subjected to FT-IR and revealed uronic acid (14.70%), sulfate (25.65%), and N-acetyl glucosamine (8.55%) (Figure 2). HPLC chemical investigation revealed monosaccharide fractions (glucose:galacturonic acid:xylose:rhamnose) with molar ratios 1:2:2:3, respectively (Figure 3).

At different concentrations, the antioxidant activity of EPSF8 was investigated by DPPH, H2O2, ABTS˙+, NO, TAC, and FRAP assay. For DPPH radical scavenging activity, IC50 values of EPSF8 and the standard compound ascorbic acid were determined to be 46.99 and 2.52 μg·mL−1, respectively (Figure S2). The EPSF8 extract displayed the highest antioxidant at a concentration of 1,000 μg·mL−1; EPSF8 exhibited 77.03 ± 1.20 μg·mL−1 of antioxidant activity in the H2O2 assay after 60 min (Figure 5). EPSF8 also showed 67.30 ± 1.12 μg·mL−1 of antioxidant activity in the ABTS˙+ assay after 60 min (Figure 6). In addition, for NO assay, EPSF8 yielded maximum activity (74.34 ± 1.08 μg·mL−1) after 1 h at a 1,000 μg·mL−1 concentration (Figure 7). All the antioxidant activities measured in the H2O2, ABTS˙+, and NO assays positively correlated with the tested concentration values. For the TAC assay, EPSF8 had 219.45 µg·mg−1 equivalent AAE and 54.15 µg·mg−1 AAE for FRAP testing.

The antioxidant efficiency of microbial EPS has been explored primarily by in vitro assays [6,7,8,9]. Multiple factors, such as monosaccharide molar ratio, molecular weight, or functional groups, may potentially influence the EPS’s antioxidant activity. In addition, the techniques employed for extraction and purification may also have an impact. The low molecular weight EPSs that are acidic polymers, as in the case of the current EPSF8, frequently displayed greater antioxidant capabilities than the neutral ones [48].

Therefore, EPSF8 could be regarded as a potentially green alternative agent against synthetic antioxidants due to its involvement in mitigating oxidative stress by scavenging different free radicals, inhibiting lipid peroxidation, and reducing the activity of metal ions. However, to confirm these data, the activity of EPSF8 should be supported by in vivo tests.

The enzymes 5-LOX and COX-2 are key targets in developing anti-inflammatory drugs. This is because they play a vital role in regulating the production of leukotrienes and prostaglandins – important inflammatory mediators. By attenuating the activity of these enzymes, it is possible to mitigate the inflammatory response and potentially alleviate associated symptoms [49]. We explored the anti-inflammatory potency of EPSF8 by evaluating it against 5-LOX and COX-2 enzymes.

Our current findings revealed that EPSF8 had an IC50 of 14.82 μg·mL−1 for inhibiting 5-LOX activity (Figure 8), compared to an IC50 of 1.5 ± 1.3 μg·mL−1 for ibuprofen (Table S5). EPSF8 also had an IC50 of 15.49 μg·mL−1 for inhibiting COX-2 activity (Figure 8), compared to an IC50 of 0.28 ± 1.7 μg·mL−1 for celecoxib. As observed, increasing the concentration of EPSF8 resulted in a dose-dependent elevation in inhibiting 5-LOX and COX-2 activities. The prevailing notion posits that the primary impact of EPS lies in its ability to regulate cytokines and their subsequent transcription factors [50]. The pro-inflammatory cytokines TNF-α, IL-1, and IL-6, along with the anti-inflammatory cytokine IL-10, have been identified as the key mediators responsible for the effects exerted by these natural products [51].

BChE is an enzyme categorized as nonspecific cholinesterase that catalyzes the hydrolysis of choline-based esters. By hydrolyzing acetylcholine (ACh), BChE plays a crucial part in preserving appropriate cholinergic function, similar to acetylcholinesterase (AChE) [52]. The implementation of targeted inhibition of BChE has been widely acknowledged as a promising therapeutic strategy in the context of Alzheimer’s disease [53]. Therefore, in pursuit of further elucidation to explore some bacterial in vitro anti-BChE activity, EPSF8 was tested for anti-BChE activity at concentrations ranging from 0 to 100 μg·mL−1. EPSF8 had an IC50 of 11.36 μg·mL−1 against BChE (Figure 9), compared to an IC50 of 2.91 μg·mL−1 for the rivastigmine control (Figure S5). Recent scientific investigations have revealed the neuroprotective properties of secondary metabolites derived from marine bacteria. For example, EPSF6, EPS with Mw of 2.7 × 104 g·mol−1 sourced from Bacillus Velezensis AG6 had an anti-AChE activity with IC50 (100–1,000 μg·mL−1) = 439.05 μg·mL−1 compared to that of the eserine control (0.02–0.12 μg·mL−1) = 0.09 μg·mL−1 [9]. From the same source, EPSR5, an acidic EPS with an Mw of 4.9 × 104 g·mol−1 extracted from Kocuria sp., revealed the anti-AChE activity with IC50 = 797.02 μg·mL−1 compared to that of eserine’s of 0.09 μg·mL−1 [8]. Also, pyrroles and other AChE inhibitors were generated by Streptomyces lateritius [54]. In addition, Gangalla et al. have documented the potential therapeutic impact of a polysaccharide sourced from Bacillus amyloliquefaciens RK3 in mice. This finding holds promise for treating various disorders driven by ACh insufficiency [55].

Empirical investigations have demonstrated that the inhibitory impact of COX-2 diminishes the inflammatory cascade, thereby exerting a noteworthy influence on the neurodegenerative processes associated with the progression of Alzheimer’s disease [56]. In light of its current attributes, EPSF8 exhibited selective anti-cyclooxygenase properties, inhibited BChE, and possessed antioxidant capabilities. These characteristics position EPSF8 as a potentially advantageous acidic microbial polysaccharide for controlling and restricting Alzheimer’s disease.

To assess the anti-obesity potential of EPSF8 through lipase enzyme inhibition, EPSF8 was tested at concentrations ranging from 1.95 to 1,000 μg·mL−1 compared to similar concentrations of the Orlistat control. The IC50 of EPSF8 for lipase inhibition was 56.12 μg·mL−1 (Figure 10) compared to 20.08 μg·mL−1 for orlistat (Figure S6). Microbial EPS’s hypoglycemic and cholesterol-lowering efficiency has been confirmed mainly through in vitro experiments [57,58]. Although the precise mechanisms underlying the EPS’s ability to decrease cholesterol are still unclear, it has been speculated that they do so by acting like dietary fibers and promoting the synthesis of bile acids [59]. Additionally, the hypoglycemic action of such EPS has been linked to the inhibition of α-glucosidase or α-amylase [60].

Decreasing postprandial hyperglycemia is the main priority for diabetes treatment. Academics have acknowledged that restricting glucosidase with inhibitors efficiently controls carbohydrate absorption and reduces the risk of postprandial hyperglycemia [61]. These inhibitors can potentially induce the liberation of glucagon-like peptide 1 (GLP-1) and subsequently elicit a decline in glycated hemoglobin [62]. EPSF8 extracted from Pseudomonas sp. strain AHG22 exhibited inhibitory potential against α-amylase and α-glucosidase. The results showed that EPSF8 had an IC50 of 93.1 μg·mL−1 for amylase inhibition (Figure 11), compared to that of 50.93 μg·mL−1 for the acarbose control (Figure S7). For α-glucosidase inhibition, EPSF8 had an IC50 of 127.28 μg·mL−1 (Figure 12) compared to that of 4.13 μg·mL−1 for the acarbose control (Figure S8). In line with our results, 11 Annona muricata endophytic bacterial strains inhibited α-amylase activity. With 72.22% inhibition, DS21, a G −ve bacterium, was the most active [63]. Bacteria’s multifactorial inhibition of glucosidases remains undisclosed. It might be competitive or non-competitive inhibition, inhibitors bind to glucosidases’ active sites, blocking substrate binding, non-competitive; the organism’s metabolite binds to allosteric sites on glucosidases, modifying their conformation and blocking carbohydrate breakdown or substrate binding; bacteria-derived inhibitors bind to substrate, prevents where the substrate is bound. The mechanisms by which bacteria suppress different glucosidases may vary and require further in vitro and in vivo research [20].

