ANTIBACTERIAL EFFECTS OF VERNONIA AMYGDALINA AND OCIMUM GRATISSIMUM EXTRACTS ON GRAM-NEGATIVE CLINICAL ISOLATES

ABSTRACT Increase in antimicrobial resistance coupled with successful treatment of various diseases with herbal medications has triggered the upsurge in research geared towards harnessing the medicinal potentials of various plants. This study investigated the antibacterial activity of ethanolic, ethyl acetate, and water extracts of V. amygdalina and O. gratissimum, against some clinical isolates (Salmonella typhi, Pseudomonas sp and Escherichia coli) using agar diffusion method to determine the antibacterial effects of both plant extract on the test organisms. Phytochemical analysis of O. gratissimum (Scent leaf) and V. amygdalina (bitter leaf) revealed that it contains bioactive compounds which include: tannins, saponins, flavonoid, alkaloids, steroid and phenol. The zone of inhibition of the plant extract diameters at concentration of 100mg/ml ranged from 25 to 9 mm for water, ethyl acetate and ethanol extract respectively on the test organisms. The synergistic activity of ethyl acetate and ethanol extract showed higher activity compared to water extract. The minimum inhibitory concentrations (MIC) of water, ethyl acetate and ethanol extracts on the test organisms ranged from 25 mg/ml – 50 mg/ml. The (MIC) of water extract of O. gratissimum on the test organisms ranged from 12.5 mg/ml – 50 mg/ml. The MIC of all extract for V. amygdalina ranged from 3.125 mg/ml to 50 mg/ml. The findings underpin the need for more medicinal plants as sources of antibacterial drugs to combat problems associated with antibacterial drugs resistance.