中文摘要：

目的：研究西藏红缨合耳菊提取物对酪氨酸酶的抑制作用。方法：将红缨合耳菊的70％乙醇提取物依次用石油醚、乙酸乙酯、正丁醇萃取，然后测定各部分对酪氨酸酶的抑制作用，并进行酶抑制动力学研究。结果：乙酸乙酯、正丁醇的萃取部分对酪氨酸酶的活性抑制较强；对单酚酶抑制作用明显并有延迟作用，半数抑制浓度（IC50）分别为57．8、140μg/ml；对双酚酶的抑制作用显示浓度依赖关系，IC50分别为41．2、59．6μg/ml，相比熊果苷抑制双酚酶活性的IC50值1．44mg／ml，抑制效果分别是熊果苷的35、24倍；抑制类型：乙酸乙酯部分为竞争性抑制，Ki为19．7μg/ml，正丁醇部分为非竞争性抑制，Ki为60．7μg／ml。结论：西藏红缨合耳菊乙醇提取物的乙酸乙酯、正丁醇萃取部分对酪氨酸酶活性抑制较强。

英文摘要：

Objective ： To study the inhibition of extracts from Synotis erythropappa on tyrosinase. Methods ： The 70% ethanol extracts were extracted by petroleum benzine, ethyl acetate and n-butanol, and the inhibitory activities against tyrosinase of every fraction were determined in vitro and the inhibitory kinetics of ethyl acetate and n-butanol fractions were investigated. Results： The four fractions extracted all had inhibitory activities on tyrosinase, inhibitory activities of ethyl acetate and n-butanol fraction were higher. Their IC50 were 57.8,140 μg/ml for monophenol oxidase activity and 41.2,59. 6 μg/ml for diphenol oxidase activity, respectively. The inhibition kinetics analyzed by Hnewaver-Burk plots showed that ethyl acetate fraction was a competitive type inhibitor, and its Ki was determined to be 19. 7 μg/ml. n-butanol fraction was an uncompetitive type inhibitor, and its Ki was determined to be 60. 7μg/ml. Conclusion： Ethyl acetate and n-butanol fractions of extracts from Synotis erythropappa show potential inhibitory activity on tyrosinase.