Labdane Diterpenoids from Marrubium globosum ssp. libanoticum.

From the aerial parts of Marrubium globosum ssp. libanoticum, seven labdane diterpenoids were isolated. Three of them are new natural products [(13R)-9alpha,13alpha-epoxylabda-6beta(19),16(15)-diol dilactone (2), deacetylvitexilactone (7), marrulanic acid (8)], whereas the other four, namely, (13S)-9alpha,13alpha-epoxylabda-6beta(19),16(15)-diol dilactone (1), cyllenin A (3), 15-epi-cyllenin A (4), and marrulibanoside, are previously known compounds. The structures of 2, 7, and 8 were determined by spectroscopic and chemical methods.