Berberine is an alkaloid extracted from Coptidis rhizome. Among the individual herbal components of a Chinese herb medicine, Ching-Wei-San, Coptidis Rhizoma has the most potent antimicrobial activity. By high-pressure liquid chromatography, the quantitative analysis of berberine from 6.25-mg/mL (w/v) Coptidis rhizome extract or 50.00-mg/mL (w/v) Ching-Wei-San was determined to be 0.26 mg/mL. To explore the potential use of Ching-Wei-San against herpes simplex virus (HSV) infection, the cytotoxicity, anti-HSV-1 and anti-HSV-2 activity in Vero cells were assayed. The selectivity index of berberine was about 1.2–1.5 times higher than that of Coptidis rhizome extract and Ching-Wei-San. Moreover, the antiviral activities correspond to the content of berberine in the aqueous solution. Berberine may interfere with the viral replication cycle after virus penetration and no later than the viral DNA synthesis step, and its activities were not affected by the preparation processes. Berberine, the natural plants that contain this component, including Coptidis rhizome, and Ching-Wei-San have all shown anti-HSV effects
