Home Physical Sciences Bioassay-directed fractionation of a blood coagulation factor Xa inhibitor, betulinic acid from Lycopus lucidus
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Bioassay-directed fractionation of a blood coagulation factor Xa inhibitor, betulinic acid from Lycopus lucidus

  • Yin-Feng Tan , Qiong Wang , Jing-Wen Gong , Xu-Guang Zhang , Yong-Hui Li , Jun-Qing Zhang and You-Bin Li EMAIL logo
Published/Copyright: March 13, 2018

Abstract

Thrombosis is a major cause of morbidity and mortality worldwide and plays a pivotal role in the pathogenesis of several cardiovascular disorders, including acute coronary syndrome, unstable angina, myocardial infarction, sudden cardiac death, peripheral arterial occlusion, ischemic stroke, deep-vein thrombosis, and pulmonary embolism. Anticoagulants, antiplatelet agents, and fibrinolytics can reduce the risks of these clinical events. Especially, the blood coagulation factor Xa (FXa) inhibitor is a proven anticoagulant. Promoting blood circulation, using traditional Chinese medicine (TCM), for the treatment of these diseases has been safely used for thousands of years in clinical practice. Therefore, highly safe and effective anticoagulant ingredients, including FXa inhibitors, could be found in TCM for activating the blood circulation. One FXa inhibitor, a pentacyclic triterpene (compound 1, betulinic acid) characterized by IR, MS and NMR analyses, was isolated from the ethyl acetate fraction of Lycopus lucidus by bioassay-directed fractionation. Compound 1 exhibited an inhibitory effect on FXa with IC50 25.05 μmol/L and reduced the thrombus weight in an animal model at 25-100 mg/kg. These results indicate that betulinic acid could be the potential for anticoagulant therapy.

1 Introduction

Abnormal blood clotting is responsible for several thromboembolic diseases, including myocardial infarction, unstable angina, deep vein thrombosis, pulmonary embolism, and ischemic stroke. Anticoagulants are used for the prevention and treatment of venous and arterial thromboembolic disorders. Vitamin K antagonists (VKAs) have been available for several years. Moreover, until recently, they were the only therapeutic option available as the oral anticoagulation treatment. Direct administration of oral anticoagulants (DOAC) became a critical alternative to VKA for the prevention and treatment of venous thromboembolism (VTE) and the prevention of systemic embolism and ischemic stroke. DOACs are often termed as novel oral anticoagulants or target-specific oral anticoagulants. DOAC and VKA exert different mechanisms of action. VKAs reduce the hepatic synthesis of vitamin K-dependent coagulation factors, such as factor II, VII, IX, and X, whereas DOACs are direct inhibitors of the activated factor II (dabigatran) or activated factor X (Rivaroxaban, Apixaban, Edoxaban) [1]. Factor X has been known to play a pivotal role in hemostasis [2], and FXa is crucial in the blood coagulation pathway acting as a catalyst in the production of thrombin, which leads to clot formation and wound closure [3]. The activity of Factor X can be markedly suppressed without affecting hemostasis, as the existing thrombin is not affected. An ideal anticoagulant would prevent thrombosis without inducing systemic hypocoagulation, thereby avoiding the complications, such as unintended bleeding. Therefore, an FXa inhibitor potentially exhibits the properties of an anticoagulant [4] and has emerged as an attractive target for new anticoagulants.

Traditional Chinese Medicines (TCM) have been used in China for a prolonged period in promoting blood circulation and removing blood stasis. Thus, safe and effective anticoagulant ingredients might be found in TCM. Previously, we found a small, natural and direct inhibitor against FXa from the root of Glycyrrhiza glabra L. [5]. In the present study, we focused on another TCM for removing blood stasis, which was screened out from 18 types of TCM extracts using enzyme-based assay [6]. Lycopus lucidus Turcz.var. hirtus Regel (Lamiaceae, Zelan in Chinese), an herbaceous perennial plant, the aerial part is commonly used for improving blood rheology in clinical practice, as recorded in the chinese famous original herbal classic “ShenNongBenCaoJin” for thousands of years ago [7~9]. Pharmacological research showed that the water decoction of L. lucidus reduced the blood viscosity, fibrinogen content, and hematocrit, shortened the erythrocyte electrophoresis time, and inhibited the erythrocyte and platelet aggregation and thrombosis formation [7~9]. It also resisted coagulation and thrombosis, thereby improving the microcirculation and regulation of metabolism of blood lipids [7,9]. Therefore, to investigate the mechanisms of the plant activity, bioassay-directed fractionation was undertaken using blood coagulation FXa activity in vitro as a reference. This study led to the isolation of a pentacyclic triterpene, betulinic acid, as the active component. Betulinic acid is also found in various plants (Ziziphus jujuba Mill.var. spinosa, Syzygium jambos (L.) Alston, and Betula platyphylla Suk). Its anticoagulant activity has been reported in other study [10], and was verified in our study. Furthermore, our study also revealed that one of the mechanisms of its anticoagulation activity was inhibition of FXa.

