Neoclerodane diterpenoids from Teucrium montbretii subsp. libanoticum and their absolute configuration.

From the aerial parts of Teucrium montbretii subsp. libanoticum 10 neoclerodane diterpenoids were isolated. Three of them are new [3beta-hydroxyteubutilin A (1), 12-epi-montanin G (2), 20-epi-3,20-di-O-deacetylteupyreinidin (3)], whereas the other seven, namely, 6-ketoteuscordin (4), teuscordinon (5), 6beta-hydroxyteuscordin (6), montanin D (7), 3,20-di-O-deacetylteupyreinidin (8), montanin G (9), and 3-O-deacetylteugracilin A (10), are previously known structures. The structures of 1-3 were determined by spectral and chemical methods.