Abstract:
Bacterial diseases are several causes for mortality and morbidity in all regions of the world due to the resistance of antibiotics. Plants have been used as a primary source of medicine in the traditional healthcare systems around the world due to the presence of bioactive secondary metabolites. The aim of this research work was to investigate phytochemical constituents and evaluate antimicrobial activity on the stem bark extracts of Vernonia biafrae. The dried and powdered steam bark of the plant material was extracted with four types of solvents (petroleum, chloroform, acetone and methanol) respectively. The chloroform extract was subjected to column chromatography for further purification and isolation of the bioactive compounds. The first fraction 2% ethyl acetate in petroleum ether yields compound 1(1-tricosanol), the second fraction 7% ethyl acetate in petroleum ether yields compound 2 (stigmasterol). TLC was used for monitoring the isolation techniques. The structural elucidation of isolated compounds was done based on data gathered from 1 H-NMR and 13C-NMR spectroscopic techniques. Antimicrobial activities of the crude extracts and isolated compounds were carried out on four bacterial strains (B. subtilus, S. aureus, E. coli and S.typhi) and two of fungal strains (Candida and Fuzarium). The antimicrobial analysis showed that the acetone extract was the most active followed by petroleum ether, chloroform and methanol extracts. Acetone extract showed the greatest activity in both Gram positive and Gram negative bacteria. It has high potential against s. typhi, E. coli, and S. aureus by showing inhibition zone of 7.1, 7.3, and 7.9 mm respectively. Petroleum ether extract showed greater inhibition zone against E. coli, s.typhe and S. Aureus by showing inhibition zone of 7, 7.2 and 7 mm respectively. Compound 2 showed active antimicrobial activity than compound 1
