Obtusinones D and E, linear and angular fused dimeric icetexane diterpenoids from Premna obtusifolia roots

Abstract Two new dimeric icetexane diterpenoids, obtusinones D and E ( 1 and 2 ), were isolated from the root extracts of Premna obtusifolia . Obtusinone D ( 1 ) represents the first example of a novel linear fused dimeric icetexane, whereas obtusinone E ( 2 ) is an angular fused icetexane. The structures of 1 and 2 were elucidated on the basis of 1D and 2D NMR spectral data analysis.