Antiplasmodial Activity of Leaf Extracts of Zanthoxylum chalybeum Engl.

Background: Medicinal herbs have long been used in the treatment of malaria in the endemic tropical and subtropical regions of the world, especially in sub-Saharan Africa where malaria has remained as a top killer disease to children under five years and expectant mothers. Among the herbs commonly used in Uganda to treat malaria is Zanthoxylum chalybeum (ZC) root-bark and to a lesser extent its leaves. However, the continued use of the root-bark has led to plant extinction due to the destructive method of harvesting the herb as opposed to the leaves.
Aim: The study investigated the antiplasmodial activity of the crude ether and methanol leaf extracts of ZC with chloroquine diphosphate as a positive control.
Materials and Methods: The in vitro Micro-Test (MARK III) kit was used to determine the antiplasmodial activity of Z. chalybeum Engl. ether and methanol extracts. The effective concentration that caused a 50% P. falciparum schizonts suppression (EC50) values were determined. The antiplasmodial activities of the ether and methanol extracts were expressed as 50% effective concentration (EC50) that was determined from dose-response curve by non-linear regression analysis (curve-fit) using GraphPad Prism (version 6) software at 95% confidence intervals.
Results: The results showed that ether extract of ZC had EC50 value of 13.39 (95% CI: 10.82 – 16.59) µg/ml and methanol extract had EC50 value of 8.10 (95% CI: 5.89 – 11.12) µg/ml. The chloroquine diphosphate, standard had EC50 value of 25.33 (95% CI: 17.07 – 37.60) µg/ml.
Conclusion: The ether and methanol extracts of Z. chalybeum Engl. contains compounds that caused Plasmodium falciparum schizonts suppression at a lower concentration, hence the continued use of the herb by the traditional herbalist and local communities in Uganda, in the treatment of malaria.