In vitro antileishmanial and antimalarial activity of selected plants of Nepal

BACKGROUND Nepal is very rich in biodiversity, and no extensive effort has yet been carried out to screen plants that are used by traditional healers against parasitic diseases. The aim of this study was to evaluate the in vitro antileishmanial and antimalarial activity of crude methanolic or ethanolic extracts of 29 plant species that are currently used by local people of Nepal for treating different ailments. METHODS Crude extracts of leaves, twigs, aerial parts, and/or roots of the selected plants were evaluated for in vitro inhibitory activity against intracellular amastigotes of Leishmania infantum and against erythrocytic stages of Plasmodium falciparum. To determine the selectivity index (SI), cytotoxicity was assessed on MRC-5 cells in parallel. RESULTS Three plant species, namely Phragmites vallatoria and Ampelocissus tomentosa, for which no antiprotozoal activity has previously been reported, and Terminalia chebula revealed antiprotozoal activity. The extract of A. tomentosa exhibited moderate activity against L. infantum with an inhibitory concentration 50% (IC50) of 13.2 ± 4.3 µg/ml and SI >3, while T. chebula exhibited fairly good antiplasmodial activity with IC50 values of 4.5 ± 2.4 µg/ml and SI values >5. CONCLUSION In countries like Nepal, where the current health system is unable to combat the burden of endemic parasitic diseases, evaluation of local plants as a potential source of the drug can help in expanding the treatment options. The extent of untapped resources available in these countries provides an opportunity for future bioprospecting.