Diterpenes from the aerial part of Salvia columbariae

Abstract The new diterpenes 11,12-di- O -methylrosmanol and 11,12-di- O -methylcarnosol, together with the known compounds carnosic acid, carnosol, rosmanol, epirosmanol, isorosmanol, salvicanol and rosmadial were isolated from the aerial part of Salvia columbariae . The structures of the new diterpenes were established from their spectral data and by chemical correlations. The co-occurence of all these compounds in a single species provides further support of our previously postulated biogenetic pathway to highly oxidized abietatriene compounds involving enzymatic dehydrogenation processes and the participation of singlet oxygen.