Dawson结构的多金属氧酸盐对酪氨酸酶的抑制作用

按文献方法合成了两种Dawson结构的多金属氧酸盐,并对其结构进行紫外光谱和红外光谱分析。以H_6P_2Mo_(18)O_(62)]和H_8P_2Mo_(17)Cr(OH_2)O_(61)](简写为P_2Mo_(18)和P_2Mo_(17)Cr)为效应物,采用紫外分光光度法和酶动力学方法研究两种Dawson结构的多金属氧酸盐效应物对蘑菇酪氨酸酶二酚酶活性的抑制作用。结果表明,P_2Mo_(18)和P_2Mo_(17)Cr对酪氨酸酶二酚酶均具有显著的抑制效果,测定抑制酪氨酸酶活力下降50%的抑制浓度(IC_(50))分别为(0.482±0.009)mmol/L和(0.503±0.011)mmol/L。动力学分析表明,P_2Mo_(18)和P_2Mo_(17)Cr对酪氨酸酶的抑制作用均表现为可逆的竞争型,抑制常数K_I分别为0.212和0.249 mmol/L。其中,综合考虑IC_(50)值和抑制常数,P_2Mo_(18)对酪氨酸酶二酚酶活性的抑制效果略优于P_2Mo_(17)Cr。

Inhibitory Effects of Dawson Type Polyoxometalates on Tyrosinase

Tyrosinase is a complicated copper containing oxidoreductase that is common in microorganism, plants, animals and human body, which plays a crucial role in melanin biosynthesis. Currently researches about tyrosinase inhibitors are mostly focused on natural extracts and organism. However, inorganic Dawson type polyoxometalates as tyrosinase inhibitors have been less reported. Two kinds of Dawson type polyoxometalates were synthesized and characterized by ultraviolet spectroscopy and infrared spectral analysis. The inhibitory effects of H₆P₂Mo₁₈O₆₂] and H₈P₂Mo₁₇Cr(OH₂)O₆₁](abbreviated to P₂Mo₁₈ and P₂Mo₁₇Cr, respectively) on mushroom tyrosinase were investigated by ultraviolet spectrophotometry and enzymatic kinetics methods. P₂Mo₁₈ and P₂Mo₁₇Cr have significant inhibitory effects on tyrosinase, and the IC₅₀ values of P₂Mo₁₈ and P₂Mo₁₇Cr are (0.482±0.009) mmol/L and (0.503±0.011) mmol/L for diphenolase, respectively. Enzymatic kinetics analysis indicates that P₂Mo₁₈ and P₂Mo₁₇Cr are reversible and competitive inhibitor, and the inhibition constant of P₂Mo₁₈ and P₂Mo₁₇Cr are 0.212 mmol/L and 0.249 mmol/L, respectively. Considering of IC₅₀ values and inhibition constants, the inhibitory effect of P₂Mo₁₈ is slightly better than that of P₂Mo₁₇Cr. In conclusion, P₂Mo₁₈ and P₂Mo₁₇Cr show effective antityrosinase activities. Compared with arbutin, P₂Mo₁₈ and P₂Mo₁₇Cr have much more inhibitory effects on the diphenolase activity of tyrosinase. This study may provide reference foundation for the further study of the tyrosinase inhibitors, and also offer useful information for the comprehensive utilization of polyoxometalates.