PRELIMINARY PHYTOCHEMICAL SCREENING AND EVALUATION OF ANTIBACTERIAL ACTIVITY OF DIFFERENT SOLVENT EXTRACTS OF PLECTRANTHUS BOURNEAE GAMBLE (LAMIACEAE)

Objective: The aim was to investigate the antibacterial activity of Plectranthus bourneae Gamble (Lamiaceae) using different solvents.Methods: Petroleum ether, chloroform, acetone, ethanol and aqueous leaves extracts at different concentration (25, 50, 75, 100 μg/ml) wereevaluated for antibacterial activity using disc diffusion method against some Gram-positive species namely Bacillus subtilis, Clostridium sporogenes,Staphylococcus aureus, Streptococcus mutans, Streptococcus mitis and Gram-negative species Salmonella typhi, Klebsilla pneumoniae, Entrobactoraerogenes, Citrobactor freundii, Escherichia coli. The minimum inhibitory concentration (MIC) and minimum bacterial concentrations (MBC) weredetermined by serial dilution method.Results: The antibacterial activity results of ethanol extract (50 μg/ml) showed maximum zone of inhibition (26 mm) against S. aureus and MICvalue of 0.78 μg/ml and MBC of 1.56 μg/ml whereas aqueous extract was least effective on all the strains. The Gram-positive strains of S. aureus andS. mutans were found to be the most sensitive and resistance on all the extracts. Except S. typhi, Gram-negative bacteria used were less inhibitoryeffect to all the extracts.Conclusion: The present study concluded that the ethanolic extracts of P. bourneae possess potential antibacterial activities against certainmicroorganisms.Keywords: Plectranthus bourneae, Antibacterial activity, Disc diffusion method, Lamiaceae