Antiplasmodial compounds from Urera gravenreuthii (Urticaceae), their structure-activity relationship and chemotaxonomic significance

Abstract

The liana Urera gravenreuthii Engl. is an endemic plant to Cameroon which was not yet been chemically and pharmacologically investigated so far despite its uses for medical purposes in local folk medicine to treat several illnesses including dysentery, neuralgia and malaria. This study mainly aimed to contribute to providing further information on the chemical composition of the plant and to identify its antiplasmodial compounds which might support its effectiveness against malaria. The purification of the methanolic extract of U. gravenreuthii led to the isolation and characterization of fifteen distinct compounds (1‒15) which were structurally confirmed using their NMR data. Thirteen compounds (1‒11, 14‒15) were evaluated for their antiplasmodial activity against P. falciparum 3D7 and the results showed that the most active were betulinic acid (2) (2.2 ± 0.2 μM), rutin (9) (2.8 ± 1.4 μM), quercetin (8) (3.7 ± 1.3 μM) and lupeol (1) (4.8 ± 0.3 μM) which displayed a good activity with IC50 < 5 μM. Furthermore, the hypotheses on the structure-activity relationship of the tested compounds and the chemotaxonomic significance of the study have been discussed. The results support the identification of the plant as a member of the family Urticaceae, strengthen its use for the management of malaria and qualify it as an important source of good candidates in new antiplasmodial drug development.