Evaluation of the in vitro antiplasmodial, antileishmanial and antitrypanosomal activities of selected medicinal plants from the Arabian Peninsula

Abstract

Today over one billion people worldwide are at risk for tropical diseases caused by parasitic organisms. The World Health Organization (WHO) now classifies many as neglected tropical diseases, having an enormous impact on socioeconomic development and quality of life at all levels particularly in developing countries. Malaria, leishmaniasis and human African trypanosomiasis are still major public health problems in need for new and more effective drugs. The aim of this study was to exploit traditional healer knowledge and evaluate in vitro antiprotozoal activity of twenty-five medicinal plants collected from Saudi Arabia and the island Soqotra. The plants were extracted with methanol and screened for their in vitro antiprotozoal activity against erythrocytic schizonts of Plasmodium falciparum, intracellular amastigotes of Leishmania infantum and Trypanosoma cruzi and axenic T. brucei trypomastigotes. To assess selectivity, cytotoxic activity was determined against MRC-5 cells. Criteria for activity were an IC50 < 10 µg/ml. Selective activity was obtained for Chrozophora oblongifolia (Del.) A. Juss. ex Spreng., Dracaena cinnabari Balf. f., Ficus ingens (Miq.), Hypoestes pubescens Balf. f., Lavandula dentata L., Plectranthus barbatus Andr. and Punica protopunica Balf. f. against P. falciparum (IC50 2 – 8 µg/mL) while Dracaena cinnabari, Euriendra balfourii Cogn. & Balf. f., Grewia erythraea L. and Vernonia leopoldii Vatke displayed activity against the three kinetoplastid parasites (IC50 < 10 µg/mL). Acridocarpus socotranus Oliv. was moderately active against T. brucei (IC50 3.5 µg/mL). Ballochia atrovirgata Balf. f., Dendrosicycos socotrana Balf. f., Dracaena cinnabari and Euphorbia socotrana Balf. f. displayed non-specific inhibition of the parasites related to high cytotoxicity.