| Summary: | 碩士 === 臺灣大學 === 農業化學研究所 === 98 === This study was to find out the potential of urolithin A, urolithin B and bacterioruberin in whitening application of cosmetics. B16F0 cells were employed as the tested cells for evaluating the potent use of above three samples. B16F0 cells were treated by various concentrations of urolithin A, urolithin B and bacterioruberin. The concentrations of three samples, made the viability of B16F0 cells higher than 80% , were set as the highest concentration for further tests. The experimental works including the inhibition of melanin formation and tyrosinase activity of B16F0 cells as well as the corresponding mRNA expression of B16F0 tyrosinase were conducted in this study. The results revealed that the highest concentrations of three samples, without significant cytotoxic effect, were respective 10 μM for urolithin A, 10 μM for urolithin B and 3.75 nM for bacterioruberin, and the above concentrations of three samples incubated with B16F0 for 72 h could effectively reduce the melanin formation more than 23% in B16F0 cells. Urolithin A, urolithin B and bacterioruberin could not only inhibit the activity of B16F0 tyrosinase, but also inhibit the activity of mushroom tyrosinase. In addition, the results of RT-PCR revealed that there were no significant influences on the mRNA expression of B16F0 tyrosinase. Therefore, we suggested that the melanin formation of B16F0 cells reduced by urolithin A, urolithin B and bacterioruberin could be attributed their capabillity to act directly with the tyrosinase of cells. Furthermore, the results from the enzyme kinetics studies of tyrosinase inhibited by urolithin A, urolithin B and bacterioruberin revealed that all tested samples were the same mode of competitive inhibition toward the L-DOPA substrate of B16F0 tyrosinase.
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