The Influence Of Selected Antimalarial Herbal Products On CYP Activity

Seven medicinal plants popularly used in West Africa in combination with prescription antimalarial drugs, were selected for an herb-drug interaction study. They were found to inhibit the conversion of artesunate (an antimalarial drug) to its active metabolite dihydroartemisinin in liver microsomes, a reaction catalyzed by CYP2A6, CYP2B6 and CYP3A6 [1]. In the current study, the inhibitory effects of the methanolic extracts of these plants on the activity of seven CYP isoforms (CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) were assessed using the recombinant CYP test kits. The assay conditions were as reported earlier [2]. Significant inhibition of various CYPs was observed with IC₅₀ values < 5 µg/mL by Annona aff. Muricata (CYP2C9, 3A4 and CYP2D6), Mangifera indica (CYP2C9), Momordica charantia (CYP2C19 and CYP2C19), Phyllanthus amarus (CYP2C19, CYP2C9 and CYP3A4) and Tithonia diversifolia (CYP2C19 and CYP3A4). These findings suggest that coadministration of the herbal products with the conventional drugs could elicit herb-drug interactions through CYP inhibition and also provide plausible mechanism for the observed inhibition of artesunate metabolism to dihydroartemisinin.

Acknowledgements: Study supported by USAID grant for Africa-U.S. Higher Education Partnership program, USAID/HED Grant No HED 153 – 6200-BFA-15 – 01

References: 1. Fasinu PS, Avula B, et al. (2015). 81(05), PB26. 2. Manda VK, Avula B, et al. (2013). Planta Med. 79 1421 – 1428