麴酸及維他命C在美白加成功效之研究

許多愛美的女性在美容保養上花盡心思，對美白肌膚更是不遺餘力，使得近年來美白化妝品發展神速。但市面上有各種不同的美白產品，美白功效如何？一直無法有明確的標準可提供消費者判定產品功效的機制，所以利用大家熟知美白功效顯著的麴酸 (Kojic acid)及維他命C (L-Ascorbic acid)，建立一套美白的檢測比對機制，讓不同的美白產品在抑制黑色素 (Melanin)生成能力有比對依據的標準；及利用奈米粒子包裹美白藥物，降低其氧化速度，將可達到良好美白功效所需的劑量降到最低，並且在奈米粒子降解後緩慢地持續釋放藥物，進而達到長效的美白。實驗內容分為兩部分，使用HPLC在螢光(ex：281 nm、em：341 nm)測量酪胺酸及多巴，來判定黑色素生成量。第一部分：單純加入麴酸 (4μM、32μM、64μM、128μM)或維他命C (40μM、320μM、640μM、1280μM)及對照組 (PBS)。實驗結果中在單獨加入麴酸部分：除了濃度4μM與對照組生成酪胺酸及多巴的量相差不多外，其他隨著濃度的增加，減緩酪胺酸的消耗量及延緩多巴生成、消耗的時間。在加入單獨維他命C部分：濃度增加至1280μM，酪胺酸的量依然與對照組相近沒有差別，多巴的量會隨著濃度增加而增加並延緩消耗掉的時間。同時加入不同濃度的麴酸及維他命C，去探討兩種不同抑制方式相加時，是否會使美白功效加乘，或者會互相影響使美白效果降低。維他命C是一種極易氧化的物質，結果顯示高濃度的麴酸可保護維他命C延緩氧化速度，使多巴的量在30分鐘後維持一定濃度，進而延緩黑色素生成時間。第二部分：因維他命C很容易被氧化，為了使其能維持更長效的抗氧化能力，所以將奈米粒子PLGA來包裹維他命C，並利用PLGA緩慢降解釋放維他命C，延長維他命C的使用有效時間。結果顯示由上清液來看，PLGA包裹維他命C的包覆率約可達到90 %，更進一步來探討其緩慢釋放成效。

關鍵字

黑色素；麴酸；維他命C

並列摘要

Women usually spend a lot of time on embellishing their looks, especially on skin whitening which makes cosmetic industries develop products very quickly. There are many different kinds of skin whitening products on the market, but we cannot find a standard reference to estimate their efficacy for consumers. Therefore, in our experiments we studied the synergistic effects of two skin whitening compounds : “ascorbic acid” and “kojic acid”. Additionally, we tested to employ nanoparticles to encapsule whitening agent to decrease the oxidizing rate. And thus we can lower the whitening compound concentration and extend the efficiency time by degrading the nanoparticles. There are two major parts in our experiment. In the first part, we added kojic acid (4 μM、32 μM、64 μM、128 μM) or ascorbic acid (40 μM、320 μM、640 μM、1280 μM) into solutions containing both tyrosine and tyrosinase. We then measured tyrosine and dopa concentrations to estimate the concentration of melanin by HPLC. From the result, we found that increasing the concentration of kojic acid can reduce the consumption of tyrosine and delay the rate of the production of dopa except the concentration of kojic acid about 4 μM. Increasing the concentration of ascorbic acid can increase the concentration and delay the production of dopa. We also mixed different kind of concentration of kojic acid and ascorbic acid to ensure if these compounds will enhance each other to skin whitening or decrease the skin whitening efficiency. We found that higher concentration of kojic acid can maintain the vitamin C activity and therefore the concentration of dopa can be maintained during 30 mins which can decrease the rate of prodution of mananin. Because ascorbic acid will be oxidized easily, we use PLGA to encapsulate it for maintaining its activity and PLGA can release it slowly by degrading for long-time antioxidant activity. From the supernatant fluid result, we know the loading efficiency is about 90%¸ and we want to know the effect by slowly releasing.