Antibacterial Activity of Crude Momordica charantia, Cassia alata, and Allium sativum Methanolic Extracts on Leptospira interrogans serovar Manilae.

Background and objective: Leptospirosis is a disease caused by pathogenic Leptospira prevalent in tropical countries like the Philippines. Some studies have shown that the role of currently used antibiotics for leptospirosis is unclear since trials have found no significant benefit to patient outcomes compared to placebo. This signals the need for alternative therapies, such as herbal medicines, which may provide effective therapeutic regimens in treating this infection. In this study, we characterized the antibacterial potential of three Philippine herbal medicines against Leptospira interrogans.

Methods: Crude methanolic extracts of Momordica charantia, Cassia alata, and Allium sativum were subjected to an optimized broth microdilution assay against L. interrogans, utilizing the resazurin-resorufin reaction as a cell proliferation and viability indicator.

Results: The respective minimum inhibitory concentrations of the plants were found to be as follows: 1.25 mg/mL (M. charantia), 2.5 mg/mL (C. alata), and >5 mg/mL (A. sativum).

Conclusions: Among the three herbal medicines, M. charantia and C. alata proved to have antibacterial activity against L. interrogans. Given the promising potential of two of these plant extracts, exploring the use of other solvents to extract natural compounds from these plants, and discovering possible synergistic effects between these plants and conventional antibiotics may be worthwhile.