Three new lanostanoid triterpenes from the fruiting bodies of Ganoderma tropicum.

Three new lanostanoid triterpenes, 3β,7β,15β-trihydroxy-11,23-dioxo-lanost-8,16-dien-26-oic acid (1), 3β,7β,15β-trihydroxy-11,23-dioxo-lanost-8,16-dien-26-oic acid methyl ester (2), and 3β,15β-dihydroxy-7,11,23-trioxo-lanost-8,16-dien-26-oic acid methyl ester (3) were isolated from the EtOAc extract of the fruiting bodies of Ganoderma tropicum. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopy as well as MS. The bioassay of inhibitory activity against acetylcholinesterase (AChE) of these isolates was evaluated and compound 2 exhibited definite inhibitory activity against AChE.