Antileishmania and Immunostimulating Activities of Two Dimeric Proanthocyanidins From Khaya senegalensis

Abstract

Bioassay-guided fractionation of the bark of Khaya senegalensis (Desr.) A. Jus. (Meliaceae) led to the isolation of two dimeric proanthocyanidins, catechin-(4a,6)-catechin (1) and catechin-(4a,8)-catechin) (2), with immunostimulating activities. Their structures were determined by chromatographic and spectroscopic methods (HREIMS, EIMS, 1 H-NMR). Anti- Leishmania screening of extracts and pure compounds was conducted against Leishmania donovani, L. major, L. infantum promastigotes and retested against L. donovani amastigotes persisting in RAW macrophages as host cells. Their cytotoxicity was evaluated against three mammalian cell lines (RAW, A549 and KB). Isolated compounds (1) and (2) were not active against promastigotes (EC 50 > 25.0 µg/ml), but exhibited significant effects when tested against amastigotes indicating an indirect immunostimulating principle (EC 50 = 3.85 and 3.98 µg/mL, respectively) with no cytotoxicity.