Finally, EPSF8 was evaluated as a natural antimicrobial substitute and an alternative antibiofilm agent to antibiotics by agar well diffusion assay. A hole with a 6–8 mm diameter was punched aseptically with a sterile cork borer, and a volume (20–100 µL) of EPSF8 was supplemented on a Mueller–Hinton agar plate. After incubation, inhibition zones were represented as mm. The tested organisms were G +ve B. subtilis (ATCC 6633) Staph. aureus (ATCC 6538), and E. faecalis (ATCC 29212). G −ve bacteria were E. coli (ATCC 8739), K. pneumoniae (ATCC13883), and S. typhi (ATCC 6539). For the G +ve spectrum, the highest inhibition zone was found to be 46 ± 0.3 mm for E. faecalis (ATCC 29212), compared to that of 30 ± 0.4 mm for gentamicin. For the G −ve spectrum, the highest inhibition zone was 26 ± 0.2 mm for S. typhi (ATCC 6539) compared to that of 24 ± 0.3 mm gentamicin. EPSF8 exhibited antibacterial activity toward G +ve and G −ve ATCC bacteria (Figures 13–15).

In the MBC test, EPSF8 showed the lowest MBC of 7.8 μg·mL−1 against the G +ve bacterium E. faecalis (ATCC 29212). It had an MBC of 125 μg·mL−1 against the G −ve bacteria K. pneumoniae (ATCC 13883) and S. typhi (ATCC 6539) (Table 1). The MBC/MIC ratio indicated antibacterial activity. A ratio of MBC/MIC ≤4 indicates bactericidal impact, while a ratio >4 indicates bacteriostatic effect [64,65]. Based on the previous findings, we may conclude that EPSF8 has a bactericidal activity against both bacterial spectrums, especially for the G +ve bacterium E. faecalis (ATCC 29212) and against E. coli (ATCC 8739).

Next, the MTP plate assay was performed as an antibiofilm assay for the same bacterial spectrum (Figure 16), except for E. coli. Previous MICs and MBCs were used to test EPSF8 as an anti-biofilm. EPSF8 had the lowest antibiofilm activity (91.89%) for Staph. aureus at 75% MBC and the highest (93.47%) for E. faecalis. Concerning G −ve bacteria, EPSF8 had the lowest antibiofilm activity for K. pneumoniae (87.91%) and the highest for S. typhi (91.79 %) at 75% MBC.

In alignment with our research findings, an acidic EPSR3 extracted from Bacillus cereus from the Red Sea had an average molecular weight of 1.66 × 104 g·mol−1. It was found to have a strong inhibitory effect on S. aureus (MRSA). The study showed that a 5% concentration of EPSR3 for 60 min was enough to inhibit the growth of MRSA [7]. In contrast to our results, EPSF6 with a molecular weight of 2.7 × 104 g·mol−1 extracted from B. velezensis from the same source was examined for antimicrobial by MTP test against two pathogenic ATCC G +ve, two G −ve bacteria. However, neither significant activity was reported [9]. Microbial EPS acts against animal and plant bacteria alike. Drira et al. reported that EPS synthesized by Porphyridium sordidum could control fungal growth in plants. EPS may serve as a stimulant to elevate the resilience of A. thaliana to F. oxysporum. [66].

EPSs exert antagonistic activity against pathogenic bacteria; for instance, in the context of in vitro experimentation; EPS synthesized by Lactobacillus rhamnosus, which was obtained from human breast milk, exhibited noteworthy antibacterial properties against the pathogenic bacteria Salmonella enterica serovar Typhimurium and E. coli [67]. The antimicrobial activity of EPS has also been found to correlate strongly with their physicochemical properties [68]. For example, negatively charged EPS derived from the Lactococcus lactis F-mou strain exhibited a more pronounced inhibitory effect on G +ve pathogens than G −ve ones. Notably, the strain B. cereus ATCC 10702 displayed the highest level of inhibition, indicating its susceptibility to the inhibitory action of the EPS [69]. As mentioned earlier, the findings postulated that the electrostatically charged EPS, specifically the sulfate groups, may facilitate enhanced interactions with G +ve bacteria. This can be attributed to the relatively higher positive charge exhibited by the cell walls of these bacteria.

Similarly, EPSF8 is a negatively charged hetero-EPS due to sulfate and uronic acid side chains, as clarified by FT-IR (Figure 2). Another disruptive impact of EPS is on the bacterial cell envelope, particularly the peptidoglycan layer, rendering it a plausible inhibitory mechanism [70]. This proposition was substantiated by the observation that EPSs such as kefiran exhibited interactions with bacterial or eukaryotic cells. Consequently, it was hypothesized that kefiran functioned as a masking or decoy agent, thereby exerting its inhibitory effects [71].

Therefore, it is likely that this particular action could impede the functionality of the receptors or channels located on the external membrane of the G −ve bacteria. While Zhou et al. suggested another mode of action, the presence of functional groups within the structure of EPS facilitates their interaction with bacterial cell envelopes, ultimately leading to antimicrobial activity [68], as in our explored EPSF8 (uronic acid = 14.70%, sulfate = 25.65% and N-acetyl glucosamine = 8.55%).

It is imperative to emphasize the limitations of embracing microbial EPS in industrial applications, particularly in the context of production and recovery processes. The elevated production costs primarily stem from utilizing costly and specialized nutrients in fermentation media formulation. This factor typically accounts for approximately 30% of the overall expenditure associated with the fermentation process. To optimize cost efficiency, it is advisable to employ more economical substrates, such as cane molasses, sugarcane bagasse, corn steep liquor, etc., for large-scale production purposes [72].

Furthermore, the extraction methods for EPS can be appropriately adjusted to be economically viable and efficient. This modification would result in a substantial reduction in the overall expenses associated with subsequent processes. Finally, to attain elevated EPS yields, it is plausible to boost marine bacterial strains through genetic engineering techniques, such as mutagenic strains and gene manipulations [73]. Additionally, the production of EPS with distinct properties and structures can be accomplished by applying the same approaches [74].

5 Conclusions

EPSF8 is a hetero-acidic EPS sulfated and contains uronic acid and N-acetylglucosamine extracted from Pseudomonas sp. strain AHG22 isolated from the Red Sea, which could be considered as a green substitute for synthetic antioxidants aligning with its selective anti-cyclooxygenase properties. EPSF8 exhibited non-significant antidiabetic, less potent anti-inflammatory effects, and moderate hypocholesterolemic activity. However, it has proved to be considered a broad-spectrum, natural bactericidal, and antibiofilm compound of marine available origin, a potent substitute to traditional antibiotics. It is highly recommended that such findings be validated in different in vivo models and that their chemical structure and molecular formula be investigated. The findings above shed light on the prospective viability of Pseudomonas sp. strain AHG22 and its potential incorporation into the pharmaceutical industry.

Acknowledgments

The authors acknowledge the support via funding from Prince Sattam bin Abdulaziz University, Alkharj, Saudi Arabia, project number (PSAU/2024/R/1445).

  1. Funding information: This study was supported via funding from Prince Sattam bin Abdulaziz University, Alkharj, Saudi Arabia, project number (PSAU/2024/R/1445).

  2. Author contributions: Ghfren S. Aloraini: conceptualization, methodology, investigation, writing – original draft, writing – review and editing; Mona Othman I. Albureikan: methodology, validation, investigation, and writing – review and editing; Aisha M.A. Shahlol: methodology, validation, formal analysis, and writing – review and editing; Taghreed Shamrani: software, formal analysis, data curation, and visualization; Hussam Daghistani: software, formal analysis, data curation, visualization, and writing – review and editing; Mohammad El-Nablaway: methodology, formal analysis, and investigation; Nagwa A. Tharwat: conceptualization, writing – review and editing, validation, writing – original draft, writing, and supervision; Ahmed M. Elazzazy: formal analysis, resources, visualization, data curation, and software; Ahmed F. Basyony: methodology, formal analysis, and writing – review and editing; Ahmed Ghareeb: conceptualization, methodology, investigation, writing – original draft, writing – review and editing and supervision. All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  3. Conflict of interest: The authors state no conflict of interest.

  4. Data availability statement: The data presented in this study are openly available in DDBJ/EMBL/Gen – Bank nucleotide sequence databases at https://www.ncbi.nlm.nih.gov/ (submitted on 06-MAY-2023), reference number GenBank: OQ931874.

