Filtration Of Active Component From Coleus Forskohlii Briq. And Its Inhibitory Effect On The Proliferation Of Tumor Cells

Coleus forskohlii Briq.,a perennial herb belongs to the Coleus genus of the Labitae.Pharmacological researches have shown that Coleus forskohlii Briq. possesses significantlycurative effects to against asthma, acute and chronic bronchitis, heart diseases, tumor andglaucoma.Combined with the separation and pharmacological techniques, nature active componentColeon C (6,11,12,14,16-pentahydroxyabieta-5,8,11,13-tetraen-7-one) was filtrated out. Themechanism of inhibitory effects of Coleon C on the proliferation of tumor cells was exploredin three levels, involved animal level, cell level and molecule level, so as to find a newanti-tumor drug with low toxicity.Through MTT assay, we got Coleon C from Q3, which was crudely filtrated from Coleusforskohlii Briq. And then cytotoxicity and influence of Coleon C on eight human cancer celllines (95-D, A375, HeLa, A431, MKN45, BEL7402, LoVo and HL60) and two normal ones(293, L02) were investigated by MTT and colony-forming assay. Results indicated that HL60was the most sensitive cell line, followed by A375. Hoechst 33258 staining showedfragmentation and condensation of chromatin and DNA ladder assay showed the fragments ofDNA because of apoptosis. Flow cytometric analysis demonstrated hypodiploid cells in thesetumor cells treated with Coleon C. RT-PCR results demonstrated that Coleon C downregulatedBcl-2 gene level with a dose-dependent manner. Meanwhile there was a littleincrease of Bax gene level in HL60 cells. The resulting net effect could thus lead to a lowerratio of Bcl-2/Bax, which might be one of the key factors of the common final pathwayinvolved in the regulation of cell apoptosis.In the acute toxicity studies in C57BL/6 mice, the LD50 of Coleon C was 1496±285mg/kg. In the model of Lewis lung carcinoma, the average tumor weights in 80mg/kg ColeonC injection groups decreased by 45.7±11.3％compared with those of the control.These results indicated that Coleon C could effectively inhibit tumor cells growth andproliferation through inducing apoptosis of the tumor cells with low toxicity. To ourknowledge, this is the first research on the anti-tumor activity of Coleon C both in vitro and invivo.