Diterpenes and Phenolic Compounds from Salvia brachyodon Vandas

Salvia brachyodon, the short-tooth sage, is one of the rarest plant species and endemic in the Adriatic area of the Balkan Peninsula. As aside from its essential oil, only limited information on its phytochemical composition is known, a more detailed study of the leaves was undertaken. From its leaves two diterpenes, agastanol (2), and a new natural compound 1, i.e., 3-methyl-4-methylen-11,12,14-trihydroxy-8,11,13-abietatrien-7-one, were isolated and identified by NMR spectroscopy and mass spectrometry. In addition, caffeic acid, isoquercitrin, luteolin 7-O-glucoside and rosmarinic acid were identfied by comparison with reference compounds. The fraction containg the diterpenes as well as the isolated compound 1 showed significant antimycobacterial activity against Mycobacterium smegmatis. The diterpenes of S. brachyodon represent promising antimycobacterial substances for further evaluation. Due to the endangered nature of the plant, the wide use of S. brachyodon and its bioactive compounds could be achieved by growing the plants in culture.