Antiprotozoal Activities of Heterocyclic-Substituted Xanthones from the Marine-Derived Fungus Chaetomium sp.
journal contributionposted on 26.09.2008, 00:00 by Alexander Pontius, Anja Krick, Stefan Kehraus, Reto Brun, Gabriele M. König
Investigations of the marine-derived fungus Chaetomium sp. led to the isolation of the new natural products chaetoxanthones A, B, and C (1−3). Compounds 1 and 2 are substituted with a dioxane/tetrahydropyran moiety rarely found in natural products. Compound 3 was identified as a chlorinated xanthone substituted with a tetrahydropyran ring. The configurational analysis of these compounds employed CD spectroscopy, modified Mosher’s method, and selective NOE gradient measurements. Compound 2 showed selective activity against Plasmodium falciparum with an IC50 value of 0.5 μg/mL without being cytotoxic toward cultured eukaryotic cells. Compound 3 displayed a moderate activity against Trypanosoma cruzi with an IC50 value of 1.5 μg/mL.