New cytotoxic neo-clerodane diterpenoids from Scutellaria strigillosa.

Three new neo-clerodane diterpenoids, named scutestrigillosins A-C (1-3), were isolated from the whole plant of Scutellaria strigillosa. Their chemical structures including absolute configurations were established on the basis of detailed physical data analyses. In vitro, the isolated three new compounds exhibited significant cytotoxic activities against four tumor cell lines (HONE-1, P-388, MCF7 and HT29), and gave IC50 values in the range 3.5-7.7μM.