Purified alkaloid extract of Scutellaria barbata inhibits proliferation of nasopharyngeal carcinoma CNE-1 cells by inducing apoptosis and cell cycle arrest at S 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 S. barbata (PAESB) on the cultured nasopharyngeal carcinoma CNE-1 cells were investigated. MTT assay showed that PAESB could inhibit the proliferation of CNE-1 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 CNE-1 cells. After treated by PAESB (0.75 mg/ml) for 48 h, the CNE-1 cells apoptosis rate (5.13 ± 0.70%) had statistical significance as compared with the negative group (1.42 ± 0.26%) (P < 0.05). Among the various phases of cell cycle, significant increase in the percentage of S phase occurred after treated with PAESB (0.75 mg/ml) for 48 h while the percentage of cells at G0/G1 and G2/M phases were decreased by comparison with the corresponding values for CNE-1 cells without PAESB (P < 0.05). These results indicated that PAESB exhibited potential anticancer activity against nasopharyngeal carcinoma CNE-1 cells through induction of apoptosis and S phase cell cycle arrest.   Key words: Scutellaria barbata, purified alkaloid extract, apoptosis, cell cycle arrest, nasopharyngeal carcinoma CNE-1 cells.