Evaluation of in vitro antiprotozoal and cytotoxic activities of selected medicinal plants used in nigerian folk medicine

Abstract

The global burdens of trypanosomiasis, malaria and leishmaniasis have continued to impoverish the developing countries. These protozoan parasitic diseases are still endemic in sub-Saharan Africa; and drug resistance and toxicities have further aggravated this situation. The aim of the study is to validate some folkloric claims on the uses of the selected plants in ethnomedicine in Nigeria. The study selected eight plants based on their use in the management of parasitic protozoan diseases and evaluated their antiprotozoal as well as cytotoxic activities. The methanol extracts of the plants were tested for in-vitro activities against Trypanosoma brucei rhodesiense (Tbr), Trypanosoma cruzi (Tcr), Leishmania donovani (Ldon) and Plasmodium falciparium as well as mammalian skeletal L6 myoblast for cytotoxicity. The results showed moderate to low in-vitro antiprotozoal and cytotoxic activities. Aspilia africana (IC50 8.15 μg/mL) and Caesalpinia pulcherrima (IC50, 3.98 μg/mL) showed significant in-vitro anti-Tbr activity with selectivity indices of 6 and 9.7 respectively. C. pulcherrima (IC50: 12.14 μg/mL, Ldon; 14.0, Pfc), Dissotis rontundifolia (IC50: 18.45 μg/mL, Tbr), Ficus glumosa flower (IC50: 16.05 μg/mL, Tbr), Morinda morindiodes (IC50: 13.46 μg/mL, Tbr), Senna alata (IC50: 10.51 μg/mL, Tbr; 18.07 μg/mL, Ldon) and Sphenocentrum jollyannum (IC50: 11.53 μgmL, Tbr; 18.30 μg/mL, Ldon; 13.26 μg/mL, Pfc) showed moderate activities. Further separation of C. pulcherrima extract resulted in improved antileishmanial (IC50, SI: 4.57 μg/mL, 4.6) and antiplasmodial (IC50, SI: 3.80 μg/mL, 5.6) activities. This study has shown that some plants used in folk medicine in Nigeria could be potential sources of lead compounds for parasitic infection.