References

[1] Barcelos, M. C.S., K. A.C. Vespermann, F. M. Pelissari, and G. Molina. Current status of biotechnological production and applications of microbial exopolysaccharides. Critical Reviews in Food Science and Nutrition, Vol. 60, 2020, pp. 1475–1495.10.1080/10408398.2019.1575791Search in Google Scholar PubMed

[2] Li, W., J. Ji, X. Chen, M. Jiang, X. Rui, and M. Dong. Structural elucidation and antioxidant activities of exopolysaccharides from Lactobacillus helveticus MB2-1. Carbohydrate Polymers, Vol. 102, 2014, pp. 351–359.10.1016/j.carbpol.2013.11.053Search in Google Scholar PubMed

[3] Andrew, M. and G. Jayaraman. Structural features of microbial exopolysaccharides in relation to their antioxidant activity. Carbohydrate Research, Vol. 487, 2020, id. 107881.10.1016/j.carres.2019.107881Search in Google Scholar PubMed

[4] Xu, X., Y. Qiao, Q. Peng, B. Shi, and V. P. Dia. Antioxidant and immunomodulatory properties of partially purified exopolysaccharide from lactobacillus casei isolated from Chinese Northeast. Sauerkraut. Immunological Investigations, Vol. 51, 2022, pp. 748–765.10.1080/08820139.2020.1869777Search in Google Scholar PubMed

[5] Carocho, M., P. Morales, and I. C.F. R. Ferreira. Antioxidants: reviewing the chemistry, food applications, legislation and role as preservatives. Trends in Food Science and Technology, Vol. 71, 2018, pp. 107–120.10.1016/j.tifs.2017.11.008Search in Google Scholar

[6] Abdel-Wahab, B. A., H. F. Abd El-Kareem, A. Alzamami, C. A. Fahmy, B. H. Elesawy, M. Mostafa Mahmoud, et al. Novel exopolysaccharide from marine bacillus subtilis with broad potential biological activities: insights into antioxidant, anti-Inflammatory, cytotoxicity, and anti-alzheimer activity. Metabolites, Vol. 12, 2022, id. 715.10.3390/metabo12080715Search in Google Scholar PubMed PubMed Central

[7] Selim, S., M. S. Almuhayawi, M. T. Alharbi, M. K. Nagshabandi, A. Alanazi, M. Warrad, et al. In vitro assessment of antistaphylococci, antitumor, immunological and structural characterization of acidic bioactive exopolysaccharides from marine Bacillus cereus isolated from Saudi Arabia. Metabolites, Vol. 12, 2022, id. 132.10.3390/metabo12020132Search in Google Scholar PubMed PubMed Central

[8] Alshawwa, S. Z., K. S. Alshallash, A. Ghareeb, A. M. Elazzazy, M. Sharaf, A. Alharthi, et al. Assessment of pharmacological potential of novel exopolysaccharide isolated from marine Kocuria sp. Strain AG5: broad-spectrum biological investigations. Life, Vol. 12, 2022, id. 1387.10.3390/life12091387Search in Google Scholar PubMed PubMed Central

[9] Alharbi, M. A., A. A. Alrehaili, M. O.I. Albureikan, A. F. Gharib, H. Daghistani, M. M. Bakhuraysah, et al. In vitro studies on the pharmacological potential, anti-tumor, antimicrobial, and acetylcholinesterase inhibitory activity of marine-derived Bacillus velezensis AG6 exopolysaccharide. RSC Advances, Vol. 13, 2023, pp. 26406–26417.10.1039/D3RA04009GSearch in Google Scholar

[10] Alharbi, N. K., Z. F. Azeez, H. M. Alhussain, A. M. A. Shahlol, M. O. I. Albureikan, M. G. Elsehrawy, et al. Tapping the biosynthetic potential of marine Bacillus licheniformis LHG166, a prolific sulphated exopolysaccharide producer: structural insights, bio-prospecting its antioxidant, antifungal, antibacterial and anti-biofilm potency as a novel anti-infective lead. Front Microbiol. Vol. 15, 2024, id. 1385493.10.3389/fmicb.2024.1385493Search in Google Scholar PubMed PubMed Central

[11] Chaisuwan, W., Y. Phimolsiripol, T. Chaiyaso, C. Techapun, N. Leksawasdi, K. Jantanasakulwong, et al. The antiviral activity of bacterial, fungal, and algal polysaccharides as bioactive ingredients: potential uses for enhancing immune systems and preventing viruses. Frontiers in Nutrition, Vol. 8, 2021, id. 902.10.3389/fnut.2021.772033Search in Google Scholar PubMed PubMed Central

[12] Wang, Q., M. Wei, J. Zhang, Y. Yue, N. Wu, L. Geng, et al. Structural characteristics and immune-enhancing activity of an extracellular polysaccharide produced by marine Halomonas sp. 2E1. International Journal of Biological Macromolecules, Vol. 183, 2021, pp. 1660–1668.10.1016/j.ijbiomac.2021.05.143Search in Google Scholar PubMed

[13] Chatterjee, S., S. Mukhopadhyay, S. S. Gauri, and S. Dey. Sphingobactan, a new α-mannan exopolysaccharide from Arctic Sphingobacterium sp. IITKGP-BTPF3 capable of biological response modification. International Immunopharmacology, Vol. 60, 2018, pp. 84–95.10.1016/j.intimp.2018.04.039Search in Google Scholar PubMed

[14] Abdalla, A. K., M. M. Ayyash, A. N. Olaimat, T. M. Osaili, A. A. Al-Nabulsi, N. P. Shah, et al. Exopolysaccharides as antimicrobial agents: mechanism and spectrum of activity. Frontiers in Microbiology, Vol. 12, 2021, id. 664395.10.3389/fmicb.2021.664395Search in Google Scholar PubMed PubMed Central

[15] Bello-Morales, R., S. Andreu, V. Ruiz-Carpio, I. Ripa, and J. A. López-Guerrero. Extracellular polymeric substances: still promising antivirals. Viruses, Vol. 14, 2022, id. 1337.10.3390/v14061337Search in Google Scholar PubMed PubMed Central

[16] Rubini, D., P. V. Varthan, S. Jayasankari, B. N. Vedahari, and P. Nithyanand. Suppressing the phenotypic virulence factors of Uropathogenic Escherichia coli using marine polysaccharide. Microbial Pathogenesis, Vol. 141, 2020, id. 103973.10.1016/j.micpath.2020.103973Search in Google Scholar PubMed

[17] Wu, S., G. Liu, W. Jin, P. Xiu, and C. Sun. Antibiofilm and anti-infection of a marine bacterial exopolysaccharide against pseudomonas aeruginosa. Frontiers in Microbiology, Vol. 7, 2016, (accessed January 29, 2023).10.3389/fmicb.2016.00102Search in Google Scholar PubMed PubMed Central

[18] Khodeer, D.M., A. M. Nasr, A. M. Swidan, S. Shabayek, R. M. Khinkar, M. M. Aldurdunji, et al. Characterization, antibacterial, antioxidant, antidiabetic, and anti-inflammatory activities of green synthesized silver nanoparticles using Phragmanthera austroarabica A. G. Mill and J. A. Nyberg extract. Front. Microbiol, Vol. 13, 2023, id. 1078061.10.3389/fmicb.2022.1078061Search in Google Scholar PubMed PubMed Central

[19] Singla, P., A. Bardoloi, and A. A. Parkash. Metabolic effects of obesity: A review. World Journal of Diabetes, Vol. 1, 2010, pp. 76–88.10.4239/wjd.v1.i3.76Search in Google Scholar PubMed PubMed Central

[20] Wang, X., J. Li, J. Shang, J. Bai, K. Wu, J. Liu, et al. Metabolites extracted from microorganisms as potential inhibitors of glycosidases (α-glucosidase and α-amylase): A review. Frontiers in Microbiology, Vol. 13, 2022, id. 1050869.10.3389/fmicb.2022.1050869Search in Google Scholar PubMed PubMed Central

[21] Zeng, Z., S.-Y. Huang, and T. Sun. Pharmacogenomic studies of current antidiabetic agents and potential new drug targets for precision medicine of diabetes. Diabetes Therapy, Vol. 11, 2020, pp. 2521–2538.10.1007/s13300-020-00922-xSearch in Google Scholar PubMed PubMed Central

