Neoclerodane diterpenoids from Scutellaria barbata.

Eight new neoclerodane diterpenoids (1- 8), scutebatas H-O, together with eight known compounds, have been isolated from the whole plant of Scutellaria barbata D. Don. Their structures were elucidated on the basis of spectroscopic studies. In vitro cytotoxicity of selected compounds against cancer cell lines HL-60, SMMC-7721, A-549, MCF-7, and SW480 was evaluated. Compounds 5, 6, 7 showed moderate cytotoxicities against several human cancer cell lines, with IC50 values ranging from 12.6-31.4 µM. In addition, compound 1 showed selective cytotoxicity against MCF-7.