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Antiplasmodial Activity of Stigmastane Steroids from Dryobalanops oblongifolia Stem Bark

  • Indriani Indriani , Nanik Siti Aminah EMAIL logo and Ni Nyoman Tri Puspaningsih
Published/Copyright: April 7, 2020
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Open Chemistry
From the journal Open Chemistry Volume 18 Issue 1

Abstract

Three stigmastane steroids: 6-hydroxystigmast-4-en-3-one (1), stigmast-4-en-3-one (2), and 3-hydroxystigmast-5-en-7-one (3) were successfully isolated from the acetone extract of Dryobalanps oblongifolia stem bark. The structural determination of isolated compounds was carried out on the basis of data analysis of NMR and MS spectra. In order to identify the antiplasmodial activity, the isolated compound was put to test against Plasmodium falciparum 3D7. Antiplasmodial activity of the isolated compounds showed that the IC50 values of 6-hydroxystigmast-4-en-3-one were 37.29 μg/mL while the IC50 values of stigmast-4-en-3-one were 43.54 μg/mL and the IC50 values of 3-hydroxystigmast-5-en-7-one were 13.34 μg/mL (chloroquine phosphate was used as a positive control, IC50 0.006 μg/mL). Judging from the results, the isolated compounds were proven to demonstrate mediocre antiplasmodial activity. Compound (3) indicated a better antimalarial activity than compound (1) and (2), even though there was no satisfactory activity that indicated its ability to combat chloroquine. Therefore, it might not be developed as an antimalarial drug.

Keywords: Antiplasmodial; Dryobalanops oblongifolia; Plasmodium falciparum; Stigmastane steroid

1 Introduction

Malaria is one of the infectious diseases that has become a major problem of health. It is found in nearly most of all tropics, particularly developing and poor countries. Plasmodium, a parasitic protozoa genus, is what causes malaria in humans. The parasite that derived from the genus namely Plasmodium falciparum is the lethal part that causes acute infection worldwide with an annual death toll of 1-2 million people [1, 2].

Quinine which isolated from cinchona tree has been widely used to cure malaria, yet it is still powerless to comprehensively break the life cycle of Plasmodium parasites [3]. Artemisinin, a sesquiterpene lactone, is reported as a potential antimalarial drug and have the ability to kill all phases of the parasites’ life cycle through interaction with heme, yet animal experiment shows neurotoxic and cardiotoxic effect [4]. Development of synthesized drugs, such as chloroquin, pyrimethamine, cycloguanil, and sulfadoxine, have indicated the decline of effectivity caused by the resistance of Plasmodium [3,5,6,7]. Therefore, it is crucial to develop alternative medicines from plants by constituent exploration as potential antimalarial drugs.

Dryobalanops oblongifolia belongs to the family of Dipterocarpaceae and is widely found in Indonesia and Malaysia [8].The phytochemical screening of fruit of D. oblongifolia revaled the presence of steroids compounds in this species[9]. Dryobalanops is known to produce oligostilbene constituents with various interesting activity such as antibacterial, antioxidant, antimalarial and cytotoxic [10, 11, 12, 13, 14]. In continuation for searching bioactive compounds from Indonesia’s plants, a study towards D. oblongifolia was conducted by isolating the agents and examining the antiplasmodial activity against Plasmodium falciparum 3D7. Based on our knowledge this three stigmastane steroids (1-3) were first report from family Dipterocarpaceae and these isolated metabolites expressed only moderate antiplasmodial activity.

2 Experimental section

2.1 General procedures

Firstly, CDCl3 was used to dissolve 1H and 13C NMR and 2D NMR of stigmastane steroids spectra. While using TMS as the internal standard, JEOL J-500 spectrometer was used to record and it was utilized in CDCl3 at 125 MHz (13C) and 500 MHz (1H). On a TSQ Quantum Access MAX Triple Quadrupole Mass Spectrometer, mass spectrometry was analyzed. Gravitation column chromatography (GCC) was conducted with Merck Si gel 60 (700-200 mesh). Vacuum liquid chromatography (VLC) and radial chromatography were conducted using Si gel 60 PF254 and Si gel 60 GF254. The analysis of Thin Layer Chromatography (TLC) was done on Merck kieselgel 60 GF254, precoated Si gel plates, with a thickness of 0.25 mm. This research used already distilled analytical and technical grade solvents.

