根皮素与根皮苷对酪氨酸酶的抑制机制

Study on the molecular mechanism of enzyme activity inhibition difference between phloretin and phlorezin

目的研究根皮素与根皮苷对酪氨酸酶的抑制机制。方法采用紫外光谱法、高效液相色谱法、荧光光谱法和分子对接技术研究比较二者的单双酚酶活性,并从分子层面探索和比较二者的抑制机制。结果根皮素和根皮苷均具有单双酚酶活性抑制作用,单酚酶活性抑制能力源于二者的2,6-二羟基苯乙酮和2,4,6-三羟基苯基结构,导致双酚酶活力下降50%的抑制剂浓度(IC 50)分别为169.36和707.14μmol·L-1;根皮素和根皮苷均是酪氨酸酶的底物,而根皮素与酪氨酸酶的亲和力更强;根皮素和根皮苷均能使酪氨酸酶的内在荧光发生猝灭;分子对接表明根皮素与酪氨酸酶结合能低于根皮苷。结论根皮苷的酪氨酸酶抑制活性比根皮素低,二者抑制机制相似。研究结果为根皮素和根皮苷的进一步开发利用提供了理论依据和数据支持。

Objective This study was aimed to investigate the inhibitory mechanism of phloretin and phloretin on tyrosinase.Methods Ultraviolet spectroscopy,high performance liquid chromatography,fluorescence spectroscopy and molecular docking were used to compare the inhibition effects of the two inhibitors on tyrosinase,and the inhibition mechanism of both were explored and compared from the molecular level.Results Both phloretin and phlorezin had inhibitory activity of monophenolase and diphenolase activity.The inhibition of monophenolase activity may be derived from the structures of 2,6-dihydroxyphenylacetone and 2,4,6-trihydroxyphenyl.The inhibitor concentrations(IC 50)leading to a 50%decrease in diphenolase activity of phloretin and phlorezin were 169.36 and 707.14μmol·L-1,respectively.It was found that both phloretin and phlorezin were the substrates of the tyrosinase,and the affinity of phloretin to tyrosinase was stronger.Both phloretin and phlorezin could quench the intrinsic fluorescence of tyrosinase.The result of molecular docking indicated that the binding of phloretin to the tyrosinase was lower than that of phlorezin.Conclusion The tyrosinase inhibitory activity of phlorezin was lower than that of phloretin,but the inhibition mechanism of the two inhibitors was similar.These results provide theoretical basis and data support for further development and utilization of phloretin and phlorezin.