2 Materials and methods

2.1 Chemicals and reagents

Purified FXa (HYPHEN BioMed, France, Batch # 090825C-PK:1), chromogenic substrate BIOPHEN CS-11(22) (HYPHEN BioMed, Batch # 93803-1-PK:3), and Rivaroxaban (Bayer AG, Germany, Batch # BXFD8J1) were purchased.

Column chromatography and thin layer silica gel (Qingdao Marine Chemical Factory, China), Sephadex LH-20 gel (Pharmacia Biotech Products, USA), and silica gel GF254 thin layer of prefabricated plates (Yantai chemical industrial Research Institute, China) were utilized.

Petroleum ether, ethyl acetate, normal butanol, methanol, ethanol, chloroform, acetone, and other organic reagents were of analytical grade.

2.2 Plant material

Chinese herbal pieces from aerial part of Lycopus lucidus was purchased from Anhui Hujiao Pharmaceutical Co., Ltd.(batch #20101128). The plant was first identified by a senior research scientist, Shihui Qian of Jiangsu Province Academy of Traditional Chinese Medicine, and voucher specimens deposited in the Chemistry Laboratory of Jiangsu Province Academy of Traditional Chinese Medicine (No.20110614).

2.3 Bioassay-directed extraction and isolation by assessment of the inhibitory effect on FXa in vitro

Pieces of Lycopus lucidus aerial part (5 kg) were extracted three times with 85% ethanol (3×50 L) under reflux for 3 h each time. The extract was evaporated under reduced pressure. The residue (830 g) was suspended in H2O (3 L) and partitioned sequentially with an equivalent volume of ethyl acetate (EtOAc, 118 g) and normal butanol (n-BuOH, 180 g). Subsequently, 1 g of each fraction was solubilized in dimethyl sulfoxide (DMSO) to obtain the concentration of 15 mg/mL for further experiments.

The assay of FXa activity was slightly modified from the previously reported method [11,12]. The reaction system included 20 µL of the phosphate-buffered saline (PBS; pH=8.34, containing 0.3 M NaCl, 0.065 M Na2HPO4, and 0.00167 M KH2PO4), 20 μL of FXa solution (2.5 μg/ mL), 0.2 μL of sample solution (15 mg/mL), and 20 μL of the substrate solution (2.5 mg/mL) was added after preincubating it for 30 mins at 37 °C. DMSO was added to the blank control group instead of the sample solution. The absorbance was measured at 405 nm at an interval of 0.5 min for a total of 5 min after the start of the reaction. The regression curve of the absorbance (OD) was plotted against time (T) using the continuous rate method. The slope of the regression curve represented the average speed of action, the activity of the enzyme, and the effect of the sample on the enzyme as compared to the slope of the blank control group. The inhibitory rate of the sample (I%) was calculated as follows:

I%=(V0Vi)/V0×100%

Where V0 is the slope of the regression curve to the blank control group; Vi is the slope of the regression curve to the sample group.

According to the results of assessment, the EtOAc soluble part (110 g) was further separated by silica gel column chromatography (1000g,100×12cm) eluting with a gradient of CHCl3/MeOH (100:1, 50:1, 25:1, 10:1, 5:1, v/v) to obtain seven fractions ZL1-7. The ZL5 (6.7 g) was subjected to silica gel column chromatography (106g, 40×3cm) eluting with a gradient of petroleum ether /EtOAc (20:1, 15:1, 10:1, 5:1, 3:1, v/v) to obtain five fractions ZL5.1-5.5. The ZL5.3 was subjected to Sephadex LH-20 column chromatography eluting with MeOH/H2O 80:20 to yield the active compound (compound 1, 68.7 mg). These fractions resulted in assay inhibitory effect on FXa. The extraction and isolation process of Lycopus lucidus is shown in Figure 1.

