| Tyrosinase(EC 1.14.18.1), the key enzyme in melanin synthesis is a binuclear copper ions oxidase. It is a kind of polyphenol oxidase which widely exists in microorganisms, plants and animals as well as human beings. Tyrosinase catalyzes two rate-limiting steps in the reaction: hydroxylation of tyrosine to L-Dopa and L-Dopa oxidized to dopaquinone, thus becoming one of the most important targets in research of melanogenesis regulation. Studies on its activity have been paid attention increasingly.Our study focused on effects of Phellodendron extracts(PLF)and phellamurin on tyrosinase activity.First we conducted docking simulation between mushroom tyrosinase and the main compounds in PLF, inferred its inhibition on tyrosinase. By spectrophotometry, and fluorescence quenching, we testified the results and found that PLF was a reversible mixed inhibitor with the IC50 value of 0.1mg/m L, and the inhibition constants Ki and Kis were 455.99 mM and 95.67 mM. PLF had a quenching effect on tyrosinase intrinsic fluorescence, showing no effect on changes of maximum peak wavelength.Experiments results showed phellamurin promoted the activity of tyrosinase and had a dose-dependent quenching effect on tyrosinase intrinsic fluorescence. Ksv was 9.144E3L/mol and Kq was 9.144E11 L ? mol-1 ? s-1 at pH 6.24, while Ksv was 11.49E3L/mol and Kq was 11.49E11 L ? mol-1 ? s-1 at pH 7.17, indicating the effect was due to the formation of the complex caused by static quenching. Then phellamurin ointment was prepared for vitiligo mouse model. Compared with the normal control group, the number of follicles containing melanin in negative group decreased 10.12% while the number of phellamurin group decreased 5.81%, suggesting its possible efficacy on vitiligo.In our study, PLF was identified as a tyrosinase inhibitor and phellamurin was a activating agent for tyrosinase, providing theoretical basis for their application on skin whitening or treatment of vitiligo. |
PDF Full Text Request