Applanhydrides A and B, lanostane triterpenoids with unprecedented seven-membered cyclo-anhydride in ring C from Ganoderma applanatum

Abstract

Two novel lanostane triterpenoids with an unprecedented seven-membered cyclo-anhydride moiety in ring C, named applanhydrides A ( 1 ) and B ( 2 ), and two new lanostane triterpenoids with a 1,2-diketone moiety in ring C, named applandiketones A ( 3 ) and B ( 4 ), were isolated from the fruiting bodies of Ganoderma applanatum . The structures of the compounds were determined by extensive NMR spectroscopic analyses and theoretical calculations. Compounds 1 and 2 represent the first cases of triterpenoids featuring a seven-membered cyclo-anhydride moiety in ring C. Co-existing of triterpenoids with anhydride and 1,2-diketone moiety in ring C indicated an enzymatic Baeyer-Villiger oxidation process might occur in the ring C, which is not discovered before. Anti-inflammatory assay revealed that compound 4 showed significant inhibitory activity against NO production in LPS-induced RAW 264.7 cells. • Two novel lanostane triterpenoids were isolated from the fruiting bodies of Ganoderma applanatum. • Two new lanostane triterpenoids with 1,2-diketone moiety in ring C were isolated from Ganoderma applanatum. • One of the compounds showed potent inhibitory effects on NO production in LPS-induced RAW264.7 cells.