Figure 1 Extraction and isolation process of Lycopus lucidus.
Figure 1

Extraction and isolation process of Lycopus lucidus.

2.4 Assessment of half maximal inhibitory concentration (IC50)

Compound 1 and Rivaroxaban were solubilized in DMSO, respectively, to obtain different concentrations for assessing the inhibitory effect on FXa at each concentration. The conditions of the reaction and the method of assessment were the same as that for the inhibitory effect on FXa in vitro. Consequently, the IC50 was calculated by establishing the regression curve of inhibition rate of the sample vs. the concentration.

2.5 Bleeding time test and inferior vena cava (IVC) thrombosis experiments

The experiments were performed as reported previously [5]. A total of 36 male Sprague–Dawley(SD) rats (220±20 g) were purchased from DongChuang Laboratory Animal Service Department (Changsha, China) and acclimatized for 3 days with free access to food and water. All rats were randomly divided into 6 groups ( n=6) and fasted overnight before dosing; however, free access to water was allowed. For the p.o. administration, betulinic acid was dissolved in a mixture containing 6% PEG400, 9.8% (v/v), and 4.4% (v/v) ethanol. Different groups of rats were orally administered 20, 50, 75, 100 mg/kg betulinic acid and 8.6 mg/kg Rivaroxaban; the control group received blank mixture solvent. After 90 min, the animals were anesthetized with chloral hydrate ( i. p. 350 mg/kg), a 2 mm tail portion was cut and placed in physiological saline, and the bleeding time recorded. After normally bred for 3 days, the drugs were administered orally to the rats. Then, the animals were anesthetized, the abdomen opened, IVC isolated, and two surgical sutures placed under it. Subsequently, thromboplastin (0.5 mg/kg) was injected into the femoral vein, and after 15 s, the IVC was subjected to ligature by surgical sutures (segment length 12mm). 20 min later, the thrombosis in the IVC segment was carefully dissected and weighted after drying in the oven at 60°C.

2.6 Data and statistical analysis

All experiments in vitro were performed at least in triplicate, and the results were expressed as mean±SD. The results of animal experiments expressed as mean±SEM. Statistical analysis was performed using SPSS 17.0 software. P < 0.05 was considered statistically significant.

Ethical approval

All rat experiments were performed in accordance with the Institutional Animal Care and Use Committee at the Hainan Medical University (Haikou, China), as well as the Guidance for Ethical Treatment of Laboratory Animals (The Ministry of Science and Technology of China, 2006).

3 Results

3.1 Effects of extract and fractions on the activities of FXa

The inhibitory effects of Ethanol extract, EtOAc fraction, n-BuOH fraction and Water fraction of L. lucidus on FXa (Table 1). The results showed that the ethanol extract of L. lucidus exerted an inhibitory effect against FXa. Moreover, the EtOAc fraction exhibited a maximal inhibitory effect in the other three extractive fractions. The dose-effect relationship of EtOAc fraction was studied. The inhibitory activity of six different concentrations (1, 3, 6, 12.5, 15, and 25 mg/mL) EtOAc fraction on FXa were as follows: 6.73±4.81%, 46.93±9.92%, 59.01±4.08%, 72.67±3.29%, 74.45±3.48%, and 74.46±2.81% (Figure 2) which increased with increasing concentration. On the other hand, the trend of enhancement declined and saturated at a high concentration, thereby indicating that EtOAc fraction contained direct inhibitors of FXa. The EtOAc fraction was further subjected to column chromatography and obtained fractions ZL1-7, ZL5.1-5.5, compound 1 (betulinic acid). In Table 2, indicated that compound 1 is the active compound to inhibit FXa.

Table 1

Inhibitory effects of different fractions of ethanol extract from Lycopus lucidus on FXa.

FractionConcentration (mg/mL)Inhibition rate (%)
Ethanol extract1592.71±5.92
EtOAc fraction1574.45±3.48
n-BuOH fraction1544.54±4.58
Water fraction1534.57±2.73

Inhibition rate was expressed as mean±SD, n=5. The positive control was Rivaroxaban with the inhibition rate of 99.16% at the concentration of 50 μg/mL.

Table 2

Inhibitory effects of different fractions from EtOAc fraction on FXa.

