Anti-tumour mechanisms of Scutellaria barbata

Medicinal plants have been used as traditional remedies for hundreds of years. Among them, S. barbata has been traditionally used in treatment of hepatitis, inflammation, osteomyelitis and gynecological diseases in China. Studies indicate that extracts from S. barbata have growth inhibitory effects on a number of human cancers. Reports are available on the treatment of lung, breast and digestive system cancer, hepatoma, and chorioepithelioma with S. barbata extracts. However, the underlying mechanism of the antitumor activity of S. barbata extracts remains unclear.

A research article to be published on December 28, 2008 in the World Journal of Gastroenterology addresses this question. The research team led by Dr. Zhi-Jun Dai from the Medical School of Xi'an Jiaotong University studied the growth inhibitory effects of S. barbata and determined its mechanism of antitumor activity in mouse liver cancer cell line H22.

They found that ESB could inhibit the proliferation of H22 cell in a time dependent manner. Among the various phases of cell cycle, the percentage of cells in S phase was significantly decreased, while the percentage of cells in G1 phase was increased. Flow cytometry assay also showed ESB had positive effect on apoptosis. Typical apoptotic morphology such as condensation and fragmentation of nuclei and blebbing membrane of the apoptotic cells could be observed through transmission electron microscope and fluorescence microscope. Further investigating the molecular mechanism behind ESB-induced apoptosis, cells treated with ESB underwent a rapid loss of mitochondrial transmembrane potential(delta psi m), release of mitochondrial cytochrome c into cytosol, induction of caspase-3 activity in a dose-dependent manner. This may offer new evidence for S. barbata in the treatment of hepatoma in clinical practice.