睡莲花提取物对酪氨酸酶的抑制作用及其动力学研究

采用紫外分光光度计测定多巴醌,得到了睡莲花提取物对酪氨酸酶的抑制率;以L-酪氨酸为底物,采用酶动力学的方法研究了睡莲花提取物对酪氨酸酶单酚酶活性的抑制作用及抑制机制。结果表明,睡莲花提取物对酪氨酸酶具有明显抑制作用,其中30%乙醇洗脱部位抑制效果最好,其对酪氨酸酶单酚酶活性的抑制作用表现为可逆反竞争型抑制;50%乙醇洗脱部位对酪氨酸酶单酚酶活性的抑制作用表现为可逆性抑制,低浓度时为混合型,高浓度时为竞争型。

Inhibitory action of extracts from water lily flower on tyrosinase activity and its kinetics

Tyrosinase inhibitory ratio of extracts from water lily (Nymphaea candida Presl.) flower (70% ethanol extract, NCE; 30% ethanol elution parts, NCEA; 50% ethanol elution parts, NCEB) were obtained based upon determination of dopa quinone with ultraviolet spectrophotometer. Furthermore, the effect of the extracts on monophenolase activity of tyrosinase and its inhibiting mechanism were examined by enzyme reaction kinetics method adopting L-tyrosine as substrate. Results show that these extracts can obviously inhibit activity of tyrosinase, of which NCEA displays the best inhibition effect as comparing with that of NCE and NCEB. The inhibition of NCEA on monophenolase activity of tyrosinase displays as reversible anti-competitive inhibition; while NCEB displays as reversible inhibition with mixed inhibition under low concentration condition, and competitive inhibition under high concentration condition.