FractionConcentration (mg/mL)Inhibition rate (%)
ZL11517.03±2.11
ZL21510.10±1.09
ZL31552.08±5.22
ZL41550.10±4.19
ZL51586.12±2.99
ZL61551.48±1.01
ZL71536.44±1.25
ZL5.11522.19±1.54
ZL5.21550.78±2.31
ZL5.31589.92±4.62
ZL5.41556.98±4.31
ZL5.51540.23±2.57
Compound 11585.89±4.10

Inhibition rate was expressed as mean±SD, n=3. The positive control was Rivaroxaban with the inhibition rate of 99.16% at the concentration of 50 μg/mL.

Figure 2 Inhibition curves of different concentrations of EtOAc fraction to FXa.
Figure 2

Inhibition curves of different concentrations of EtOAc fraction to FXa.

3.2 Identification of the structure of the purified compound

The compound 1 (betulinic acid) was obtained as white crystals. UV (MeOH) λmax: 206.8nm. Optical rotation: [α] D+8°. The IR spectrum showed absorption bands for OH (3441 cm-1), associated hydroxyl (2500-3080cm-1), and COOH (1710–1735 cm-1) groups. ESI-MS m/z: 457 [M+H]+. 1H-NMR (DMSO-d6, 300 MHz) δ ppm: 4.68 (1H, s, 29-H), 4.56 (1H, s, 29-H), 1.64 (3H, brs, 30-H), 0.65, 0.76, 0.87, 0.93 (15H, s, Me×5). 13C-NMR (DMSO-d6, 75 MHz) δppm: 37.5 (C-1), 27.1 (C-2), 76.7 (C-3), 38.2 (C-4), 54.8 (C-5), 18.9 (C-6), 33.9 (C-7), 38.7 (C-8), 49.9 (C-9), 36.7 (C-10), 20.4 (C-11), 25.0 (C-12), 38.4 (C-13), 42.0 (C-14), 29.1 (C-15), 31.7 (C-16), 55.4 (C-17), 48.5 (C-18), 46.6 (C-19), 150.3 (C-20), 30.1 (C-21), 36.3 (C-22), 28.0 (C-23), 15.7 (C-24), 15.7 (C-25), 15.9 (C-26), 14.3 (C-27), 177.9 (C-28), 109.5 (C-29), 17.9 (C-30). The detailed analysis NMR and MS data and comparison with the reference data [13,14] indicated that the compound was betulinic acid. The chemical structure of the compound 1 is shown in Figure 3.

Figure 3 Chemical structure of betulinic acid (compound 1) isolated from Lycopus lucidus.
Figure 3

Chemical structure of betulinic acid (compound 1) isolated from Lycopus lucidus.

3.3 Effects of betulinic acid on the activities of FXa

The inhibitory effect of betulinic acid on FXa was measured at the concentration of 15 mg/mL in DMSO. The inhibitory activity was 85.89±4.95% (n=5, P < 0.01). Thus, betulinic acid is a direct inhibitor of blood FXa. The IC50 of betulinic acid against FXa was measured in the presence of rivaroxaban as a positive control (Table 3). The IC50 of betulinic acid and Rivaroxaban were found to be 25.05 μmol/L and 1.04×10-2 μmol/L, respectively.

Table 3

IC50 of betulinic acid on FXa.

CompoundConcentration (mg/mL)Final Concentration (μmol/L)Inhibition rate (%)IC50 (μmol/L)
Betulinic acid (1)17.2912.52±5.6625.05
2.518.2138.51±7.73
536.4365.59±4.10
1072.8686.98±2.72
15109.2885.89±4.95
20145.7192.52±3.04
Rivaroxaban5× 10-43.8×10-324.90±6.861.04x10-2
1× 10-37.6× 10-342.30±9.43
2× 10-315.2× 10-356.91±4.04
3× 10-322.7× 10-373.58±7.91
4× 10-330.5× 10-376.10±9.29
5× 10-338.1× 10-381.00±6.54

Inhibition rate was expressed as mean±]SD, n=5.

3.4 Effects of betulinic acid on the bleeding time and thrombosis of IVC

Bleeding in rats was induced by tail trisection. The thrombus model was prepared by intravenous injection of thromboplastin (0.5 mg/kg) and ligation of the IVC. As shown in Figure 4A, betulinic acid did not have a significant influence on bleeding time at a concentration of 25–100 mg/kg. As shown in Figure 4B, betulinic acid can significantly reduce the weight of thrombosis at 25–100 mg/kg.