2.2 Plant Material

Mount Mali was the place where D. oblongifolia Dyer stem bark was originally collected. The mount is located in Tempunak, Sintang, West Kalimantan of Indonesia. The researchers then proceeded to the identification step by sending the plant specimen to the Biological Research Center of LIPI in Bogor, Indonesia. A voucher specimen was put in safekeeping at the herbarium.

2.3 Extraction and Isolation

At room temperature, as much as 5 kg of D. oblongifolia stem bark powder was pulped twice in acetone. It is meant to afford the extraction of brownish gummy after the process of vacuum evaporation. The extract was subsequently separated into 2 fractions: 1 fraction is able to be dissolved in acetone – diethyl ether while the other fraction is insoluble. As much as 48 g of the soluble fraction was divided into fractions using vacuum liquid chromatography (VLC) (n-hexane – ethyl acetate, enhancing polarity) to give four main fractions which are fraction A-D. By using radial chromatography techniques and Gravitation Colum Chromatography (GCC), as much as 1.7 g of Fraction B was separated and purified. The process led to the production of compound 1 with a total of 6.5 mg and compound 2 with a total of 3 mg. In order to isolate both compounds and enhance the polarity, n-hexane and ethyl acetate mixtures were used. As much as 1.6 g of Fraction C was separated and refined by using the same chromatography techniques and solvent mixtures, resulting in the production of compound 3 with a total of 3.4 mg.

2.3.1 In Vitro Antiplasmodial Assays

The antiplasmodial activity of compound 1-3 was determined in the Tropical Disease Institute of Universitas Airlangga, which is located in Surabaya, Indonesia. In this part, the method used was equivalent with the former method described by Widyawaruyanti et al. [15]. The dissolution of these samples was conducted in DMSO and they were stored at −20°C until use. A culture plate with 24 wells was used to cultivate the P. falciparum clone. The concentration range of each compound was 100, 10, 1, 0.1, and 0.01 μg/mL. As a positive control, a drug with antimalarial characteristics namely Chloroquine phosphate was used. The antiplasmodial activity measurement of compound 1-3 and chloroquine phosphate was calculated in replica. The monitoring process of parasitaemie was conducted when 48 hours had passed by firstly making a blood test fixed with MeOH and spattered with Geimsa (Merck). With the aim to determine the parasitaemia average ratio and average inhibition, the researchers calculated the total number of infected erythrocytes from originally 1000 healthy erythrocytes. The researchers used IC50 value to state the antiplasmodial activity of compound 1-3. IC50 value is the concentration of compounds that causes 50% inhibition of the parasite growth. The IC50 value was obtained by using probit analysis processed by the SPPS program.

Ethical approval: The conducted research is not related to either human or animal use.

3 Result and Discussion

The acetone extracted from D. oblongifolia stem bark was fractionated and purified using radial chromatography, gravitation column chromatography, and vacuum liquid chromatography. It was intended to produce three stigmastane steroid compounds, specifically 6-hydroxystigmast-4-en-3-one (1), stigmast-4-en-3-one (2), and 3-hydroxystigmast-5-en-7-one (3). The isolated compound structures were identified on the basis of 1Hand 13C-NMR spectral data, and 2D NMR experimentations and contrast with the reported data and MS spectral data.

