Studies On The Screening And The Action Mechanism Of Whiting Plant Extracts

Hyperpigmentation is a kind of pathological variant caused by various internal and external factors and characterized by brown patches, including such diseases as chloasma, freckle, and melanosis. Due to varied limitations, the safe and successful treatments are lacking. It's showed that varied plant extracts can be used as a depigmenting agent according to the clinical trial. So, we made a study of the action mechanism of this effect on the basis of molecular biological principle.Fristly, our objective was to investigate the effects of twenty plant extracts (Green tea extract, Grape seed extract and so on) against tyrosinase activity and radical for further screening plant extracts, which possessed not only tyrosinase inhibitory activities but also anti-oxidant capacity significantly. Its results showed that twenty samples owned both tyrosinase inhibitory activities and anti-oxidant activities at various levels. Green tea extract (GSE), Grape seed extract (GSE) and Brizil large cherry extract (BLCE) exhibited stronger tyrosinase inhibitory activities and anti-oxidant capacity than others.In the second part, melanoma B16 cells were employed in this study, the interference of three plant extracts (GTE, GSE and BLCE) in the metabolism of melanocytes was evaluated, including effects on the proliferation of cells, tyrosinase activity and melanin content. It proved that three plant extracts had fewer effects on proliferation of cells, and at the same time it can inhibit the activity of tyrosinase and melanin biosynthesis of melanocytes. In addition , we found that GSE can down-regulate the protein expression of tyrosinase in murine B16 melanoma.Based on the studies of above mentioned mainly, (MRC-5) human fetal lung diploid fibroblast were employed in this study, The protective effect of three plant extracts (GTE,GSE and BLCE) against oxidative stress was evaluated using H2O2-induced oxidative stress of human diploid fibroblasts MRC-5 cell model. Our results showed three plant extracts attenuated H2O2-induced cellular oxidative damage. Our findings demonstrated that GSE can protect against oxidative stress/damage and H2O2-induced human diploid fibroblasts cell death.Finally, GTE, GSE and BLCE were analyzed by HPLC/LC-MS, the investigation found that effective components of three plant extracts maybe proanthocyanidins and vitamine C,which may determine the contribution to the total skin whiting properities. In the meantime, the efficiency evaluation of several extracts made from whitening cosmetic products was investigated. It is data that may provide material selection with reference to whitening Cosmetics industry.All the above evidences proved that GTE, GSE and BLCE can inhibit the melanin biogenesis, the direct reason is the reduction of protein expression of tyrosinase in melanocytes; the other is their markedly antioxidant and tyrosinase inhibition properties. So we suggest that the non-cellular mushroom tyrosinase inhibition experiment may be adopted as a kind of initial trail for the selection of new depigmenting compounds.while, the efficiency evaluation of depigmenting agent should be tested with tyrosinase activity inhibition experiment of melanocytes.