Enmein-type diterpenoids from the aerial parts of Isodon rubescens and their cytotoxicity.

Three new enmein-type diterpenoids, jianshirubesins A-C (1-3), together with ten known compounds, were isolated from the aerial parts of Isodon rubescens. Their structures were established by using spectroscopic methods, and the absolute configuration of compound 1 was confirmed by a single-crystal X-ray diffraction analysis. All compounds except 3 were evaluated for their in vitro cytotoxicity by MTT assay, and compounds 5 and 10 exhibited significant inhibitory ability on selected cell lines.