Figure 4 Effects of betulinic acid on bleeding time (A) and thrombosis of IVC (B).Values are mean±SEM ( n=6), compared with control group ** P< 0.01, # P< 0.05.
Figure 4

Effects of betulinic acid on bleeding time (A) and thrombosis of IVC (B).Values are mean±SEM ( n=6), compared with control group ** P< 0.01, # P< 0.05.

4 Discussion

We found that betulinic acid has direct inhibitory effect on FXa, this discovery which may partially revealed to be material basis and mechanism of anticoagulant activity of L. lucidus. Although the inhibitory effect of betulinic acid was significantly weaker than control compound rivaroxaban, it’s inhibitory effect was similar comparing with oxazolidinones (IC50=20μmol/L), the lead compound of rivaroxaban [15]. This indicated, possible development of more potent compounds from natural product betulinic acid by chemical structural modification. Various biological properties of betulinic acid have been reported in other studies, including anti-tumor anti-inflammatory, and antiviral effects [16,17]. In the present study, we found that betulinic acid inhibited FXa in vitro directly and reduced the thrombus weight in an animal model; however, the bleeding times were not significantly affected. These characteristics indicated that betulinic acid might be used as a relatively safe anticoagulant with favorable efficacy/bleeding ratio. We, also previously, reported that glycyrrhetinic acid directly inhibited FXa [5]. Together, these studies indicated the presence of natural inhibitors of FXa in medicinal plants. These results proved that medicinal plants contain anticoagulant ingredients. However, when using anticoagulants clinically, patients should not use these plants at the same time to avoid the risk of bleeding.

Acknowledgments

The study was financially supported by The National Natural Science Foundation of China (grant number 81460591).

  1. Conflict of interest

    Conflict of interests: The authors declare no conflict of interest.

