PHYTOCHEMICAL ANALYSIS AND ANTIBACTERIAL ACTIVITIES OF OCIMUM GRATISSIMUM LEAVES

Abstract

The phytochemical analysis and antibacterial activities of Ocimum gratissimum leaf extracts were carried out in the month of July, 2012. The phytochemical screening of Ocimum gratissimum leaves revealed the presence of steroids, saponins, alkaloids in the aqueous extract while flavonoids, alkaloids, cardiac glycosides and tannins were found in the ethanolic extract. The bacterial strains used in this study were pure clinical isolates of Staphylococcus aureus and Escherichia coli obtained from the Microbiology Laboratory, University of Abuja Teaching Hospital, Abuja. The isolates were tested for viability by sub-culture into nutrient broth at 37⁰C and kept in the incubator for 24 hours prior to antibacterial testing. The antibacterial activities of the plant extracts were tested on the test isolates using Agar-well diffusion techniques. The MIC (Minimum Inhibitory Concentration) of the potent extracts was determined according to the macro broth dilution technique. The Minimum Bactericidal Concentration (MBC) was also carried out. Escherichia coli and Staphylococcus aureus showed inhibition zones ranging from 11.0 to 20.0mm. From this study, it was observed that ethanol extracts exhibited high inhibitory activity on Escherichia coli; a representative of enteric coliforms and Gram negative bacteria and Staphylococcus aureus; a representative of Gram positive bacteria than the aqueous extract. This can be deduced to the ability of ethanol to extract more of the essential oils and secondary plant metabolites which are believed to exert antibacterial activity on the test organisms. This study however can justify the use of the leaves in traditional medicine practice as a therapeutic agent for the maintenance of health and can explain the long use of this plant. Further experimental research efforts on the plant and its extracts are needed to be able to ascertain the safety of the plant.