Tetra-,penta-,and hexa-nor-lanostane triterpenes from the medicinal fungus Ganoderma australe

Chemical investigation on the medicinal fungus Ganoderma australe led to the identification of ten new nor-lanostane triterpenes,namely two hexa-nor ones,ganoaustratetraenones A(1)and B(2),five penta-nor ones,ganoaustraldehydes A-E(3-7),and three tetra-nor ones ganoaustrenoic acids A-C(8-10).The chemical structures along with the absolute configurations were determined by extensive spectroscopic analysis of 1D&2D NMR and HRESIMS data.The postulated biosynthesis pathways of these compounds were proposed.Ganoaustraldehydes A(3)and B(4)showed moderate inhibition against nitric oxide production in RAW264.7 macrophage cells with the respec-tive IC_(50) values of 32.5,34.2μM(the IC_(50) of positive control pyrrolidine dithiocarbamate was 20.0μM).