[22] Hayakawa, M. And H. Nonomura. Humic acid-vitamin agar, a new medium for the selective isolation of soil actinomycetes. Journal of Fermentation Technology, Vol. 65, 1987, pp. 501–509.10.1016/0385-6380(87)90108-7Search in Google Scholar

[23] Krieg, N. R., J. T. Staley, D. R. Brown, B. P. Hedlund, B. J. Paster, N. L. Ward, et al., (Eds.) Bergey’s Manual® of Systematic Bacteriology, Springer, New York, New York, NY, 2010.10.1007/978-0-387-68572-4Search in Google Scholar

[24] Tamura, K., D. Peterson, N. Peterson, G. Stecher, M. Nei, and S. Kumar. MEGA5: Molecular evolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. Molecular Biology and Evolution, Vol. 28, 2011, pp. 2731–2739.10.1093/molbev/msr121Search in Google Scholar PubMed PubMed Central

[25] Liu, C., J. Lu, L. Lu, Y. Liu, F. Wang, and M. Xiao. Isolation, structural characterization and immunological activity of an exopolysaccharide produced by Bacillus licheniformis 8-37-0-1. Bioresource Technology, Vol. 101, 2010, pp. 5528–5533.10.1016/j.biortech.2010.01.151Search in Google Scholar PubMed

[26] Wang, H., X. Jiang, H. Mu, X. Liang, and H. Guan. Structure and protective effect of exopolysaccharide from P. Agglomerans strain KFS-9 against UV radiation. Microbiological Research, Vol. 162, 2007, pp. 124–129.10.1016/j.micres.2006.01.011Search in Google Scholar PubMed

[27] Nicely, W. B. Infrared spectra of carbohydrates. In: Advances in carbohydrate chemistry, M. L. Wolfrom, Tipson, R. S., (Eds.), Academic Press, 1957, pp. 13–33.10.1016/S0096-5332(08)60203-9Search in Google Scholar

[28] Filisetti-Cozzi, T. M. and N. C. Carpita. Measurement of uronic acids without interference from neutral sugars. Analytical Biochemistry, Vol. 197, 1991, pp. 157–162.10.1016/0003-2697(91)90372-ZSearch in Google Scholar

[29] Garrido, M. L. Determination of sulphur in plant material. Analyst, Vol. 89, 1964, pp. 61–66.10.1039/an9648900061Search in Google Scholar

[30] Randall, R. C., G. O. Phillips, P. A. Williams. The role of the proteinaceous component on the emulsifying properties of gum arabic. Food Hydrocolloids, Vol. 2, No. 2, 1988, pp. 131–140.10.1016/S0268-005X(88)80011-0Search in Google Scholar

[31] Brand-Williams, W., M. E. Cuvelier, and C. Berset. Use of a free radical method to evaluate antioxidant activity. LWT – Food Science and Technology, Vol. 28, 1995, pp. 25–30.10.1016/S0023-6438(95)80008-5Search in Google Scholar

[32] Ruch, R. J., K. A. Crist, and J. E. Klaunig. Effects of culture duration on hydrogen peroxide-induced hepatocyte toxicity. Toxicology and Applied Pharmacology, Vol. 100, 1989, pp. 451–464.10.1016/0041-008X(89)90293-7Search in Google Scholar

[33] Miller, N. J. and C. A. Rice-Evans. The relative contributions of ascorbic acid and phenolic antioxidants to the total antioxidant activity of orange and apple fruit juices and blackcurrant drink. Food Chemistry, Vol. 60, 1997, pp. 331–337.10.1016/S0308-8146(96)00339-1Search in Google Scholar

[34] Balakrishnan, N., A. B. Panda, N. R. Raj, A. Shrivastava, and R. Prathani. The evaluation of nitric oxide scavenging activity of acalypha indica linn root. Asian Journal of Research in Chemistry, Vol. 2, 2009, pp. 148–150.Search in Google Scholar

[35] Prieto, P., M. Pineda, and M. Aguilar. Spectrophotometric quantitation of antioxidant capacity through the formation of a phosphomolybdenum complex: specific application to the determination of vitamin E. Analytical Biochemistry, Vol. 269, 1999, pp. 337–341.10.1006/abio.1999.4019Search in Google Scholar PubMed

[36] Lahmass, I., S. Ouahhoud, M. Elmansuri, A. Sabouni, E. Mohammed, R. Benabbas, et al. Determination of antioxidant properties of six by-products of crocus sativus l. (saffron) plant products. Waste and Biomass Valorization, Vol. 9, 2018, pp. 1349–1357.10.1007/s12649-017-9851-ySearch in Google Scholar

[37] Benzie, I. F. and J. J. Strain. The ferric reducing ability of plasma (FRAP) as a measure of “antioxidant power”: the FRAP assay. Analytical Biochemistry, Vol. 239, 1996, pp. 70–76.10.1006/abio.1996.0292Search in Google Scholar PubMed

[38] Athamena, S., S. Laroui, W. Bouzid, and A. Meziti. The antioxidant, anti-inflammatory, analgesic and antipyretic activities of Juniperu thurifera. Journal of Herbs, Spices and Medicinal Plants, Vol. 25, 2019, pp. 271–286.10.1080/10496475.2019.1608886Search in Google Scholar

[39] Granica, S., M. E. Czerwińska, J. P. Piwowarski, M. Ziaja, and A. K. Kiss. Chemical composition, antioxidative and anti-Inflammatory activity of extracts prepared from aerial parts of Oenothera biennis L. And Oenothera paradoxa Hudziok obtained after seeds cultivation. Journal of Agricultural and Food Chemistry, Vol. 61, 2013, pp. 801–810.10.1021/jf304002hSearch in Google Scholar PubMed

[40] Amessis-Ouchemoukh, N., K. Madani, P. L.V. Falé, M. L. Serralheiro, and M. E.M. Araújo. Antioxidant capacity and phenolic contents of some Mediterranean medicinal plants and their potential role in the inhibition of cyclooxygenase-1 and acetylcholinesterase activities. Industrial Crops and Products, Vol. 53, 2014, pp. 6–15.10.1016/j.indcrop.2013.12.008Search in Google Scholar

[41] Gorun, V., I. Proinov, V. Băltescu, G. Balaban, and O. Bârzu. Modified Ellman procedure for assay of cholinesterases in crude enzymatic preparations. Analytical Biochemistry, Vol. 86, 1978, pp. 324–326.10.1016/0003-2697(78)90350-0Search in Google Scholar PubMed

[42] Roh, C., and U. Jung, Screening of crude plant extracts with anti-obesity activity, International Journal of Molecular Sciences, Vol. 13, 2012, pp. 1710–1719.10.3390/ijms13021710Search in Google Scholar PubMed PubMed Central

[43] Wickramaratne, M. N., J. C. Punchihewa, and D. B.M. Wickramaratne. In-vitro alpha amylase inhibitory activity of the leaf extracts of Adenanthera pavonina. BMC Complementary and Alternative Medicine, Vol. 16, 2016, p. 466.10.1186/s12906-016-1452-ySearch in Google Scholar PubMed PubMed Central

[44] Pistia-Brueggeman, G. and R. I. Hollingsworth. A preparation and screening strategy for glycosidase inhibitors. Tetrahedron, Vol. 57, 2001, pp. 8773–8778.10.1016/S0040-4020(01)00877-8Search in Google Scholar

[45] Magaldi, S., S. Mata-Essayag, C. Hartung de Capriles, C. Perez, M. T. Colella, C. Olaizola, et al. Well diffusion for antifungal susceptibility testing. International Journal of Infectious Diseases, Vol. 8, 2004, pp. 39–45.10.1016/j.ijid.2003.03.002Search in Google Scholar PubMed

[46] Brown, W. J. National committee for clinical laboratory standards agar dilution susceptibility testing of anaerobic gram-negative bacteria. Antimicrobial Agents and Chemotherapy, Vol. 32, 1988, pp. 385–390.10.1128/AAC.32.3.385Search in Google Scholar PubMed PubMed Central

[47] Antunes, A. L.S., D. S. Trentin, J. W. Bonfanti, C. C.F. Pinto, L. R.R. Perez, A. J. Macedo, et al. Application of a feasible method for determination of biofilm antimicrobial susceptibility in staphylococci. APMIS, Vol. 118, 2010, pp. 873–877.10.1111/j.1600-0463.2010.02681.xSearch in Google Scholar PubMed