Compound 1 was isolated as an achromatic formless powder. C29H48O2 was established as the molecular formula by means of ESI-MS ([M+H]+ ion at m/z 429.076). There were a total of 6 methyl groups that were found to be present according to the 1H-NMR spectrum. They were 2 groups of tertiary methyl [δH 0.74 (H-18) and 1.38 (H-19)], 3 groups of secondary methyl [δH 0.92 (H-21), 0.81 (H-26), and 0.84 (H-27)], and 1 group of primary methyl δH 0.85 (H-29). Furthermore, 1 oxygenated methine proton was seen at δH 4.35 (H-6), while 1 sp2 methine was seen at δH 5.81(H-4). Meanwhile, it appeared that there was an overlap in the proton peaks of methylene and methine groups. There were 29 carbon signals revealed by the 13C-NMR spectrum that contained an oxygenated secondary carbon at δC 73.3 (C-6), a carbonyl carbon at δC 200.4 (C-3), and 2 olefinic carbons [δC 126.3 (C-4) and 168.5 (C-5)]. There was an indication that the carbon signals that were present at δC 126.3, 168.5, and 200.4 signified an α,β-unsaturated carbonyl system that was present in compound 1. It indicated a suggestion that compound 1 was stigmastane steroid, especially when looking at the data of 1H-NMR and 13C-NMR. There were many correlations that have been pointed out by the spectra of compound 1 Heteronuclear Multiple Bond Correlation (HMBC) particularly between H-21/C-17, H-21/ C-20, and H-21/C-22; H-22/C-23; H-25/C-23, H-25/C-24,H-25/C-27, and H-25/C-28; H-26/C-24, H-26/C-25, and H-26/ C27; H-27/C-25 and H-27/C-26; H-29/C-28. The structure of side chain was established by these correlations. The presence of pentenoperhydrophenanthrene nucleus was indicated by the correlations between H-18/C-12, H-18/C-13, and H-18/C-14; H-19/C-1, H-19/C-5, H-19/C-9, and H-19/C-10, they signified the tetracyclic. In addition, there were indications showed by the HMBC links between H-4 / C-2, H-4 / C-6, H-4 / C-10, and H-6 / C-4, H- 6 / C-8, H-6 / C-10 that there are 2 different locations for the α, β-unsaturated carbonyl system and the hydroxyl group. The location of the former is in ring A, while the latter in ring B (Table 1). Aside from the analysis of the HMBC spectrum, the determination of hydroxyl group location can also be achieved by doing a TOCSY test. Compound 1 structure was indicated as 6-hydroxystigmast-4-en-3-one (Figure 1) [16].

Figure 1 The structure of isolated compounds 1, 2 and 3 from D. oblongifolia.
Figure 1

The structure of isolated compounds 1, 2 and 3 from D. oblongifolia.

Table 1

Avarage Inhibition of isolated compounds (1-3) and Chloroquine phosphate against P. falcifarum 3D7.

NoCompound% Avarage Inhibition (μg/mL)IC50 μg/mLIC50 μM
1001010,10,01
16-hydroxystigmast-4-en-3-one60.7835.1418.4010.261.3637.2986.91
2Stigmast-4-en-3-one58.0634.7620.2811.171.5143.54105.36
33-hydroxystigmast-5-en-7-one72.4042.0826.0912.071.5113.3431.08
4Chloroquine phosphate99.1389.3882.0165.7358.550.0060.01

  1. * The IC50 value was obtained by using probit analysis of SPPS program.

Compound 2 was isolated as an achromatic formless powder with a [M+H]+ ion at m/z 413.244. It was isolated during ESI-MS analysis and it corresponded to C29H48O molecular formula. Compound 2 was discovered by the NMR data as a steroid with stigmastane skeleton. Although compound 2 has a high resemblance with compound 1 in terms of 1H-NMR and 13C-NMR spectrum chemical shifts, compound 2 does not possess any hydroxyl group (Table 1). Compound 2 structure was indicated as stigmast-4-en-3-one (Figure 1) [17, 18].

Compound 3 was isolated too as an achromatic formless powder that has C29H48O2 molecular formula (ESI-MS, [M+H]+ ion at m/z : 429.227). Compound 3 has high resemblance with compound 1 and 2 in terms of NMR spectrum chemical shifts, exposing that compound 3 was a stigmastane steroid. There were 29 carbon signals displayed by 13C-NMR and DEPT spectra. These carbon signals consisted of 6 methyl carbons, 10 methylene carbons, 9 methine carbons, and 3 quaternary carbons, and carbonyl ketone. The HMBC spectra proved that 1 hydroxyl group and the α, β-unsaturated carbonyl system were present with links between H-4/C-2, H-4/C-3, H-4/C-5, H-4/C-6, H-4/C-10 ; H-6/C-4, H-6/C-8, and H-6/C10 ; H-8/ C-7, H-8/C-9. There are indications initiated by the HMBC analysis that the hydroxyl group and the α, β-unsaturated carbonyl system was located on different positions. The location of the former was at the position of C-3 in ring A, while the location of the latter was in ring B (Table 1). Compound 3 structure was identified as 3-hydroxystigmast-5-en-7-one. The confirmation can be seen through a contrast with stigmast 3-hydroxy-5-en-7-one chemical shifts, which is similar to the previously published research (Figure 1) [19, 20].

