目的 研究库拉索芦荟中7种单体化合物对蘑菇酪氨酸酶催化氧化左旋多巴的活力的影响，并确定活性成分的抑制类型。方法 以左旋多巴为底物，37 ℃条件下，以酶标仪记录反应体系在475 nm下光密度随时间的变化，通过相对酶活力比较加药后酶活力的变化，并通过Lineweaver-Burk曲线判定抑制类型，通过Dixon曲线求抑制常数。结果 库拉索芦荟中的芦荟苦素具有很强的蘑菇酪氨酸酶抑制作用，且强于β-熊果苷，其50 %抑制浓度(IC50)为108.6 μg·mL-1，抑制类型为非竞争性抑制，抑制常数Ki=130.9 μg·mL-1，而其余6种化合物的抑制作用较弱或没有抑制作用。结论 芦荟苦素是库拉索芦荟中主要的蘑菇酪氨酸酶抑制成分。

Objective To evaluate the effects of seven compounds from Aloe barbadensis Mill on the activity of mushroom tyrosinase in the catalysis of levodopa，and to determine the inhibition type of active components. Methods Tyrosinase activity was measured by the absorbance variations accompanying with the oxidation of the substrate levodopa which were recorded with a microplate reader at 475 nm under a constant temperature of 37 ℃. Inhibition type was determined by Lineweaver-Burk plot，and inhibition constant(Ki) was calculated by Dixon graphs. Results Aloesin was a strong noncompetitive inhibitor of mushroom tyrosinase and was more potent than arbutin，with an IC50 value of 108.6 μg·mL-1 and a Ki value of 130.9 μg·mL-1. The other compounds had weak activities or even had no activities. Conclusion Aloesin is the main mushroom tyrosinase inhibitor in Aloe barbadensis Mill.

R285.5

2012年度“十二五”农村领域国家科技计划课题“区域特产资源生态高附加值加工质量安全控制关键技术研究”(2012BAD36B02)。