[48] Min, W.-H., X.-B. Fang, T. Wu, L. Fang, C.-L. Liu, J. Wang, Characterization and antioxidant activity of an acidic exopolysaccharide from Lactobacillus plantarum JLAU103. Journal of Bioscience and Bioengineering, Vol. 127, 2019, pp. 758–766.10.1016/j.jbiosc.2018.12.004Search in Google Scholar PubMed

[49] Giménez-Bastida, J. A., T. Shibata, K. Uchida, and C. Schneider. Roles of 5-lipoxygenase and cyclooxygenase-2 in the biosynthesis of hemiketals E2 and D2 by activated human leukocytes. FASEB Journal, Vol. 31, 2017, pp. 1867–1878.10.1096/fj.201601136RSearch in Google Scholar PubMed PubMed Central

[50] Attiq, A., J. Jalil, K. Husain, and W. Ahmad. Raging the war against inflammation with natural products. Frontiers in Pharmacology, Vol. 9, 2018, id. 976.10.3389/fphar.2018.00976Search in Google Scholar PubMed PubMed Central

[51] Jenab, A., R. Roghanian, and G. Emtiazi. Bacterial natural compounds with anti-inflammatory and immunomodulatory properties (Mini Review). Drug design, Development and Therapy, Vol. 14, 2020, pp. 3787–3801.10.2147/DDDT.S261283Search in Google Scholar PubMed PubMed Central

[52] Čolović, M. B., D. Z. Krstić, T. D. Lazarević-Pašti, A. M. Bondžić, and V. M. Vasić. Acetylcholinesterase Inhibitors: Pharmacology and Toxicology. Current Neuropharmacology, Vol. 11, 2013, pp. 315–335.10.2174/1570159X11311030006Search in Google Scholar

[53] Nordberg, A., C. Ballard, R. Bullock, T. Darreh-Shori, and M. Somogyi. A review of butyrylcholinesterase as a therapeutic target in the treatment of alzheimer’s diseaseprim. The primary care companion for CNS disorders, Vol. 15, No. 2, 2013, id. 12r01412.10.4088/PCC.12r01412Search in Google Scholar

[54] Almasi, F., F. Mohammadipanah, H.-R. Adhami, and J. Hamedi. Introduction of marine-derived Streptomyces sp. UTMC 1334 as a source of pyrrole derivatives with anti-acetylcholinesterase activity. Journal of Applied Microbiology, Vol. 125, 2018, pp. 1370–1382.10.1111/jam.14043Search in Google Scholar

[55] Gangalla, R., S. Gattu, S. Palaniappan, M. Ahamed, B. Macha, R. K. Thampu, et al. Structural characterisation and assessment of the novel Bacillus amyloliquefaciens rk3 exopolysaccharide on the improvement of cognitive function in alzheimer’s disease mice. Polymers, Vol. 13, 2021, id. 2842.10.3390/polym13172842Search in Google Scholar

[56] Pasinetti, G. M. Cyclooxygenase and inflammation in Alzheimer’s disease: experimental approaches and clinical interventions. Journal of Neuroscience Research, Vol. 54, 1998, pp. 1–6.10.1002/(SICI)1097-4547(19981001)54:1<1::AID-JNR1>3.3.CO;2-2Search in Google Scholar

[57] Dilna, S. V., H. Surya, R. G. Aswathy, K. K. Varsha, D. N. Sakthikumar, A. Pandey, et al. Characterization of an exopolysaccharide with potential health-benefit properties from a probiotic Lactobacillus plantarum RJF4. LWT-Food Science and Technology, Vol. 64, 2015, pp. 1179–1186.10.1016/j.lwt.2015.07.040Search in Google Scholar

[58] Sasikumar, K., D. Kozhummal Vaikkath, L. Devendra, and K. M. Nampoothiri. An exopolysaccharide (EPS) from a Lactobacillus plantarum BR2 with potential benefits for making functional foods. Bioresource Technology, Vol. 241, 2017, pp. 1152–1156.10.1016/j.biortech.2017.05.075Search in Google Scholar

[59] Korcz, E. and L. Varga. Exopolysaccharides from lactic acid bacteria: Techno-functional application in the food industry. Trends in Food Science and Technology, Vol. 110, 2021, pp. 375–384.10.1016/j.tifs.2021.02.014Search in Google Scholar

[60] Al-Dhaheri, A. S., R. Al-Hemeiri, J. Kizhakkayil, A. Al-Nabulsi, A. Abushelaibi, N. P. Shah, et al. Health-promoting benefits of low-fat akawi cheese made by exopolysaccharide-producing probiotic Lactobacillus plantarum isolated from camel milk. Journal of Dairy Science, Vol. 100, 2017, pp. 7771–7779.10.3168/jds.2017-12761Search in Google Scholar

[61] Asano, N. Glycosidase inhibitors: update and perspectives on practical use. Glycobiology, Vol. 13, 2003, pp. 93R–104R.10.1093/glycob/cwg090Search in Google Scholar

[62] Kumar, R. V. and V. R. Sinha. Newer insights into the drug delivery approaches of α-glucosidase inhibitors. Expert Opinion on Drug Delivery, Vol. 9, 2012, pp. 403–416.10.1517/17425247.2012.663080Search in Google Scholar PubMed

[63] Pujiyanto, S., M. Resdiani, B. Raharja, and R. S. Ferniah. A-Amylase inhibitor activity of endophytic bacteria isolated from Annona muricata L. Journal of Physics: Conference Series, Vol. 1025, 2018, id. 012085.10.1088/1742-6596/1025/1/012085Search in Google Scholar

[64] Levison, M. E. Pharmacodynamics of antimicrobial drugs. Infectious Disease Clinics of North America, Vol. 18, 2004, pp. 451–465.10.1016/j.idc.2004.04.012Search in Google Scholar PubMed

[65] Thomas, B., A. Adeleke, R. Raheem-Ademola, R. Kolawole, and O. Musa. Efficiency of some disinfectants on bacterial wound pathogens. Life Science Journal, Vol. 9, 2012, pp. 752–755.Search in Google Scholar

[66] Drira, M., J. Elleuch, H. Ben Hlima, F. Hentati, C. Gardarin, C. Rihouey, et al. Optimization of exopolysaccharides production by porphyridium sordidum and their potential to induce defense responses in arabidopsis thaliana against Fusarium oxysporum. Biomolecules, Vol. 11, 2021, id. 282.10.3390/biom11020282Search in Google Scholar PubMed PubMed Central

[67] Rajoka, M. S.R., H. M. Mehwish, H. F. Hayat, N. Hussain, S. Sarwar, H. Aslam, et al. Characterization, the antioxidant and antimicrobial activity of exopolysaccharide isolated from poultry origin lactobacilli. Probiotics and Antimicrobial Proteins, Vol. 11, 2019, pp. 1132–1142.10.1007/s12602-018-9494-8Search in Google Scholar PubMed

[68] Zhou, Y., Y. Cui, and X. Qu. Exopolysaccharides of lactic acid bacteria: Structure, bioactivity and associations: A review. Carbohydrate Polymers, Vol. 207, 2019, pp. 317–332.10.1016/j.carbpol.2018.11.093Search in Google Scholar PubMed

[69] Nehal, F., M. Sahnoun, S. Smaoui, B. Jaouadi, S. Bejar, and S. Mohammed. Characterization, high production and antimicrobial activity of exopolysaccharides from Lactococcus lactis F-mou. Microbial Pathogenesis, Vol. 132, 2019, pp. 10–19.10.1016/j.micpath.2019.04.018Search in Google Scholar PubMed

[70] Sivasankar, P., P. Seedevi, S. Poongodi, M. Sivakumar, T. Murugan, L. Sivakumar, et al. Characterization, antimicrobial and antioxidant property of exopolysaccharide mediated silver nanoparticles synthesized by Streptomyces violaceus MM72. Carbohydrate Polymers, Vol. 181, 2018, pp. 752–759.10.1016/j.carbpol.2017.11.082Search in Google Scholar PubMed

[71] Medrano, M., M. F. Hamet, A. G. Abraham, and P. F. Pérez. Kefiran protects Caco-2 cells from cytopathic effects induced by Bacillus cereus infection. Antonie Van Leeuwenhoek, Vol. 96, 2009, pp. 505–513.10.1007/s10482-009-9366-zSearch in Google Scholar PubMed