The examination of antiplasmodial activity against P. falciparum 3D7 was carried out by in vitro to three stigmastane steroid compounds. The test results showe that the IC50 value of 6-hydroxystigmast-4-en-3-one (1) was as much as 37.29 μg/mL. Meanwhile, for stigmast-4-en-3-one (2), the IC50 value was as much as 43.54 μg/mL, whereas the IC50 value of 3-hydroxystigmast-5-en-7-one (3) was as much as 13.34 μg/mL. Chloroquine phosphate was used a positive control with as much as 0.006 μg/mL IC50 (Table 1). Judging from the results, mediocre antiplasmodial activity was found in the three stigmastane steroid compounds [21]. Compound 3 showed better antiplasmodial activity than the others. The structure of stigmastane steroids chemical compound revealed that the presence and position of hydroxyl group can influence their antiplasmodial activity. The location of hydroxyl group in compound 3 is easier to interact with extracellular and intracellular fluids so that it can be easily carried to target molecule [22]. However, compound 3 is considered as lacking the ability to fight against the chloroquine so it may not be promoted as an antimalarial agent.

Tabel 2

6-hydroxystigmast-4-en-3-on (1)

Antimalarial activity of 6-hydroxyistigmast-4-en-3-one against P. falciparum 3D7.

Dose (μg/ml)R% Parasitaemia% Growth% Inhibition% Avarage Inhibition
0 jam48 jam
Kontrol (-)11.174.493.32--
21.174.483.31-
10011.172.451.2861.4560.78
21.172.491.3260.12
1011.173.342.1734.6435.14
21.173.302.1335.65
111.173.862.6918.9818.40
21.173.892.7217.82
0.111.174.152.9810.2410.26
21.174.142.9710.27
0.0111.174.453.281.201.36
21.174.433.261.51
IC5037.29 μg/mL

4 Conclusion

There were three stigmastane steroids that were successfully isolated from the acetone extract derived from the stem bark of Dryobalanops oblongifolia. The evaluation on antiplasmodial activity was performed to all of the isolated compounds, specifically 6-hydroxystigmast-4-en-3-one (1), stigmast-4-en-3-one (2), and 3-hydroxystigmast-5-en-7-one (3). The antiplasmodial activity indicated that there was a total of 37.29 μg/mL of IC50 value in 6-hydroxystigmast-4-en-3-one. Meanwhile, the IC50 value of stigmast-4-en-3-one was as much as 43.54 μg/mL while as much as 13.34 μg/mL of IC50 value was found in 3-hydroxystigmast-5-en-7-one (chloroquine phosphate was used as a positive control, IC50 0.006 μg/mL). Compound 3 was the most active isolated compounds although there was not enough activity to fight against chloroquine. As the consequence, compound 3 did not meet the standard of an antimalarial drug and may not be developed as a proper medication of the disease.

Table 3

Stigmast-4-en-3-one (2)

Antimalarial activity of sistigmast-4-en-3-one against P. falciparum 3D7.

Dose (μg/ml)R% Parasitaemia% Growth% Inhibition% Avarage Inhibition
0 jam48 jam
Kontrol (-)11.004.653.65--
21.004.603.60-
10011.002.531.5357.5058.06
21.002.491.4958.61
1011.003.352.3535.6234.76
21.003.382.3833.89
111.003.912.9120.2720,28
21.003.872.8720.28
0.111.004.213.2112.0611.17
21.004.233.2310.28
0.0111.004.583.581.911.51
21.004.563.561.11
IC5043.54 μg/mL
Tabel 4

3-hydroxysistigmast-5-en-7-one (3)

Antimalarial activity of 3-hydroxystigmast-5-en-7-one against P. falciparum 3D7.

