In vitro cytotoxicity of tanshinones from Salvia miltiorrhiza.

The cytotoxicity-guided fractionation of the roots of Salvia miltiorrhiza B. (Labiatae) extracts led to the isolation of eighteen active principles 1-18, responsible for the cytotoxicity against five cultured human tumor cell lines, i.e., A549 (non-small cell lung), SK-OV-3 (ovary), SK-MEL-2 (melanoma), XF498 (central nerve system) and HCT-15 (colon), using the SRB (sulfrhodamine-B) method in vitro. All active compounds 1-18 including two novel components 5 and 11 were comprised of tanshinone pigments, unusual diterpenes exclusively found in this species. The proliferation of each examined tumor cell line was significantly inhibited (IC50 values ranged from 0.2 to 8.1 micrograms/ml) during the continuous exposure of tumor cells to 1-18 for 48 hours, respectively.