胞外菇類酪胺酸酶活性與A2058黑色素細胞之酪胺酸酶活性及黑色素形成能力之相關性   全文下載

The Correlation of in Vitro Mushroom Tyrosinase Activity with Cellular Tyrosinase Activity and Melanin Formation in Melanoma Cells A2058

酪胺酸?是促進皮膚黑色素形成的限制酵素，因此許多宣稱具有美白效果的藥粧品通常都是藉由該樣品在體外系統抑制酪胺酸?活性之能力，以評估其美白效果。然而，活體外（或胞外）酪胺酸?活性的抑制試驗並不包括細胞對樣品的吸收能力，因此其適用性仍有疑問。本研究的目的乃為探討胞外酪胺酸?（來自菇類）活性及黑色素細胞（A2058 細胞）酪胺酸?活性與A2058 黑色素細胞黑色素形成間的相關性，以期了解篩選較具有美白能力樣品的適當的方法；所使用的材料包括：麴酸、抗壞血酸、七種傳統用於美白功能之中藥材水萃取物（S1-S7），以及上述七種藥材依固定比例，以水、酒精或乙酸乙酯在不同溫度下萃取所得的複方萃取物（M1-M7）。研究結果發現，無論胞外與胞內酪胺酸?活性之抑制（r = 0.37, p = 0.25, n = 16）、胞外酪胺酸?活性與胞內黑色素形成之抑制（r = 0.32, p = 0.28），或胞內酪胺酸?活性與胞內黑色素形成之抑制（r = 0.18, p = 0.43）均無顯著之相關性。然而，以UVA 照射A2058 細胞能顯著促進胞內酪胺酸?活性抑制能力與黑色素形成抑制能力之間的相關性（r = 0.97, p < 0.001）。因此利用UVA 照射黑色素細胞瘤細胞A2058 之篩選平台可以用來評估有潛力之中草藥抽取物。"

The inhibition of mushroom tyrosinase activity in vitro has commonly been employed for evaluation of the whitening effects of various drugs and cosmetic products because tyrosinase is the limiting enzyme in melanin formation in skin. However, questions remain as to whether the in vitro inhibition of tyrosinase activity adequately represents the whiting effects since it does not account for cellular uptake of test samples. We therefore evaluated the correlations of the inhibition of cell-free mushroom tyrosinase activity with that of cellular tyrosinase activity and melanin formation in A2058 melanoma cell line using kojic acid, ascorbic acid and water extracts of seven Chinese herbs and seven mixtures of these herbs extracted with water, ethanol or ethyl acetate at different temperatures. No significant correlation was found for the inhibition of: (1) mushroom tyrosinase activity vs. cellular tyrosinase activity (r = 0.37, p = 0.25, n = 16) or vs. cellular melanin formation (r = 0.32, p = 0.28); and (2) cellular tyrosinase activity vs. cellular melanin formation (r = 0.18, p = 0.43). Ultraviolet A irradiation of melanoma cells A2058 markedly improved the correlation between the inhibition of cellular tyrosinase and of melanin formation of these samples (r = 0.97, p < 0.001). The results suggest that UVA irradiation of melanoma A2058 cells be a useful screening method for evaluating the potential whitening effect of Chinese herbs.