[72] Dave, S. R., K. H. Upadhyay, A. M. Vaishnav, and D. R. Tipre. Exopolysaccharides from marine bacteria: production, recovery and applications. Environmental Sustainability, Vol. 3, 2020, pp. 139–154.10.1007/s42398-020-00101-5Search in Google Scholar

[73] Yang, M., J. Yun, H. Zhang, T. A. Magocha, H. Zabed, Y. Xue, et al. Genetically engineered strains: application and advances for 1,3-propanediol production from glycerol. Food Technology and Biotechnology, Vol. 56, 2018, pp. 3–15.Search in Google Scholar

[74] Levander, F., M. Svensson, and P. Rådström. Enhanced exopolysaccharide production by metabolic engineering of Streptococcus thermophilus. Applied and Environmental Microbiology, Vol. 68, 2002, pp. 784–790.10.1128/AEM.68.2.784-790.2002Search in Google Scholar PubMed PubMed Central

Received: 2023-11-16
Revised: 2024-03-31
Accepted: 2024-04-03
Published Online: 2024-05-08

© 2024 the author(s), published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

  1. Review Articles
  2. Effect of superplasticizer in geopolymer and alkali-activated cement mortar/concrete: A review
  3. Experimenting the influence of corncob ash on the mechanical strength of slag-based geopolymer concrete
  4. Powder metallurgy processing of high entropy alloys: Bibliometric analysis and systematic review
  5. Exploring the potential of agricultural waste as an additive in ultra-high-performance concrete for sustainable construction: A comprehensive review
  6. A review on partial substitution of nanosilica in concrete
  7. Foam concrete for lightweight construction applications: A comprehensive review of the research development and material characteristics
  8. Modification of PEEK for implants: Strategies to improve mechanical, antibacterial, and osteogenic properties
  9. Interfacing the IoT in composite manufacturing: An overview
  10. Advances in processing and ablation properties of carbon fiber reinforced ultra-high temperature ceramic composites
  11. Advancing auxetic materials: Emerging development and innovative applications
  12. Revolutionizing energy harvesting: A comprehensive review of thermoelectric devices
  13. Exploring polyetheretherketone in dental implants and abutments: A focus on biomechanics and finite element methods
  14. Smart technologies and textiles and their potential use and application in the care and support of elderly individuals: A systematic review
  15. Reinforcement mechanisms and current research status of silicon carbide whisker-reinforced composites: A comprehensive review
  16. Innovative eco-friendly bio-composites: A comprehensive review of the fabrication, characterization, and applications
  17. Review on geopolymer concrete incorporating Alccofine-1203
  18. Advancements in surface treatments for aluminum alloys in sports equipment
  19. Ionic liquid-modified carbon-based fillers and their polymer composites – A Raman spectroscopy analysis
  20. Emerging boron nitride nanosheets: A review on synthesis, corrosion resistance coatings, and their impacts on the environment and health
  21. Mechanism, models, and influence of heterogeneous factors of the microarc oxidation process: A comprehensive review
  22. Synthesizing sustainable construction paradigms: A comprehensive review and bibliometric analysis of granite waste powder utilization and moisture correction in concrete
  23. 10.1515/rams-2025-0086
  24. Research Articles
  25. Coverage and reliability improvement of copper metallization layer in through hole at BGA area during load board manufacture
  26. Study on dynamic response of cushion layer-reinforced concrete slab under rockfall impact based on smoothed particle hydrodynamics and finite-element method coupling
  27. Study on the mechanical properties and microstructure of recycled brick aggregate concrete with waste fiber
  28. Multiscale characterization of the UV aging resistance and mechanism of light stabilizer-modified asphalt
  29. Characterization of sandwich materials – Nomex-Aramid carbon fiber performances under mechanical loadings: Nonlinear FE and convergence studies
  30. Effect of grain boundary segregation and oxygen vacancy annihilation on aging resistance of cobalt oxide-doped 3Y-TZP ceramics for biomedical applications
  31. Mechanical damage mechanism investigation on CFRP strengthened recycled red brick concrete
  32. Finite element analysis of deterioration of axial compression behavior of corroded steel-reinforced concrete middle-length columns
  33. Grinding force model for ultrasonic assisted grinding of γ-TiAl intermetallic compounds and experimental validation
  34. Enhancement of hardness and wear strength of pure Cu and Cu–TiO2 composites via a friction stir process while maintaining electrical resistivity
  35. Effect of sand–precursor ratio on mechanical properties and durability of geopolymer mortar with manufactured sand
  36. Research on the strength prediction for pervious concrete based on design porosity and water-to-cement ratio
  37. Development of a new damping ratio prediction model for recycled aggregate concrete: Incorporating modified admixtures and carbonation effects
  38. Exploring the viability of AI-aided genetic algorithms in estimating the crack repair rate of self-healing concrete
  39. Modification of methacrylate bone cement with eugenol – A new material with antibacterial properties
  40. Numerical investigations on constitutive model parameters of HRB400 and HTRB600 steel bars based on tensile and fatigue tests
  41. Research progress on Fe3+-activated near-infrared phosphor
  42. Discrete element simulation study on effects of grain preferred orientation on micro-cracking and macro-mechanical behavior of crystalline rocks
  43. Ultrasonic resonance evaluation method for deep interfacial debonding defects of multilayer adhesive bonded materials
  44. Effect of impurity components in titanium gypsum on the setting time and mechanical properties of gypsum-slag cementitious materials
  45. Bending energy absorption performance of composite fender piles with different winding angles
  46. Theoretical study of the effect of orientations and fibre volume on the thermal insulation capability of reinforced polymer composites
  47. Synthesis and characterization of a novel ternary magnetic composite for the enhanced adsorption capacity to remove organic dyes
  48. Couple effects of multi-impact damage and CAI capability on NCF composites
  49. Mechanical testing and engineering applicability analysis of SAP concrete used in buffer layer design for tunnels in active fault zones
  50. Investigating the rheological characteristics of alkali-activated concrete using contemporary artificial intelligence approaches
  51. Integrating micro- and nanowaste glass with waste foundry sand in ultra-high-performance concrete to enhance material performance and sustainability
  52. Effect of water immersion on shear strength of epoxy adhesive filled with graphene nanoplatelets
  53. Impact of carbon content on the phase structure and mechanical properties of TiBCN coatings via direct current magnetron sputtering
  54. Investigating the anti-aging properties of asphalt modified with polyphosphoric acid and tire pyrolysis oil
  55. Biomedical and therapeutic potential of marine-derived Pseudomonas sp. strain AHG22 exopolysaccharide: A novel bioactive microbial metabolite
