ABSTRACT

The emergence of antibiotic resistance as well as the recent undesirable side effect of some of the commercially available antibiotics has led to the screening of plant extract in order to discover new drug that could serve as alternative therapy for the treatment of various infections and diseases. Fresh leaf of Ocimum gratissimum (scent leaf), Gonronema latifoliun(utazi)and Vernonia amydalina (bitter leaf) were collected  air-dried at room temperature and blended to powder using electric blender. The extraction was done using reflux extraction method using ethanol and water  as solvent. The antibacterial activities of the test plants were determined to ascertain the different phytochemicals present in the plant extract. The extract was also tested against some selected Gram negative and Gram positive intestinal pathogenic bacteria; Escherichia coli, Salmonella species,Staphylococcus aureus and Enterococci faecalis  by reconstituting the extract  to obtain different concentration (100,50 and 25 g/ml) and agar well diffusion techniques were used to evaluate the antibacterial susceptibility of the leaf extract. The result of antibacterial analysis showed that the extract of O. gratissimum and V. amydalina has antibacterial activity against E. coli and Salmonella while the extract of G.latifolium has anti microbial activity against S.aureus and E.faecalis. This could be as a result of the presence of various phytochemicals or the interaction of one or more of the identified metabolites against the test organisms. The results obtained from this research, suggest that Escherichia coli and salmonalla was susceptible to the leaf extract of  O.gratissimum and V.amydalina while S.aureus and E.faecalis is susceptible to G.latifolium. Generally the ethanolic extracts of the plant materials shows a higher antibacterial activity than the aqueous extracts.