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 beta-hydroxy-7a-methoxyroyleanone (1), along with two more diterpenoids, 6,7-dehydroroyleanone, and 6 beta,7a-dihydroxyroyleanone, a triterpene oleanolic acid, and two sterols, beta-sistosterol and stigmasterol. The structures of the isolated compounds were elucidated on the basis of spectroscopic data and also by comparison with authentic samples.