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

摘要

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 tri-terpenoids 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. (C) 2020 Elsevier Ltd. All rights reserved.