Novel flavonol-3-O-methylethers from Zanthoxylum pistaciifolium Griseb. (Rutaceae)

Zanthoxylum pistaciifolium Griseb. is a tree endemic to Cuba, occasionally used in herbal medicine. Previously, the antitrypanosomal activity of a n-hexane-2-butanone extract of Z. pistaciifolium leaves and of its constituent skimmianine were published. In the current study a more thorough examination of the respective extract is performed, which led to the isolation and identification of three flavonoids, more specifically, the flavonol-3-O-methylethers kaempferol-3-O-methylether (1) and novel compounds kaempferol-3-O-methylether-5-O-β-D-glucoside (2) and kaempferol-8-hydroxy-3,7-O-dimethylether-5-O-β-D-glucoside (3). All compounds were screened for their antimicrobial and antiprotozoal activity and cytotoxicity towards MRC-5 SV2 cells. Compound 1 showed a moderate to weak activity against Trypanosoma cruzi (IC₅₀ 30.8 μM), T. brucei (IC₅₀ 15.4 μM) and Plasmodium falciparum (IC₅₀ 53.8 μM), but also showed cytotoxicity (CC₅₀ 19.0 μM). Compounds 2 and 3 did not display activity in any of the assays (IC₅₀ and CC₅₀ > 64 μM).[Formula: see text].