克弗爾於皮膚特性影響之研究

Abstract

克弗爾為一種由乳酸菌及酵母菌共同發酵之酒精發酵乳，其內之複雜菌種主要由克弗爾粒於發酵過程中轉移至乳中。研究顯示克弗爾中所含之益生菌、益菌質及許多具生物活性之成分包含：肽、多醣體、有機酸，對於生理功能有助益，而這些成分或許對於皮膚具有改善之功能。本研究旨在探討克弗爾中之不同成分(克弗爾、克弗爾乳清、肽類、醣類、菌之胞內萃取物、乳酸)，對於美白、抗氧化及痤瘡治療是否具有功效，最後之目標為將克弗爾開創為一新美容產品，以提升畜產品之利用價值，拓展其應用領域。 在美白試驗中，主要以酪胺酸酶之抑制活性及動物試驗來做評估。黑色素主要由酪胺酸藉由酪胺酸酶之催化，經過一連串之反應所形成，故減少黑色素的形成可藉由抑制酪胺酸酶活性達成。結果顯示，乳酸在8mg/mL的添加下，於10分鐘後之黑色素生成可達IC50，濃度提升為10mg/mL時，酪胺酸酶已不具活性，推測應是pH值影響所致。於動物試驗中，經克弗爾處理組別則未展現出明顯之美白效果。証據顯示，自由基的形成對於皮膚之老化有顯著影響，故本研究以銅離子螯合能力做為克弗爾抗氧化能力之指標，推測克弗爾是否具有抗老化之功能。結果發現乳清、肽類、醣類、菌之胞內萃取物均對銅離子產生螯合能力，顯示克弗爾具有明顯之抗氧化活性。對於痤瘡改善，乳酸於濃度為60mg/mL及10mg/mL分別對痤瘡桿菌及表皮葡萄球菌產生抑制能力，相較於此二株菌對酸環境及抗生素耐受性之不同，或許可供治療炎性痤瘡之參考。 目前結果顯示克弗爾中之部分成分對於美白、抗氧化及治療痤瘡具有部分成效，未來將以其中有效成分之分離、純化為目標，以確定克弗爾中各項成分於皮膚改善之特性。

Kefir is a cultured milk beverage produced by microbial action of a wide community of microorganisms presented in kefir grains on milk. Kefir can be considered to be a carrier of probiotics and various bioactive compounds, including peptide, polysaccharide and organic acid that may play a functional role for skin care. Thus, the purpose of this research is to study the effects of different kefir components (kefir, whey, peptide, saccharide, intracellular extract, lactic acid) on skin properties including skin whitening effect, antioxidative activity and acne treatment. The final aim is to develop a new cosmetic product for its possible commercialized and enhance the value of dairy products. The skin whitening tests were performed by tyrosinase assay and animal experiments. The melanin synthesis is regulated by tyrosinase, which catalyzes the conversions of tyrosine to dopa and dopa to dopaquinone. Inhibition of tyrosinase activity reduced the melanin production. The results showed that lactic acid had better inhibitory ability agaist melanin synthesis. However, application of kefir on the skin of hamsters did not find a significant skin whitening effect. A vast amount of evidence implicates oxygen-derived free radicals as important causative agents of aging. Therefore, the antioxidative activities of kefir components were determined by cupric ion chelating analysis and results demonstrated that certain kefir components had antioxdative activities. The ability of acne treatment was performed by inhibition of Propionibacterium acne and Staphylococcus epidermidis, which commonly isolated from pustular acne lesions. The results indicated that lactic acid level higher than 60 and 10mg/mL could inhibit the growth of Propionibacterium acne and Staphylococcus epidermidis, individually, while no inhibition was found for other components. Although the present study demonstrated that certain kefir components had skin whitening effect and antioxdative activity, further study is necessary to separate and identify the components which might improve the skin and its properties.