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Abbreviations

FXa

blood coagulation factor Xa

VKA

vitamin K antagonists

DOAC

direct oral anticoagulants

VTE

venous thromboembolism

EtOAc

ethyl acetate

n-BuOH

normal butanol

DMSO

dimethyl sulfoxide

IVC

inferior vena cava

Received: 2017-11-06
Accepted: 2018-01-13
Published Online: 2018-03-13

© 2018 Yin-Feng Tan et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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  55. Efficient optimization and mineralization of UV absorbers: A comparative investigation with Fenton and UV/H2O2
  56. Metabolites of Tryptophane and Phenylalanine as Markers of Small Bowel Ischemia-Reperfusion Injury
  57. Adsorption and determination of polycyclic aromatic hydrocarbons in water through the aggregation of graphene oxide
  58. The role of NR2C2 in the prolactinomas
  59. Chromium removal from industrial wastewater using Phyllostachys pubescens biomass loaded Cu-S nanospheres
  60. Hydrotalcite Anchored Ruthenium Catalyst for CO2 Hydrogenation Reaction
  61. Preparation of Calcium Fluoride using Phosphogypsum by Orthogonal Experiment
  62. The mechanism of antibacterial activity of corylifolinin against three clinical bacteria from Psoralen corylifolia L
  63. 2-formyl-3,6-bis(hydroxymethyl)phenyl benzoate in Electrochemical Dry Cell
  64. Electro-photocatalytic degradation of amoxicillin using calcium titanate
  65. Effect of Malus halliana Koehne Polysaccharides on Functional Constipation
  66. Structural Properties and Nonlinear Optical Responses of Halogenated Compounds: A DFT Investigation on Molecular Modelling
  67. DMFDMA catalyzed synthesis of 2-((Dimethylamino)methylene)-3,4-dihydro-9-arylacridin-1(2H)-ones and their derivatives: in-vitro antifungal, antibacterial and antioxidant evaluations
  68. Production of Methanol as a Fuel Energy from CO2 Present in Polluted Seawater - A Photocatalytic Outlook
  69. Study of different extraction methods on finger print and fatty acid of raw beef fat using fourier transform infrared and gas chromatography-mass spectrometry
  70. Determination of trace fluoroquinolones in water solutions and in medicinal preparations by conventional and synchronous fluorescence spectrometry
  71. Extraction and determination of flavonoids in Carthamus tinctorius
  72. Therapeutic Application of Zinc and Vanadium Complexes against Diabetes Mellitus a Coronary Disease: A review
  73. Study of calcined eggshell as potential catalyst for biodiesel formation using used cooking oil
  74. Manganese oxalates - structure-based Insights
  75. Topological Indices of H-Naphtalenic Nanosheet
  76. Long-Term Dissolution of Glass Fibers in Water Described by Dissolving Cylinder Zero-Order Kinetic Model: Mass Loss and Radius Reduction
  77. Topological study of the para-line graphs of certain pentacene via topological indices
  78. A brief insight into the prediction of water vapor transmissibility in highly impermeable hybrid nanocomposites based on bromobutyl/epichlorohydrin rubber blends
  79. Comparative sulfite assay by voltammetry using Pt electrodes, photometry and titrimetry: Application to cider, vinegar and sugar analysis
  80. MicroRNA delivery mediated by PEGylated polyethylenimine for prostate cancer therapy
  81. Reversible Fluorescent Turn-on Sensors for Fe3+ based on a Receptor Composed of Tri-oxygen Atoms of Amide Groups in Water
  82. Sonocatalytic degradation of methyl orange in aqueous solution using Fe-doped TiO2 nanoparticles under mechanical agitation
  83. Hydrotalcite Anchored Ruthenium Catalyst for CO2 Hydrogenation Reaction
  84. Production and Analysis of Recycled Ammonium Perrhenate from CMSX-4 superalloys
  85. Topical Issue on Agriculture
  86. New phosphorus biofertilizers from renewable raw materials in the aspect of cadmium and lead contents in soil and plants
  87. Survey of content of cadmium, calcium, chromium, copper, iron, lead, magnesium, manganese, mercury, sodium and zinc in chamomile and green tea leaves by electrothermal or flame atomizer atomic absorption spectrometry
  88. Biogas digestate – benefits and risks for soil fertility and crop quality – an evaluation of grain maize response
  89. A numerical analysis of heat transfer in a cross-current heat exchanger with controlled and newly designed air flows
  90. Freshwater green macroalgae as a biosorbent of Cr(III) ions
  91. The main influencing factors of soil mechanical characteristics of the gravity erosion environment in the dry-hot valley of Jinsha river
  92. Free amino acids in Viola tricolor in relation to different habitat conditions
  93. The influence of filler amount on selected properties of new experimental resin dental composite
  94. Effect of poultry wastewater irrigation on nitrogen, phosphorus and carbon contents in farmland soil
  95. Response of spring wheat to NPK and S fertilization. The content and uptake of macronutrients and the value of ionic ratios
  96. The Effect of Macroalgal Extracts and Near Infrared Radiation on Germination of Soybean Seedlings: Preliminary Research Results
  97. Content of Zn, Cd and Pb in purple moor-grass in soils heavily contaminated with heavy metals around a zinc and lead ore tailing landfill
  98. Topical Issue on Research for Natural Bioactive Products
  99. Synthesis of (±)-3,4-dimethoxybenzyl-4-methyloctanoate as a novel internal standard for capsinoid determination by HPLC-ESI-MS/MS(QTOF)
