Lophachinins A-E, abietane diterpenes from a Mongolian traditional herbal medicine Lophanthus chinensis.

Five new abietane diterpenes, lophachinins A-E (1-5), and eleven known related diterpenes were isolated from a Mongolian traditional herbal medicine, the aerial parts of Lophanthus chinensis (Lamiaceae). The structures of new diterpenes were assigned by spectroscopic analyses. Lophachinins A (1) and B (2) were abietane diterpene possessing an endoperoxy bridge at C-ring. In contrast, lophachinins C-E (3-5) had an abietane skeleton with an aromatized C-ring. The absolute configuration of 1 was elucidated by application of the modified Mosher's method, while those of 2, 3, and 5 were assigned by chemical conversions. The absolute configuration of lophachinin D (4) was deduced by ECD calculation. Anti-inflammatory activity of isolated diterpenes on microglial cells were evaluated.