Antibacterial property of leaf ethanol extracts of Persea americana Mill. variants against Staphylococcus aureus

Abstract

Background: Antibacterial resistance poses a significant health and economic burden worldwide. Relatedly, plant-based drug discovery remains an important adjunct to modern pharmaceutical research and development. Plants have an extensive record of being used as a form of alternative healthcare. For instance, the leaves of Persea americana Mill. (avocado) were used by traditional medicinal healers in Africa and the Philippines to alleviate common ailments such as skin ulcers and diarrhea.

Objectives: To determine their antibacterial activity, leaves of different P. americana variants maintained at the National Plant Genetic Resources Laboratory, University of the Philippines Los Baños were subjected to disk diffusion assay.

Methodology: Four P. americana leaf ethanol extracts (Cardinal, Morado, Semil 1, and Semil 2 variants) were tested in a range of concentrations (5 mg to 5 μg) against S. aureus (ATCC 25923) and E. coli (ATCC 25922) using standard disc diffusion.

Results: At 5 mg, all four P. americana leaf variants exhibited an inhibitory activity against S. aureus. Furthermore, Semil 2 variant showed the strongest relative antibacterial potential with activity at lower concentrations of 1.25 mg and 0.31 mg. On the other hand, all four variants did not suppress E. coli growth at the concentrations used.

Conclusion: The results indicate the potential antibacterial activity of P. americana leaf variants against S. aureus which is consistent with their ethnomedicinal use as a skin ulcer treatment since S. aureusis a common etiologic agent of skin ulcers. Furthermore, the findings suggest the four P. americana leaf variants, particularly Semil 2, as possible sources of novel antibacterial compounds against S. aureus.