Dose (μg/ml)R% Parasitaemia% Growth% Inhibition% Avarage Inhibition
0 jam48 jam
Kontrol (-)11.174.493.32--
21.174.483.31-
10011.172.090.9272.2972.40
21.172.080.9172.51
1011.173.081.9142.4742.08
21.173.101.9341.69
111.173.642.4725.6026.09
21.173.602.4326.59
0.111.174.102.9311.7512.07
21.174.072.9012.39
0.0111.174.443.271.51151
21.174.433.261.51
IC5013.34 μg/mL

Acknowledgements

We would like to express our gratitude for the grant of “BPPDN” scholarship by Directorate General of Higher Education of Indonesia. Additionally, we are also grateful for the help of identifying the plant specimen by the Biological Research Center staff, LIPI, Bogor, Indonesia.

  1. Conflict of interest: Authors declare no conflict of interest.

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Received: 2018-12-17
Accepted: 2019-12-01
Published Online: 2020-04-07

© 2020 Indriani Indriani et al., published by De Gruyter

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

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  54. Structural cytotoxicity relationship of 2-phenoxy(thiomethyl)pyridotriazolopyrimidines: Quantum chemical calculations and statistical analysis
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  61. Treatment of Parkinson’s disease using focused ultrasound with GDNF retrovirus-loaded microbubbles to open the blood–brain barrier
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  63. Fluorescence biomarkers of malignant melanoma detectable in urine
  64. Study of the remediation effects of passivation materials on Pb-contaminated soil
  65. Saliva proteomic analysis reveals possible biomarkers of renal cell carcinoma
  66. Withania frutescens: Chemical characterization, analgesic, anti-inflammatory, and healing activities
  67. Design, synthesis and pharmacological profile of (−)-verbenone hydrazones
  68. Synthesis of magnesium carbonate hydrate from natural talc
  69. Stability-indicating HPLC-DAD assay for simultaneous quantification of hydrocortisone 21 acetate, dexamethasone, and fluocinolone acetonide in cosmetics
  70. A novel lactose biosensor based on electrochemically synthesized 3,4-ethylenedioxythiophene/thiophene (EDOT/Th) copolymer
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  72. Development and validation of a high performance liquid chromatography/diode array detection method for estrogen determination: Application to residual analysis in meat products
  73. PCSK9 concentrations in different stages of subclinical atherosclerosis and their relationship with inflammation
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  75. Electrochemical evaluation of the antioxidant capacity of natural compounds on glassy carbon electrode modified with guanine-, polythionine-, and nitrogen-doped graphene
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  78. Polyphenol content and antioxidant activities of Prunus padus L. and Prunus serotina L. leaves: Electrochemical and spectrophotometric approach and their antimicrobial properties
  79. The combined use of GC, PDSC and FT-IR techniques to characterize fat extracted from commercial complete dry pet food for adult cats
  80. MALDI-TOF MS profiling in the discovery and identification of salivary proteomic patterns of temporomandibular joint disorders
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  82. Structure and some physicochemical and functional properties of water treated under ammonia with low-temperature low-pressure glow plasma of low frequency
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  84. Amine-functionalized magnetic activated carbon as an adsorbent for preconcentration and determination of acidic drugs in environmental water samples using HPLC-DAD
  85. Antioxidant activity as a response to cadmium pollution in three durum wheat genotypes differing in salt-tolerance
  86. A promising naphthoquinone [8-hydroxy-2-(2-thienylcarbonyl)naphtho[2,3-b]thiophene-4,9-dione] exerts anti-colorectal cancer activity through ferroptosis and inhibition of MAPK signaling pathway based on RNA sequencing
  87. Synthesis and efficacy of herbicidal ionic liquids with chlorsulfuron as the anion
  88. Effect of isovalent substitution on the crystal structure and properties of two-slab indates BaLa2−xSmxIn2O7
  89. Synthesis, spectral and thermo-kinetics explorations of Schiff-base derived metal complexes
  90. An improved reduction method for phase stability testing in the single-phase region
  91. Comparative analysis of chemical composition of some commercially important fishes with an emphasis on various Malaysian diets
  92. Development of a solventless stir bar sorptive extraction/thermal desorption large volume injection capillary gas chromatographic-mass spectrometric method for ultra-trace determination of pyrethroids pesticides in river and tap water samples
