Antiparasitic activity of some xanthones and biflavonoids from the root bark of Garcinia livingstonei

A new biflavanoid, ent-naringeninyl-(I-3α,II-8)-4′-O-methylnaringenin (6), along with five known xanthones and two known biflavonoids, was isolated from the root bark of Garcinia livingstonei collected in Tanzania. The absolute configuration of 6 was established by CD spectroscopy. This compound showed moderate activity against P. falciparum (IC50 6.7 μM). Antitrypanosomal activity (IC50 0.87 μM) was observed for 1,4,5-trihydroxy-3-(3-methylbut-2-enyl)-9H-xanthen-9-one (3). The dimeric xanthone garcilivin A (4) showed a higher and nonselective antiparasitic activity and cytotoxicity (IC50 2.0 μM against MRC-5 cells) than its diastereoisomer garcilivin C (5) (IC50 52.3 μM). © 2006 American Chemical Society and American Society of Pharmacognosy.