Neo-clerodane diterpenes from Salvia herbacea.

Chemical investigation of the aerial parts of Salvia herbacea led to the isolation of eight new neo-clerodane diterpenes (1-8), named tehuanins A-H, and three known compounds. The structures of these compounds were determined by analysis of their spectroscopic data. Three of the new diterpenes possess a 1,8-epoxy group (1-3). This unusual structural feature was confirmed by X-ray diffraction of 1. The structure of the previously isolated 1α,10α-epoxysalviarin was revised. The absolute configuration of 6 was established by X-ray diffraction analysis of its bromo derivative 6a. Cytotoxic and anti-inflammatory activities of these diterpenes were examined. None of the compounds were considered to be cytotoxic; however, compound 7 exhibited anti-inflammatory activity comparable to that of indomethacin.