  56. Effect of basalt fiber length on the behavior of natural hydraulic lime-based mortars
  57. Optimizing the performance of TPCB/SCA composite-modified asphalt using improved response surface methodology
  58. Compressive strength of waste-derived cementitious composites using machine learning
  59. Melting phenomenon of thermally stratified MHD Powell–Eyring nanofluid with variable porosity past a stretching Riga plate
  60. Development and characterization of a coaxial strain-sensing cable integrated steel strand for wide-range stress monitoring
  61. Compressive and tensile strength estimation of sustainable geopolymer concrete using contemporary boosting ensemble techniques
  62. Customized 3D printed porous titanium scaffolds with nanotubes loading antibacterial drugs for bone tissue engineering
  63. Facile design of PTFE-kaolin-based ternary nanocomposite as a hydrophobic and high corrosion-barrier coating
  64. Effects of C and heat treatment on microstructure, mechanical, and tribo-corrosion properties of VAlTiMoSi high-entropy alloy coating
  65. Study on the damage mechanism and evolution model of preloaded sandstone subjected to freezing–thawing action based on the NMR technology
  66. Promoting low carbon construction using alkali-activated materials: A modeling study for strength prediction and feature interaction
  67. Entropy generation analysis of MHD convection flow of hybrid nanofluid in a wavy enclosure with heat generation and thermal radiation
  68. Friction stir welding of dissimilar Al–Mg alloys for aerospace applications: Prospects and future potential
  69. Fe nanoparticle-functionalized ordered mesoporous carbon with tailored mesostructures and their applications in magnetic removal of Ag(i)
  70. Study on physical and mechanical properties of complex-phase conductive fiber cementitious materials
  71. Evaluating the strength loss and the effectiveness of glass and eggshell powder for cement mortar under acidic conditions
  72. Effect of fly ash on properties and hydration of calcium sulphoaluminate cement-based materials with high water content
  73. Analyzing the efficacy of waste marble and glass powder for the compressive strength of self-compacting concrete using machine learning strategies
  74. Experimental study on municipal solid waste incineration ash micro-powder as concrete admixture
  75. Parameter optimization for ultrasonic-assisted grinding of γ-TiAl intermetallics: A gray relational analysis approach with surface integrity evaluation
  76. Producing sustainable binding materials using marble waste blended with fly ash and rice husk ash for building materials
  77. Effect of steam curing system on compressive strength of recycled aggregate concrete
  78. A sawtooth constitutive model describing strain hardening and multiple cracking of ECC under uniaxial tension
  79. Predicting mechanical properties of sustainable green concrete using novel machine learning: Stacking and gene expression programming
  80. Toward sustainability: Integrating experimental study and data-driven modeling for eco-friendly paver blocks containing plastic waste
  81. A numerical analysis of the rotational flow of a hybrid nanofluid past a unidirectional extending surface with velocity and thermal slip conditions
  82. A magnetohydrodynamic flow of a water-based hybrid nanofluid past a convectively heated rotating disk surface: A passive control of nanoparticles
  83. Prediction of flexural strength of concrete with eggshell and glass powders: Advanced cutting-edge approach for sustainable materials
  84. Efficacy of sustainable cementitious materials on concrete porosity for enhancing the durability of building materials
  85. Phase and microstructural characterization of swat soapstone (Mg3Si4O10(OH)2)
  86. Effect of waste crab shell powder on matrix asphalt
  87. Improving effect and mechanism on service performance of asphalt binder modified by PW polymer
  88. Influence of pH on the synthesis of carbon spheres and the application of carbon sphere-based solid catalysts in esterification
  89. Experimenting the compressive performance of low-carbon alkali-activated materials using advanced modeling techniques
  90. Thermogravimetric (TG/DTG) characterization of cold-pressed oil blends and Saccharomyces cerevisiae-based microcapsules obtained with them
  91. Investigation of temperature effect on thermo-mechanical property of carbon fiber/PEEK composites
  92. Computational approaches for structural analysis of wood specimens
  93. Integrated structure–function design of 3D-printed porous polydimethylsiloxane for superhydrophobic engineering
  94. Exploring the impact of seashell powder and nano-silica on ultra-high-performance self-curing concrete: Insights into mechanical strength, durability, and high-temperature resilience
  95. Axial compression damage constitutive model and damage characteristics of fly ash/silica fume modified magnesium phosphate cement after being treated at different temperatures
  96. Integrating testing and modeling methods to examine the feasibility of blended waste materials for the compressive strength of rubberized mortar
  97. Special Issue on 3D and 4D Printing of Advanced Functional Materials - Part II
  98. Energy absorption of gradient triply periodic minimal surface structure manufactured by stereolithography
  99. Marine polymers in tissue bioprinting: Current achievements and challenges
  100. Quick insight into the dynamic dimensions of 4D printing in polymeric composite mechanics
  101. Recent advances in 4D printing of hydrogels
  102. Mechanically sustainable and primary recycled thermo-responsive ABS–PLA polymer composites for 4D printing applications: Fabrication and studies
  103. Special Issue on Materials and Technologies for Low-carbon Biomass Processing and Upgrading
  104. Low-carbon embodied alkali-activated materials for sustainable construction: A comparative study of single and ensemble learners
  105. Study on bending performance of prefabricated glulam-cross laminated timber composite floor
  106. Special Issue on Recent Advancement in Low-carbon Cement-based Materials - Part I
  107. Supplementary cementitious materials-based concrete porosity estimation using modeling approaches: A comparative study of GEP and MEP
  108. Modeling the strength parameters of agro waste-derived geopolymer concrete using advanced machine intelligence techniques
  109. Promoting the sustainable construction: A scientometric review on the utilization of waste glass in concrete
  110. Incorporating geranium plant waste into ultra-high performance concrete prepared with crumb rubber as fine aggregate in the presence of polypropylene fibers
  111. Investigation of nano-basic oxygen furnace slag and nano-banded iron formation on properties of high-performance geopolymer concrete
  112. Effect of incorporating ultrafine palm oil fuel ash on the resistance to corrosion of steel bars embedded in high-strength green concrete
  113. Influence of nanomaterials on properties and durability of ultra-high-performance geopolymer concrete
  114. Influence of palm oil ash and palm oil clinker on the properties of lightweight concrete
https://doi.org/10.1515/rams-2024-0016
Keywords for this article
antioxidant; anti-inflammatory; antidiabetic; anti-obesity; antibiofilm; anti-Alzheimer
Creative Commons
BY 4.0

