Antibacterial diterpenes from the roots of Salvia blepharochlaena

The roots of Salvia blepharochlaena have yielded two new diterpenoids, blephaein (1) and O-methylpisiferic acid methyl ester (2), together with eight known diterpenoids. The structures of the new compounds were established by spectroscopic analysis and by some chemical reactions. Potent antibacterial activity was exhibited by the known compounds horminone (9) and 7-acetylhorminone (10) against Staphylococcus aureus ATCC 6538 P, Staphylococcus epidermidis ATCC 12226, and Bacillus subtilis ATCC 6633. Horminone was also found to be active against Enterococcus faecalis ATCC 29212.