  100. Repellent activity of monoterpenoid esters with neurotransmitter amino acids against yellow fever mosquito, Aedes aegypti
  101. Effect of Flammulina velutipes (golden needle mushroom, eno-kitake) polysaccharides on constipation
  102. Bioassay-directed fractionation of a blood coagulation factor Xa inhibitor, betulinic acid from Lycopus lucidus
  103. Antifungal and repellent activities of the essential oils from three aromatic herbs from western Himalaya
  104. Chemical composition and microbiological evaluation of essential oil from Hyssopus officinalis L. with white and pink flowers
  105. Bioassay-guided isolation and identification of Aedes aegypti larvicidal and biting deterrent compounds from Veratrum lobelianum
  106. α-Terpineol, a natural monoterpene: A review of its biological properties
  107. Utility of essential oils for development of host-based lures for Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae), vector of laurel wilt
  108. Phenolic composition and antioxidant potential of different organs of Kazakh Crataegus almaatensis Pojark: A comparison with the European Crataegus oxyacantha L. flowers
  109. Isolation of eudesmane type sesquiterpene ketone from Prangos heyniae H.Duman & M.F.Watson essential oil and mosquitocidal activity of the essential oils
  110. Comparative analysis of the polyphenols profiles and the antioxidant and cytotoxicity properties of various blue honeysuckle varieties
  111. Special Issue on ICCESEN 2017
  112. Modelling world energy security data from multinomial distribution by generalized linear model under different cumulative link functions
  113. Pine Cone and Boron Compounds Effect as Reinforcement on Mechanical and Flammability Properties of Polyester Composites
  114. Artificial Neural Network Modelling for Prediction of SNR Effected by Probe Properties on Ultrasonic Inspection of Austenitic Stainless Steel Weldments
  115. Calculation and 3D analyses of ERR in the band crack front contained in a rectangular plate made of multilayered material
  116. Improvement of fuel properties of biodiesel with bioadditive ethyl levulinate
  117. Properties of AlSi9Cu3 metal matrix micro and nano composites produced via stir casting
  118. Investigation of Antibacterial Properties of Ag Doped TiO2 Nanofibers Prepared by Electrospinning Process
  119. Modeling of Total Phenolic contents in Various Tea samples by Experimental Design Methods
  120. Nickel doping effect on the structural and optical properties of indium sulfide thin films by SILAR
  121. The effect mechanism of Ginnalin A as a homeopathic agent on various cancer cell lines
  122. Excitation functions of proton induced reactions of some radioisotopes used in medicine
  123. Oxide ionic conductivity and microstructures of Pr and Sm co-doped CeO2-based systems
  124. Rapid Synthesis of Metallic Reinforced in Situ Intermetallic Composites in Ti-Al-Nb System via Resistive Sintering
  125. Oxidation Behavior of NiCr/YSZ Thermal Barrier Coatings (TBCs)
  126. Clustering Analysis of Normal Strength Concretes Produced with Different Aggregate Types
  127. Magnetic Nano-Sized Solid Acid Catalyst Bearing Sulfonic Acid Groups for Biodiesel Synthesis
  128. The biological activities of Arabis alpina L. subsp. brevifolia (DC.) Cullen against food pathogens
  129. Humidity properties of Schiff base polymers
  130. Free Vibration Analysis of Fiber Metal Laminated Straight Beam
  131. Comparative study of in vitro antioxidant, acetylcholinesterase and butyrylcholinesterase activity of alfalfa (Medicago sativa L.) collected during different growth stages
  132. Isothermal Oxidation Behavior of Gadolinium Zirconate (Gd2Zr2O7) Thermal Barrier Coatings (TBCs) produced by Electron Beam Physical Vapor Deposition (EB-PVD) technique
  133. Optimization of Adsorption Parameters for Ultra-Fine Calcite Using a Box-Behnken Experimental Design
  134. The Microstructural Investigation of Vermiculite-Infiltrated Electron Beam Physical Vapor Deposition Thermal Barrier Coatings
  135. Modelling Porosity Permeability of Ceramic Tiles using Fuzzy Taguchi Method
  136. Experimental and theoretical study of a novel naphthoquinone Schiff base
  137. Physicochemical properties of heat treated sille stone for ceramic industry
  138. Sand Dune Characterization for Preparing Metallurgical Grade Silicon
  139. Catalytic Applications of Large Pore Sulfonic Acid-Functionalized SBA-15 Mesoporous Silica for Esterification
  140. One-photon Absorption Characterizations, Dipole Polarizabilities and Second Hyperpolarizabilities of Chlorophyll a and Crocin
  141. The Optical and Crystallite Characterization of Bilayer TiO2 Films Coated on Different ITO layers
  142. Topical Issue on Bond Activation
  143. Metal-mediated reactions towards the synthesis of a novel deaminolysed bisurea, dicarbamolyamine
  144. The structure of ortho-(trifluoromethyl)phenol in comparison to its homologues – A combined experimental and theoretical study
  145. Heterogeneous catalysis with encapsulated haem and other synthetic porphyrins: Harnessing the power of porphyrins for oxidation reactions
  146. Recent Advances on Mechanistic Studies on C–H Activation Catalyzed by Base Metals
  147. Reactions of the organoplatinum complex [Pt(cod) (neoSi)Cl] (neoSi = trimethylsilylmethyl) with the non-coordinating anions SbF6– and BPh4
  148. Erratum
  149. Investigation on Two Compounds of O, O’-dithiophosphate Derivatives as Corrosion Inhibitors for Q235 Steel in Hydrochloric Acid Solution
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