Abstract

Fifty important cosmetic skin-whiting traditional Chinese medicines (TCMs) were investigated for their anti-tyrosinase and antioxidant (or DPPH-free-radical-scavenging) activities. The water and 70% ethanol extracts (WEs and 0.7EtEs, respectively) of TCMs were tested for tyrosinase inhibitory activities and DPPH-free-radical-scavenging activities. The 10 mg/ml WEs of 6 TCMs, Angelica dahurica, Anredera cordifilia Moq., Cinnamomum aromaticum, Glycyrrhiza glabra, Melia toosendan, and Prunus davidiana, presented over 50% inhibitory effect (referred to as the positive control of 0.5  mg/ml vitamin C) in tyrosinase activity, while Prunus davidiana showed the best anti-tyrosinase activity (94.0%). Only 3 TCMs of 0.7EtEs, Cinnamomum aromaticum, Quisqualis indica, Areca catechu, exhibited over 50% anti-tyrosinase activity. Among the TCMs screened, the 10mg/ml 0.7EtEs of Evodis rutaecarpa, Leonurus heterophyllus, Nardostachys chinensis, and Quisqualis indica, had strong DPPH-free-radical-scavenging effects or antioxidant activities (96.0, 90.5, 92.6 and 80.6%, respectively), while all the WEs of TCMs, except Uncaria sessilifructus Roxb, showed low antioxidant activities (65.6%). The anti-tyrosinase and antioxidant activities of these two TCM extracts may be due to direct linkage to the contents of their active compounds.

Key words: Traditional Chinese medicines, inhibition, anti-tyrosinase, antioxidant, free radical scavenging.