Purified alkaloid extract of Scutellaria barbata inhibits proliferation of hepatoma HepG-2 cells by inducing apoptosis and cell cycle arrest at G 2 /M phase

Scutellaria barbata was widely used as an antitumor agent in traditional Chinese medicine. However, its antitumor components and mechanism remained unclear. In the present study, the effects of purified alkaloid extract of Scutellaria barbata (PAESB) on the cultured hepatoma HepG-2 cells were investigated. 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay showed that PAESB could inhibit the proliferation of HepG-2 cells in a dose- and time-dependent manner. Annexin V-FITC and propidium iodide (PI) staining showed that PAESB had a positive effect on apoptosis of HepG-2 cells. After treatment by PAESB (0.75 mg/ml) for 48 h, the HepG-2 cells apoptosis rate (25.12±0.91%) had statistical significance as compared with the negative group (2.97±0.49%) (P<0.01). Among the various phases of cell cycle, significant increase in the percentage of G2/M phase occurred after treated with PAESB (0.75 mg/ml) for 48 h by comparison with the corresponding values for HepG-2 cells without PAESB (P<0.01). These results indicated that PAESB exhibited potential anticancer activity against hepatoma HepG-2 cells through induction of apoptosis and G2/M phase cell cycle arrest.  Key words: Scutellaria barbata, purified alkaloid extract, apoptosis, cell cycle arrest, hepatoma HepG-2 cells.