ANTIBACTERIAL ACTIVITY OF PSIDIUM GUAJAVA L. LEAVES EXTRACTS AGAINST SOME GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA

Gitika and Manoj Kumar*

ABSTRACT

Antibacterial efficiency of Psidium guajava L. leaves extracts in different solvents (methanol, ethanol and aqueous) were studied against seven different bacterial strains, including four gram-positive (Micrococcus luteus, Bacillus subtilis, Staphylococcus aureus and Streptococcus sp.) and three gram-negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium) using agar well diffusion assay (AWDA) method. In the present study, aqueous extract gave the highest yield percentage as compared to methanol as well as ethanol extracts. The patterns of inhibition varied with the solvent as well as the tested microorganisms. The results showed that M. luteus among the gram-positive and E. coli among the gram-negative were highly susceptible as compared to other tested organisms. The methanol extract of P. guajava was the most effective as the widest inhibitory zone was observed as compared to the ethanol and aqueous extracts. The minimum inhibitory concentrations (MIC) as well as the minimum bactericidal concentration (MBC) of the crude leaves extracts were determined for the various organisms which ranged between 12.5 to 100 mg/ml. The remarkable antibacterial activity of the leaves extracts against tested gram-positive and gram-negative bacteria suggests that the P. guajava plant leaves could be a possible source of novel broad spectrum drug for treating infectious diseases.

Keywords: Antibacterial; Psidium guajava; Solvents; Zone of Inhibition.