Fernene Triterpenoids from the Lichen Pyxine berteriana

Abstract

Two new fernene triterpenoids, fern-9(11)-en-3,19-dione (1) and 3beta-acetoxyfern-9(11)-en-19-one (2), together with the known 3beta-acetoxyfern-9(11)-en-19beta-ol (3) and lichexanthone (4), have been isolated from the acetone extract of the lichen Pyxine berteriana. The structures of the new compounds were established on the basis of IR, extensive 1D and 2D NMR, and MS analyses. Although several fern-9(11)-enes have been isolated from lichens, compounds 1 and 2 are the first examples of naturally occurring fernene triterpenoids with a carbonyl function at C-19.