The Inhibitory Effect of Polyphenon 60 from Green Tea on Melanin and Tyrosinase in Zebrafish and A375 Human Melanoma Cells

Abstract

Polyphenon 60 (PP60) from green tea has long been used as an antioxidant, anticancer, antimicrobial, and antimutagenic. Aim of the Study. To investigate tyrosinase inhibition-related kinetic mechanism and antimelanogenesis potential of PP60. Materials and Methods.,e e`ect of PP60 on melanin and tyrosinase was evaluated in A375 melanoma cells and zebra"sh embryos.,e melanoma cells were treated with 20, 40, and 60 mu g/mL of PP60, and tyrosinase expression was induced by using L-DOPA.,e western blot method was used for the evaluation of tyrosinase expression. Cell lysates were prepared from treated and untreated cells for cellular tyrosinase and melanin quanti"cation. Furthermore, zebra"sh embryos were treated with 20, 40, and 60 mu g/mL of PP60 and reference drug kojic acid for determination of depigmentation and melanin quanti"cation. In vitro assays were also performed to examine the impact of PP60 on mushroom tyrosinase activity. To determine cytotoxicity, MTT was used against melanoma cell line A375. Results. PP60 showed good tyrosinase inhibitory activity with an IC50 value of 0.697 +/- 0.021 mu g/mL as compared to kojic acid a reference drug with an IC50 value of 2.486 +/- 0.085 mu g/mL. Kinetic analysis revealed its mixed type of inhibition against mushroom tyrosinase. In addition, western blot analysis showed that at 60 mu g/mL dose of PP60 signi"cantly reduced L-DOPA-induced tyrosinase expression in melanoma cells. PP60 signi"cantly inhibits the cellular tyrosinase (p < 0.05) and reduces the melanin (p < 0.05) contents of melanoma cells. Furthermore, PP60 was found to be very potent in signi"cantly reducing the zebra"sh embryos' pigmentation (p < 0.05) and melanin (p < 0.05) content at the dose of 60 mu g/mL. Conclusions. Our results demonstrate that PP60 has a strong potency to reduce pigmentation. It may be useful for the cosmetic industries to develop skin whitening agents with minimal toxic e`ects.