Philippine tsaang gubat (Ehretia microphylla Lam) and ampalaya (Momordica charantia L.) leaf extracts lack amoebicidal activity in vitro

ABSTRACT

Background@#Amoebiasis is a global health problem affecting poor regions in the world. Few drugs such as metronidazole are available to treat this disease; unfortunately, it is associated with several serious side effects. Tsaang gubat and ampalaya have been used by traditional healers from different cultures to treat dysentery.@*Objective@#The aim of this research was to provide evidence to validate the use of tsaang gubat and ampalaya leaf extracts for dysentery by determining their anti-amoebic activity.@*Methods@#The tsaang gubat and ampalaya leaves were sourced from the University of the Philippines at Los Baños and processed into a lyophilized aqueous extract. Anti-amoebic activity was determined in an in vitro assay using Entamoeba histolytica HK-9 strain against 10 dose levels (18-10,000 μg/mL). The amoeba and leaf extracts were incubated for 24, 48, and 72 hours. The trophozoites were stained with Trypan blue and dispensed into chambers of a Neubauer hemocytometer. The live trophozoites (unstained) were counted under a binocular microscope. The MIC and IC50 were determined. Metronidazole and DMSO served as positive and negative controls, respectively.@*Results@#Tsaang gubat and ampalaya leaves failed to show anti-amoebic activity and even had increased growth of amoeba at all dose levels. The IC50 of tsaang gubat and ampalaya leaf extracts were >500 μg/mL at 24, 48, and 72 hours. Metronidazole was able to eradicate the amoeba parasite at 24 and 72 hours, while exposure to DMSO did not result in inhibition nor death of the parasite.@*Conclusion@#Tsaang gubat and ampalaya aqueous leaf extracts did not exhibit any anti-amoeba activity.