[20(22)<i>E</i>]-Lanostane Triterpenes from the Fungus <i>Ganoderma australe</i>

Abstract

Twelve new lanostane triterpenoids (1–5, 7–13) were isolated from the fruiting bodies of the fungus Ganoderma australe. The structures of the new compounds were elucidated by extensive 1D and 2D NMR, and HRESIMS spectroscopic analysis. All the triterpenes are featured by 20(22)E configurations which are uncommon in the Ganoderma triterpene family. The absolute configuration of the C-25 of compounds 1, 2, and 6 were determined by the phenylglycine methyl ester (PGME) method. A postulated biosynthetic pathway for compound 1 was discussed. This study opens new insights into the secondary metabolites of the chemically underinvestigated fungus G. australe.

Keywords

• <i>Ganoderma australe</i>
• triterpene
• 20(22)<i>E</i> configuration
• PGME method