University of Khartoum

Polyphenol Profile and Biological Activities of Salvadora persica L. Stem and Leaf

Polyphenol Profile and Biological Activities of Salvadora persica L. Stem and Leaf

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Title: Polyphenol Profile and Biological Activities of Salvadora persica L. Stem and Leaf
Author: Abd El Aziz, Hana Abd El Aziz Eltieb
Abstract: Salvadora persica L (Arak or Miswak tree) of the family Salvadoraceae is used in Sudan and Greeko-Arab systems of traditional medicine to treat several diseases. Miswak, a chewing stick is prepared from its stings, is also used traditionaly as antimicrobial toothbrush for oral hygiene. The aim of this study was to investigate the polyphenol profile and in vitro antimicrobial, antimycetomal, antimalarial, antioxidant, cytotoxic and acetyl cholinesterase (AChE) and glycogen phosphorylase (Gp) inhibitory activities of S. persica stem and leaf. Dried powdered leaf and stem were subjected separately to maceration with 70% methanol. The concentrated methanolic extract was sequentially fractionated with petroleum ether, chloroform and ethyl acetate. Dried extracts and fractions were then dissolved in 1% DMSO (dimethyl sulfoxide) for different biological assays. Antimicrobial activity was determined against Gram positive (Staphylococcus aureus and Streptococcus feacalies) and Gram negative (Escherichia coli and Pseudomonas aeruginosa) bacteria as well as the fungi Candida albicans using the disc diffusion method and Madurella mycetomatis. Minimum inhibitory concentration (MIC) was determined by microdilution method. Antimalarial activity was determined by the microplate assay against the K1 parasite strain of Plasmodium falciparum. Cytotoxicity was determined against the brine shrimp (Artemia salina). The antioxidant activity was evaluated by scavenging activity of the stable 1, 1-diphenyl-2-picryl hydrazyl (DPPH) free radical. Phytochemical study was performed by using different chromatographic techniques including Thin Layer Chromatography (TLC), High Performance Liquid Chromatography (HPLC) and Reverse phase HPLC-DAD coupled with Tandem mass spectrometry techniques. Acetyl cholinesterase and glycogen phosphorylase inhibitory activity were determined by in silico docking approach using Surflex software. Results showed that crude methanolic extracts of both the stem and leaf displayed very weak antibacterial and antifungal activities. However, fractionation of the crude extracts improved the antimicrobial activity especially against S. feacalies, P. aeruginosa and C.albicans. Chloroform fractions from both the stem and leaf showed high sensitivity towards S. feacalies and P. aeruginosa with MIC values of 0.156 and 0.25 mg/ml respectively. Leaf petroleum ether, leaf and stem chloroform and stem ethyl acetate fractions displayed the same MIC value (1.25 mg/ml) against C. albicans. Stem crude methanolic extract presenting best activity against M. mycetomatis with MIC value of 0.156 mg/ml. Fractionation of crude methanolic extracts of both organs increased its antiplasmodial potential where the highest antiplasmodial activity was obtained from the stem chloroform fraction (IC50 79.3 µg/ml). Ethyl acetate fractions of the stem and leaf displayed remarkable DPPH scavenging activity with IC50 23.87 and 21.64 µg/ml respectively. Crude methanolic extract of the stem was not toxic. Seven polyphenolic compounds which were reported for the first time in this study; Kaempferol- 7-0- β-hexose-deoxyhexoside (1) and Quercetin-7-α-O-rhamnoside-(1-6'')-β-O gluopyranoside (2) (identified in both stem and leaf), Isorhamnetin 7-0-hexose- deoxyhexoside (3), Kaempferol-4'-O- deoxyhexose-7-0-β hexoside (4), Isorhamnetin 7-0- β-glucopyranoside (5) and Quercetin-7-0- β-glucopyranoside (6) (identified in the stem) and Kaempferol - 7-0- β-glucopyranoside (7) (identified in the leaf) were identified from the ethyl acetate fractions of both organs. In silico study showed that compounds 7 and 6 have good AChE binding affinity while all identified compounds (1-7) showed high binding affinity towards at least one specific binding site of Gp enzyme through hydrogen and - bonds. In conclusion leaf and stem of S. persica could be potential source of polyphenols with interesting in vitro biological activity which could further be applied in in vivo studies for the elucidation of their possible mechanism(s) of action. In silico study suggested that S. persica could be a promising potential source against diabetes and Alzheimer’s disease.
URI: http://khartoumspace.uofk.edu/123456789/27072


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