Antibacterial Potential of Ethanolic and Aqueous Extracts of Carica papaya Leaves

Abstract

Background: The search for newer sources of antibiotics is a global challenge pre-occupying research institutions, pharmaceutical companies and academia, since many infectious agents are becoming resistant to synthetic drugs. Aim: This present study sought to investigate the antibacterial potential of ethanolic and aqueous extracts of Carica papaya leaves. Materials and Methods: Fresh and healthy leaves of C. papaya were harvested, air dried and milled into powder. The powder was extracted using ethanol and water as solvents. The antibacterial activities of both extracts were determined by diffusion method. Nutrient agar medium was prepared using standard method. Pure cultures of Coliform bacillus, Staphylococcus epidermidis, Streptococcus viridans, Salmonella typhi and Escherichia coli were obtained from the Department of Veterinary Microbiology and Parasitology, Federal University of Agriculture, Abeokuta, Nigeria. The extracts were serially diluted to obtain 1.0%, 0.5%, 0.25% and 0.125% solutions in sterile test tubes. Sterilized 9 mm filter paper disc soaked in the diluted extracts were placed on the plate and incubated for 24 hours at room temperature. The plates were examined for clear zones of inhibition. Presence of zones of inhibition indicated activity. Results: the results showed that both ethanolic and aqueous extracts of C. papaya leaves exhibit antibacterial activities against C. bacillus, S. epidemidis, S. viridans and E. coli and also inhibited their growth. The effect of the ethanolic extract was greater than that of the aqueous extract. However, this activity was not observed with S. typhi. Conclusion: The result of the present study showed that C. papaya leaves might effectively inhibit the growth of C. bacillus, S. epidemidis, S. viridans and E. coli but not that of S. typhi. However, the ethanolic extract is more potent than the aqueous extract.