  93. A turbidity sensor development based on NL-PI observers: Experimental application to the control of a Sinaloa’s River Spirulina maxima cultivation
  94. Deep desulfurization of sintering flue gas in iron and steel works based on low-temperature oxidation
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  96. Influence of site-classification approach on geochemical background values
  97. Effects of ageing on the surface characteristics and Cu(ii) adsorption behaviour of rice husk biochar in soil
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  99. Antimicrobial and antifungal activities of bifunctional cooper(ii) complexes with non-steroidal anti-inflammatory drugs, flufenamic, mefenamic and tolfenamic acids and 1,10-phenanthroline
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  101. Screening and analysis of xanthine oxidase inhibitors in jute leaves and their protective effects against hydrogen peroxide-induced oxidative stress in cells
  102. Synthesis and physicochemical studies of a series of mixed-ligand transition metal complexes and their molecular docking investigations against Coronavirus main protease
  103. A study of in vitro metabolism and cytotoxicity of mephedrone and methoxetamine in human and pig liver models using GC/MS and LC/MS analyses
  104. A new phenyl alkyl ester and a new combretin triterpene derivative from Combretum fragrans F. Hoffm (Combretaceae) and antiproliferative activity
  105. Erratum
  106. Erratum to: A one-step incubation ELISA kit for rapid determination of dibutyl phthalate in water, beverage and liquor
  107. Review Articles
  108. Sinoporphyrin sodium, a novel sensitizer for photodynamic and sonodynamic therapy
  109. Natural products isolated from Casimiroa
  110. Plant description, phytochemical constituents and bioactivities of Syzygium genus: A review
  111. Evaluation of elastomeric heat shielding materials as insulators for solid propellant rocket motors: A short review
  112. Special Issue on Applied Biochemistry and Biotechnology 2019
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  114. Study on online soft sensor method of total sugar content in chlorotetracycline fermentation tank
  115. Studies on the Anti-Gouty Arthritis and Anti-hyperuricemia Properties of Astilbin in Animal Models
  116. Effects of organic fertilizer on water use, photosynthetic characteristics, and fruit quality of pear jujube in northern Shaanxi
  117. Characteristics of the root exudate release system of typical plants in plateau lakeside wetland under phosphorus stress conditions
  118. Characterization of soil water by the means of hydrogen and oxygen isotope ratio at dry-wet season under different soil layers in the dry-hot valley of Jinsha River
  119. Composition and diurnal variation of floral scent emission in Rosa rugosa Thunb. and Tulipa gesneriana L.
  120. Preparation of a novel ginkgolide B niosomal composite drug
  121. The degradation, biodegradability and toxicity evaluation of sulfamethazine antibiotics by gamma radiation
  122. Special issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
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  124. Source apportionment of soil contamination based on multivariate receptor and robust geostatistics in a typical rural–urban area, Wuhan city, middle China
  125. Special Issue on 13th JCC 2018
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  127. Preparation of magnetite-silica–cetyltrimethylammonium for phenol removal based on adsolubilization
  128. Topical Issue on Agriculture
  129. Size-dependent growth kinetics of struvite crystals in wastewater with calcium ions
  130. The effect of silica-calcite sedimentary rock contained in the chicken broiler diet on the overall quality of chicken muscles
  131. Physicochemical properties of selected herbicidal products containing nicosulfuron as an active ingredient
  132. Lycopene in tomatoes and tomato products
  133. Fluorescence in the assessment of the share of a key component in the mixing of feed
  134. Sulfur application alleviates chromium stress in maize and wheat
  135. Effectiveness of removal of sulphur compounds from the air after 3 years of biofiltration with a mixture of compost soil, peat, coconut fibre and oak bark
  136. Special Issue on the 4th Green Chemistry 2018
  137. Study and fire test of banana fibre reinforced composites with flame retardance properties
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  139. Disintegration, In vitro Dissolution, and Drug Release Kinetics Profiles of k-Carrageenan-based Nutraceutical Hard-shell Capsules Containing Salicylamide
  140. Synthesis of amorphous aluminosilicate from impure Indonesian kaolin
  141. Special Issue on the International Conf on Science, Applied Science, Teaching and Education 2019
  142. Functionalization of Congo red dye as a light harvester on solar cell
  143. The effect of nitrite food preservatives added to se’i meat on the expression of wild-type p53 protein
