The antimicrobial,antioxidative, anti-inflammatory activity and cytotoxicity of different fractions of four South African Bauhinia species used traditionally to treat diarrhoea |
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| Authors: | Aroke S. Ahmed Esameldin E. Elgorashi Nivan Moodley Lyndy J. McGaw Vinasan Naidoo Jacobus N. Eloff |
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| Affiliation: | 1. Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa;2. Biosciences, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa;3. Biomedical Research Centre, University of Pretoria, South Africa |
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| Abstract: | Ethnopharmacological importanceMany Bauhinia species, including those indigenous to South Africa, are used in traditional medicine across the world for treating ailments such as gastrointestinal tract (GIT) disorders, diabetes, infectious diseases and inflammation.AimsSeveral relevant aspects of different fractions of leaf extracts of Bauhinia bowkeri (BAB), Bauhinia galpinii (BAG), Bauhinia petersiana (BAP), and Bauhinia variegata (BAV) used in South African traditional medicine to alleviate diarrhoea related symptoms were evaluated.Materials and MethodsThe antioxidative activities of the extracts were determined using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS+) radical scavenging and ferric reducing antioxidant power (FRAP) methods. In vitro antimicrobial activities of the extracts were determined against bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis) and clinical isolates of the opportunistic fungal strains (Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans) using a serial dilution microplate method. The polyphenolic contents were quantified using standard methods, and anti-inflammatory activities of the crude extracts were determined using the cyclooxygenase and soybean 15-lipoxygenase enzyme inhibitory assays. The safety of the extracts was evaluated by determining the cytotoxicity against Vero cell lines.ResultsThe acidified 70% acetone crude extract and their fractions had good antiradical potency against the DPPH and ABTS radicals. The methanol soluble portions of the butanol fractions were more potent (EC50 ranges from 0.64±0.05 to 1.51±0.07 and 0.88±0.18 to 1.49±0.09 μg/ml against DPPH and ABTS radical respectively) compared to the standard, trolox and ascorbic acid (EC50 ranges from 1.47±0.24 to 1.70±0.27 μg/ml) for both DPPH and ABTS. The crude extracts contained variable quantities of phenolic content. The crude extracts and their fractions had weak to good antimicrobial activities, inhibiting the growth of the organisms at concentrations ranging from 39 to 2500 μg/ml. The BAG crude extract and its fractions were the most active against the fungi (MICs ranging from 39 to 625 μg/ml) while the BAB extract and its fractions were the least active with the MICs ranging between 39 and 2500 μg/ml. Aspergillus fumigatus was the least susceptible fungus while Cryptococcus neoformans was the most susceptible.The phenolic-rich crude extracts of BAB, BAG, and BAP had moderate to good dose-dependent cyclooxygenase-1 enzyme inhibitory activity with inhibitions between 22.8% and 71.4%. The extracts were however, inactive against cyclooxygenase-2. The extracts had some level of cytotoxicity towards Vero cell lines, reducing cell viability to less than 10% at concentrations more than 50 μg/ml.ConclusionThe biological activities observed in Bauhinia species provide a scientific basis for the use of the plants in traditional medicines to treat diseases with multi-factorial pathogenesis such as diarrhoea, with each aspect of activity contributing to the ultimate therapeutic benefit of the plants. However, the use of the phenolic-rich extracts of these plants to treat diarrhoea or any other ailments in traditional medicine needs to be monitored closely because of potential toxic effects and selective inhibition of COX-1 with the associated GIT injury. |
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| Keywords: | A, absorbance A02, Absorbance at time 0 min Ab2, absorbance of blank ABTS+=2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid radical AlCl3, aluminium chloride ANOVA, analysis of variance ARM, antibiotic resistant microbe At2, absorbance at time T ATCC, American Type Culture Collection BAB, Bauhinia bowkeri BAG, Bauhinia galpinii BAP, Bauhinia petersiana BAV, Bauhinia variegata BuOH, butanol CE, catechin equivalent CH3COONa, Sodium ethyl acetate CO2, Carbon dioxide COX, cyclooxygenase= Cyn-3-glu, cyanidin-3-glucoside DCM, dichloromethane DNA, deoxyribose nucleic acid DF, dilution factor DMSO, dimethyl sulphoxide DPM, disintegration min-1 DPPH, 2, 2-diphenyl-1-picrylhydrazyl EC50, effective concentration required to inhibit scavenge free radicals by 50% ETOAc, ethyl acetate FLL, flavonol FRAP, ferric reducing antioxidant power GAE, gallic acid equivalent GIT, gastrointestinal tract GT, gallotannin HCl, hydrochloric acid IBD, irritable bowel disease IC50, concentration required to reduce cyclooxygenase by 50% INT, iodonitrotetrazolium violet K2Fe3(CN6), potassium ferrocyanide K2S2O4, potassium persulphate K3Fe3(CN6), potassium ferricyanide LC50, dose of extract necessary to induce cytotoxic effect by 50% LE, leucoproanthocyanidin equivalent LOX, lipoxygenase LPO, lipid peroxidation MEM, minimal essential medium mg, milligram MIC, minimum inhibitory concentration= MTT, 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyl tetrazolium bromide NaHCO3, Sodium hydrogen carbonate NCCLS, National Committee for Clinical Laboratory Standards NRF, National Research Fund OH, hydroxyl ORT, oral rehydration therapy PBS, phosphate buffer solution PG, prostaglandin PVPP, polyvinylpolypyrrolidone QE, quercetin equivalent RNS, reactive nitrogen species ROS, reactive oxygen species SDS, sodium dodecyl sulphate solution SE, standard error TEAC, Trolox equivalent antioxidant capacity TLC, thin layer chromatography TF, total flavonoid TP, total phenolic |
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