Articles in the same Issue

  1. Review Articles
  2. Effect of superplasticizer in geopolymer and alkali-activated cement mortar/concrete: A review
  3. Experimenting the influence of corncob ash on the mechanical strength of slag-based geopolymer concrete
  4. Powder metallurgy processing of high entropy alloys: Bibliometric analysis and systematic review
  5. Exploring the potential of agricultural waste as an additive in ultra-high-performance concrete for sustainable construction: A comprehensive review
  6. A review on partial substitution of nanosilica in concrete
  7. Foam concrete for lightweight construction applications: A comprehensive review of the research development and material characteristics
  8. Modification of PEEK for implants: Strategies to improve mechanical, antibacterial, and osteogenic properties
  9. Interfacing the IoT in composite manufacturing: An overview
  10. Advances in processing and ablation properties of carbon fiber reinforced ultra-high temperature ceramic composites
  11. Advancing auxetic materials: Emerging development and innovative applications
  12. Revolutionizing energy harvesting: A comprehensive review of thermoelectric devices
  13. Exploring polyetheretherketone in dental implants and abutments: A focus on biomechanics and finite element methods
  14. Smart technologies and textiles and their potential use and application in the care and support of elderly individuals: A systematic review
  15. Reinforcement mechanisms and current research status of silicon carbide whisker-reinforced composites: A comprehensive review
  16. Innovative eco-friendly bio-composites: A comprehensive review of the fabrication, characterization, and applications
  17. Review on geopolymer concrete incorporating Alccofine-1203
  18. Advancements in surface treatments for aluminum alloys in sports equipment
  19. Ionic liquid-modified carbon-based fillers and their polymer composites – A Raman spectroscopy analysis
  20. Emerging boron nitride nanosheets: A review on synthesis, corrosion resistance coatings, and their impacts on the environment and health
  21. Mechanism, models, and influence of heterogeneous factors of the microarc oxidation process: A comprehensive review
  22. Synthesizing sustainable construction paradigms: A comprehensive review and bibliometric analysis of granite waste powder utilization and moisture correction in concrete
  23. 10.1515/rams-2025-0086
  24. Research Articles
  25. Coverage and reliability improvement of copper metallization layer in through hole at BGA area during load board manufacture
  26. Study on dynamic response of cushion layer-reinforced concrete slab under rockfall impact based on smoothed particle hydrodynamics and finite-element method coupling
  27. Study on the mechanical properties and microstructure of recycled brick aggregate concrete with waste fiber
  28. Multiscale characterization of the UV aging resistance and mechanism of light stabilizer-modified asphalt
  29. Characterization of sandwich materials – Nomex-Aramid carbon fiber performances under mechanical loadings: Nonlinear FE and convergence studies
  30. Effect of grain boundary segregation and oxygen vacancy annihilation on aging resistance of cobalt oxide-doped 3Y-TZP ceramics for biomedical applications
  31. Mechanical damage mechanism investigation on CFRP strengthened recycled red brick concrete
  32. Finite element analysis of deterioration of axial compression behavior of corroded steel-reinforced concrete middle-length columns
  33. Grinding force model for ultrasonic assisted grinding of γ-TiAl intermetallic compounds and experimental validation
  34. Enhancement of hardness and wear strength of pure Cu and Cu–TiO2 composites via a friction stir process while maintaining electrical resistivity
  35. Effect of sand–precursor ratio on mechanical properties and durability of geopolymer mortar with manufactured sand
  36. Research on the strength prediction for pervious concrete based on design porosity and water-to-cement ratio
  37. Development of a new damping ratio prediction model for recycled aggregate concrete: Incorporating modified admixtures and carbonation effects
  38. Exploring the viability of AI-aided genetic algorithms in estimating the crack repair rate of self-healing concrete
  39. Modification of methacrylate bone cement with eugenol – A new material with antibacterial properties
  40. Numerical investigations on constitutive model parameters of HRB400 and HTRB600 steel bars based on tensile and fatigue tests
  41. Research progress on Fe3+-activated near-infrared phosphor
  42. Discrete element simulation study on effects of grain preferred orientation on micro-cracking and macro-mechanical behavior of crystalline rocks
  43. Ultrasonic resonance evaluation method for deep interfacial debonding defects of multilayer adhesive bonded materials
  44. Effect of impurity components in titanium gypsum on the setting time and mechanical properties of gypsum-slag cementitious materials
  45. Bending energy absorption performance of composite fender piles with different winding angles
  46. Theoretical study of the effect of orientations and fibre volume on the thermal insulation capability of reinforced polymer composites
  47. Synthesis and characterization of a novel ternary magnetic composite for the enhanced adsorption capacity to remove organic dyes
  48. Couple effects of multi-impact damage and CAI capability on NCF composites
  49. Mechanical testing and engineering applicability analysis of SAP concrete used in buffer layer design for tunnels in active fault zones
  50. Investigating the rheological characteristics of alkali-activated concrete using contemporary artificial intelligence approaches
  51. Integrating micro- and nanowaste glass with waste foundry sand in ultra-high-performance concrete to enhance material performance and sustainability
  52. Effect of water immersion on shear strength of epoxy adhesive filled with graphene nanoplatelets
  53. Impact of carbon content on the phase structure and mechanical properties of TiBCN coatings via direct current magnetron sputtering
  54. Investigating the anti-aging properties of asphalt modified with polyphosphoric acid and tire pyrolysis oil
  55. Biomedical and therapeutic potential of marine-derived Pseudomonas sp. strain AHG22 exopolysaccharide: A novel bioactive microbial metabolite
  56. Effect of basalt fiber length on the behavior of natural hydraulic lime-based mortars
  57. Optimizing the performance of TPCB/SCA composite-modified asphalt using improved response surface methodology
  58. Compressive strength of waste-derived cementitious composites using machine learning
  59. Melting phenomenon of thermally stratified MHD Powell–Eyring nanofluid with variable porosity past a stretching Riga plate
  60. Development and characterization of a coaxial strain-sensing cable integrated steel strand for wide-range stress monitoring
  61. Compressive and tensile strength estimation of sustainable geopolymer concrete using contemporary boosting ensemble techniques
  62. Customized 3D printed porous titanium scaffolds with nanotubes loading antibacterial drugs for bone tissue engineering
  63. Facile design of PTFE-kaolin-based ternary nanocomposite as a hydrophobic and high corrosion-barrier coating
  64. Effects of C and heat treatment on microstructure, mechanical, and tribo-corrosion properties of VAlTiMoSi high-entropy alloy coating
  65. Study on the damage mechanism and evolution model of preloaded sandstone subjected to freezing–thawing action based on the NMR technology
  66. Promoting low carbon construction using alkali-activated materials: A modeling study for strength prediction and feature interaction
  67. Entropy generation analysis of MHD convection flow of hybrid nanofluid in a wavy enclosure with heat generation and thermal radiation
  68. Friction stir welding of dissimilar Al–Mg alloys for aerospace applications: Prospects and future potential
  69. Fe nanoparticle-functionalized ordered mesoporous carbon with tailored mesostructures and their applications in magnetic removal of Ag(i)
  70. Study on physical and mechanical properties of complex-phase conductive fiber cementitious materials
  71. Evaluating the strength loss and the effectiveness of glass and eggshell powder for cement mortar under acidic conditions
  72. Effect of fly ash on properties and hydration of calcium sulphoaluminate cement-based materials with high water content
  73. Analyzing the efficacy of waste marble and glass powder for the compressive strength of self-compacting concrete using machine learning strategies
  74. Experimental study on municipal solid waste incineration ash micro-powder as concrete admixture
  75. Parameter optimization for ultrasonic-assisted grinding of γ-TiAl intermetallics: A gray relational analysis approach with surface integrity evaluation
  76. Producing sustainable binding materials using marble waste blended with fly ash and rice husk ash for building materials
  77. Effect of steam curing system on compressive strength of recycled aggregate concrete
  78. A sawtooth constitutive model describing strain hardening and multiple cracking of ECC under uniaxial tension
  79. Predicting mechanical properties of sustainable green concrete using novel machine learning: Stacking and gene expression programming
  80. Toward sustainability: Integrating experimental study and data-driven modeling for eco-friendly paver blocks containing plastic waste
  81. A numerical analysis of the rotational flow of a hybrid nanofluid past a unidirectional extending surface with velocity and thermal slip conditions
  82. A magnetohydrodynamic flow of a water-based hybrid nanofluid past a convectively heated rotating disk surface: A passive control of nanoparticles
  83. Prediction of flexural strength of concrete with eggshell and glass powders: Advanced cutting-edge approach for sustainable materials
  84. Efficacy of sustainable cementitious materials on concrete porosity for enhancing the durability of building materials
  85. Phase and microstructural characterization of swat soapstone (Mg3Si4O10(OH)2)
  86. Effect of waste crab shell powder on matrix asphalt
  87. Improving effect and mechanism on service performance of asphalt binder modified by PW polymer
  88. Influence of pH on the synthesis of carbon spheres and the application of carbon sphere-based solid catalysts in esterification
  89. Experimenting the compressive performance of low-carbon alkali-activated materials using advanced modeling techniques
  90. Thermogravimetric (TG/DTG) characterization of cold-pressed oil blends and Saccharomyces cerevisiae-based microcapsules obtained with them
  91. Investigation of temperature effect on thermo-mechanical property of carbon fiber/PEEK composites
  92. Computational approaches for structural analysis of wood specimens
  93. Integrated structure–function design of 3D-printed porous polydimethylsiloxane for superhydrophobic engineering
  94. Exploring the impact of seashell powder and nano-silica on ultra-high-performance self-curing concrete: Insights into mechanical strength, durability, and high-temperature resilience
  95. Axial compression damage constitutive model and damage characteristics of fly ash/silica fume modified magnesium phosphate cement after being treated at different temperatures
  96. Integrating testing and modeling methods to examine the feasibility of blended waste materials for the compressive strength of rubberized mortar
  97. Special Issue on 3D and 4D Printing of Advanced Functional Materials - Part II
  98. Energy absorption of gradient triply periodic minimal surface structure manufactured by stereolithography
  99. Marine polymers in tissue bioprinting: Current achievements and challenges
  100. Quick insight into the dynamic dimensions of 4D printing in polymeric composite mechanics
  101. Recent advances in 4D printing of hydrogels
  102. Mechanically sustainable and primary recycled thermo-responsive ABS–PLA polymer composites for 4D printing applications: Fabrication and studies
  103. Special Issue on Materials and Technologies for Low-carbon Biomass Processing and Upgrading
  104. Low-carbon embodied alkali-activated materials for sustainable construction: A comparative study of single and ensemble learners
  105. Study on bending performance of prefabricated glulam-cross laminated timber composite floor
  106. Special Issue on Recent Advancement in Low-carbon Cement-based Materials - Part I
  107. Supplementary cementitious materials-based concrete porosity estimation using modeling approaches: A comparative study of GEP and MEP
  108. Modeling the strength parameters of agro waste-derived geopolymer concrete using advanced machine intelligence techniques
  109. Promoting the sustainable construction: A scientometric review on the utilization of waste glass in concrete
  110. Incorporating geranium plant waste into ultra-high performance concrete prepared with crumb rubber as fine aggregate in the presence of polypropylene fibers
  111. Investigation of nano-basic oxygen furnace slag and nano-banded iron formation on properties of high-performance geopolymer concrete
  112. Effect of incorporating ultrafine palm oil fuel ash on the resistance to corrosion of steel bars embedded in high-strength green concrete
  113. Influence of nanomaterials on properties and durability of ultra-high-performance geopolymer concrete
  114. Influence of palm oil ash and palm oil clinker on the properties of lightweight concrete
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 26.10.2025 from https://www.degruyterbrill.com/document/doi/10.1515/rams-2024-0016/html?lang=en&srsltid=AfmBOor6KiJKHVFzVhgZINv0kX16oQ_8LvdC0-eP3gG6Fwhxme0kKlmW
Scroll to top button