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  145. Special Issue on the Joint Science Congress of Materials and Polymers (ISCMP 2019)
  146. Effect of natural boron mineral use on the essential oil ratio and components of Musk Sage (Salvia sclarea L.)
  147. A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent
  148. A study on the bacterial adhesion of Streptococcus mutans in various dental ceramics: In vitro study
  149. Corrosion study of copper in aqueous sulfuric acid solution in the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone: Experimental and theoretical study
  150. Special Issue on Chemistry Today for Tomorrow 2019
  151. Diabetes mellitus type 2: Exploratory data analysis based on clinical reading
  152. Multivariate analysis for the classification of copper–lead and copper–zinc glasses
  153. Special Issue on Advances in Chemistry and Polymers
  154. The spatial and temporal distribution of cationic and anionic radicals in early embryo implantation
  155. Special Issue on 3rd IC3PE 2020
  156. Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications
  157. Special Issue on IC3PE 2018/2019 Conference
  158. Exergy analysis of conventional and hydrothermal liquefaction–esterification processes of microalgae for biodiesel production
  159. Advancing biodiesel production from microalgae Spirulina sp. by a simultaneous extraction–transesterification process using palm oil as a co-solvent of methanol
  160. Topical Issue on Applications of Mathematics in Chemistry
  161. Omega and the related counting polynomials of some chemical structures
  162. M-polynomial and topological indices of zigzag edge coronoid fused by starphene
https://doi.org/10.1515/chem-2020-0027
Keywords for this article
Antiplasmodial; Dryobalanops oblongifolia; Plasmodium falciparum; Stigmastane steroid
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  100. Application of selenium and silicon to alleviate short-term drought stress in French marigold (Tagetes patula L.) as a model plant species
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  102. Synthesis and physicochemical studies of a series of mixed-ligand transition metal complexes and their molecular docking investigations against Coronavirus main protease
  103. A study of in vitro metabolism and cytotoxicity of mephedrone and methoxetamine in human and pig liver models using GC/MS and LC/MS analyses
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  107. Review Articles
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  118. Characterization of soil water by the means of hydrogen and oxygen isotope ratio at dry-wet season under different soil layers in the dry-hot valley of Jinsha River
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  120. Preparation of a novel ginkgolide B niosomal composite drug
  121. The degradation, biodegradability and toxicity evaluation of sulfamethazine antibiotics by gamma radiation
  122. Special issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
  123. Insight into the cadmium and zinc binding potential of humic acids derived from composts by EEM spectra combined with PARAFAC analysis
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  128. Topical Issue on Agriculture
  129. Size-dependent growth kinetics of struvite crystals in wastewater with calcium ions
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  131. Physicochemical properties of selected herbicidal products containing nicosulfuron as an active ingredient
  132. Lycopene in tomatoes and tomato products
  133. Fluorescence in the assessment of the share of a key component in the mixing of feed
  134. Sulfur application alleviates chromium stress in maize and wheat
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  143. The effect of nitrite food preservatives added to se’i meat on the expression of wild-type p53 protein
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  147. A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent
  148. A study on the bacterial adhesion of Streptococcus mutans in various dental ceramics: In vitro study
  149. Corrosion study of copper in aqueous sulfuric acid solution in the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone: Experimental and theoretical study
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  156. Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications
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  159. Advancing biodiesel production from microalgae Spirulina sp. by a simultaneous extraction–transesterification process using palm oil as a co-solvent of methanol
  160. Topical Issue on Applications of Mathematics in Chemistry
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  162. M-polynomial and topological indices of zigzag edge coronoid fused by starphene
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