Antimalarial benzoquinones from an endophytic fungus, Xylaria sp.

Two novel benzoquinone metabolites, 2-chloro-5-methoxy-3-methylcyclohexa-2,5-diene- 1,4-dione (1) and xylariaquinone A (2) together with two known compounds were isolated from an endophytic fungus, Xylaria sp. Their structures were assigned by analysis of spectroscopic data, and the structures of I and 3 were also confirmed by single-crystal X-ray data. Compounds I and 2 showed in vitro activity against Plasmodium falciparum, K1 strain, with IC50 values of 1.84 and 6.68 mu M and cytotoxicity against African green monkey kidney fibroblasts (Vero cells) with IC50 values of 1.35 and > 184 mu M, respectively.