ABSTRACT

 Antibacterial activity, Minimum lnhibitory Concentration (MIC) and Minimum Bacteriocidal concentration (MBC) of methanolic and aqueous extracts from leaves of Piliostigma thonningii, stem bark of Dacryodes edulis, and whole plant of Euphorbia hirta were studied. The clinical isolates were Escherichia coli, Staphylococcus aureus, Pseudomoras aeruginosa, Salmonella enterica type Typhi 'and the type cultures were Staphylococcus aureus subsp. Aureus (ATCC® 259237), Escherichia coli (ATCC® 25922T), Pseudomonas aeruginosa (ATCC® 27853™) and Enterococcus faecalis (A TCC® 7080™). Quantitative phytochemical screening of the test plant parts was also carried out and they were observed to contain Alkaloid, Saponin, Flavonoid, Tannin and Phenol which are likely to be responsible for the antibacterial activity of the plants. The mean diameter of zone of inhibition produced by the varying concentration of the plant parts against the test organisms ranged from 6mm to I 0mm with MIC and MBC values ranging from 500 to> I 000(µg/ml). The leaf extracts of P.thonningii had antimicrobial activity against S.aureus, S. enterica type Typhi, E. coli (ATCC® 2592279 and P. aeruginosa (ATCC® 278537') with mean diameter zone of inhibition that ranged from 6mm to 8mm. Stem bark extracts of D. edulis had antimicrobial activity against all the test organisms with mean diameter zone of inhibition that ranged from 6mm to I 0mm except against P. aeruginosa (A TCC® 27853™). Whole plant extracts of E. hirta had antimicrobial activity against all the test organisms. The methanolic extracts from plant parts of P. thonningii, D. edu/is, and E. hirta had antibacterial activity on 37.5%, 87.5% and I 00% of the test organisms respectively, while the aqueous extracts from plant parts of P. thonningii, D. edulis, and E. hirta had antibacterial activity on 25%, 50% and 37.5% of the test organisms respectively. The results of the antimicrobial activities showed that the methanol extracts have more inhibitory effects against the test organisms compared to the water extract of the plant parts, this suggests that the bioactive compounds arc more in the methanol extracts. The antimicrobial activities of these extracts provide justification for the use of these medicinal' plants in the traditional treatment of certain diseases and infections caused by the test organisms and thus further studies towards medicinal potential of these plants should be carried out.