A New Abietane Diterpenoid from Plectranthus bishopianus Benth.

Chemical examination of the MeOH extract of Plectranthus bishopianus Benth., a rare and endangered plant, resulted in isolation of a new abietane diterpene, 6 β-hydroxy-7 α-methoxyroyleanone ( 1), along with two more diterpenoids, 6,7-dehydroroyleanone, and 6 β,7 α-dihydroxyroyleanone, a triterpene oleanolic acid, and two sterols, β-sistosterol and stigmasterol. The structures of the isolated compounds were elucidated on the basis of spectroscopic data and also by comparison with authentic samples. [ABSTRACT FROM AUTHOR]