Ganoboninketals A-C, Antiplasmodial 3,4-seco-27-Norlanostane Triterpenes from Ganoderma boninense Pat.

Three new nortriterpenes, ganoboninketals A-C (1-3), featuring rearranged 3,4-seco-27-norlanostane skeletons and highly complex polycyclic systems were isolated from the medicinal mushroom Ganoderma boninense. The structures of the new metabolites were established by spectroscopic methods. The absolute configurations in 1-3 were assigned by electronic circular dichroism (ECD) calculations. Compounds 1-3 showed antiplasmodial activity against Plasmodium falciparum with IC50 values of 4.0, 7.9, and 1.7 mu M, respectively. Compounds 1 and 3 also displayed weak cytotoxicity against A549 cell line with IC50 values of 47.6 and 35.8 mu M, respectively. Compound 2 showed weak cytotoxicity toward HeLa cell line with an IC50 value of 65.5 mu M. Compounds 1-3 also presented NO inhibitory activity in the LPS-induced macrophages with IC50 values of 98.3, 24.3, and 60.9 mu M, respectively.