Study on the synergistic effects of kojic acid and ascorbic acid on skin whitening

• Main Authors: Ya-Ling Chang, 張雅鈴
• Other Authors: Chung-Shi Yang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/36668957691808268947

碩士 === 國立暨南國際大學 === 應用化學系 === 99 === 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.