| 摘要: | 具有防曬、美白概念之相關化粧保養品一直都是化粧保養品市場上長青型之明星商品，各大知名化粧品廠商無不積極開發新配方、新劑型以達到此訴求。此外，亦積極投入相關研究藉此找尋具有防曬、美白概念之新型有效成分。目前，欲評估新型有效成分之防曬、美白幼纂A大多藉由酪胺酸酶（tyrosinase）活性抑制程度或抑制黑色素瘤細胞（melanoma cell）之黑色素生成之程度來評估。但利用這些方法所評估之結果，常被質疑與正常皮膚生理狀況相距甚遠。在服膺全世界禁止使用動物進行活體試驗之大前提下，本研究旨在建立一個更接近實際人類皮膚生理狀況之評估黑色素生成的細胞模式，用以評估各類藥粧成份（cosmeceuticals）及植物萃取物（botanical extracts）對於黑色素生合成（melanogenesis）之影響。
為建立更接近人類皮膚實際生理狀況之細胞模式，我們以人類皮膚黑色素細胞建立此細胞模式，並建立此測試平台之各種實驗條件，如UVB照射劑量及角質細胞對黑色素細胞生成黑色素之影響。在確立所有之測試條件後，比較本模式與其他細胞模式之差異。另外，利用此細胞模式以已知具有美白概念之藥粧成份（如：麴酸、熊果素、維生素C及對苯二酚）或宣稱具美白效力之植物萃取液（如：菊花、黃芩、桑白皮及月見草等）進行抑制黑色素生成之效力評估，藉以了解此細胞模式之應用條件、潛力及價值。
在此細胞模式之實驗條件測試中我們發現，人類黑色素細胞以未經UVB照射之角質細胞上清液進行培養，並經過UVB照射後會增加黑色素生合成的量。另外，人類黑色素細胞與B16細胞模式，對於評估美白成分抑制黑色素生成之效力存在差異。維生素C及黃芩萃取液皆具有抑制UVB所引發之黑色素生成之效力。我們認為此細胞模式可應用於美白化粧品新成份之開發及篩選 之參考依據。
Sun-protecting and whitening are always the key issues in the cosmetics. Some of the major cosmetic manufacturers dedicate themselves in finding new ingredients, refining formulations or developing new techniques to reach such claims. Nowadays, the new concept of “cosmeceuticals”, the pharmaceutical cosmetics, has shed a light on the development of cosmetics. Moreover, the claims of natural and earth-caring have also brought out a new faith on botanical-oriented cosmetics. Evidences are accumulated to support that there are several botanical extracts and so-called cosmeceuticals have their effects on sun-protection, whitening, smoothing wrinkles, holding moisture, skin firmness, anti-aging and re-juvenile. Manufacturers are beneficial to these scientific evidences, because consumers will be easily convinced to use such products have cosmeceuticals or botanicals within. Since the cosmeceuticals and botanicals turn out to be the stereotypes of cosmetic efficacy, it is very important to establish evaluating systems to confirm their major claims.
The widely-used in vitro systems that applied to evaluation of the inhibitory effects on melanin biosynthesis, such as inhibitory effect on tyrosinase activity and melanoma cell model, are considered to be far from the real situation of human skin. Since the use of animal model was excluded from the cosmetic development due to the ethic issue, we utilized the human melanocyte to establish a cell model that mimics the circumstance of real skin under UV irradiation.
First of all, we set up all the experimental criteria in order to standardize the tests of all candidate ingredients. The dosage of UVB was chosen not to damage melanocyte too much, that is more like the actual situation that happens to the real skin. In consideration of the melanin contain, we chose 302 nm UVB to challenge cell by the dosage of 1.2mJ/cm2, and melanocyte seems to be able to tolerate such UVB dosage. The influence of keratinocyte was also included by the addition of conditional medium, which contains 50% medium retrieved from the cultured human keratinocyte, to cultivate human melanocyte. The whitening cosmeceuticals, such as L-ascorbic acid, kojic acid, ?arbutin, and hydroquinone, were used for the purpose of characterizing this melanocyte model, moreover, we can thus know the matter of apply.
The efficacies of botanical extracts and cosmeceuticals can not be just evaluated by the use of abnormal cell or the inhibition of a single enzyme, it will result in narrow-focusing and misleading. Although the tyronsinase model is obvious unrepresentative, the B16 melanoma model still digress the representation of evaluations. Except that the B16 melanoma cell was vulnerable to the UVB irradiation than melanocyte, it over-estimated the inhibitory efficacy of L-ascorbic acid on melanogenesis.
According to our observations, the human melanocyte model can be used to interpret not only the inhibition of melanogenesis, it can also provide broad view of melanin biosynthesis. It can be applied not only to evaluation of the efficacies of whitening, but also tanning . Moreover, for the purpose of establishing a representative in vitro evaluation system, the influences of cosmetic ingredients on keratinocyte should also be considered to make proper evaluation and interpretation. |
