银杏叶和银杏外种皮乙醇提取物对酪氨酸酶的抑制作用比较

The Comparison of Inhibition of Ethanol Extracts of Leaves and Sarcotesta from Ginkgo biolaba on Mushroom Tyrasinase

报道银杏叶和银杏外种皮乙醇提取物对酪氨酸酶活力的影响.结果表明:银杏叶和银杏外种皮乙醇提取物对酪氨酸酶活力均有显著的抑制作用.测定导致酶活力下降50%的银杏叶和银杏外种皮提取物含量(IC50)分别为:6.59mg/mL和2.73mg/mL.对酪氨酸酶的抑制作用均表现为可逆抑制,抑制类型均为混合型.分别测定银杏叶和外种皮提取物对游离酶抑制常数(KI)和酶底物络合物抑制常数(KIS),并加以比较.

Ginkgo biolaba is a kind of medicinal plant.It has the function of antioxidation,anticancer,antifungal,immunity and so on.In this paper,the ethanol extracts from Ginkgo biolaba leaf and Ginkgo biolaba sarcotesta were used to test the inhibition on the activity of mushroom tyrasinase.The results showed that ethanol extracts from Ginkgo biolaba leaf and Ginkgo biolaba sarcotesta could inhibit the activity of tyrosinase obviously.The inhibitor concentration leading to 50% enzyme activity lost,IC_50 ,was estimated to be 6.59 and 2.73 mg/mL,respectively.Their inhibition mechanism was analyzed and the results showed that the ethanol extracts from Ginkgo biolaba leaf and Ginkgo biolaba sarcotesta were reversibly inhibitors to tyrosinase and the inhibition belonged to the mix-typed.The inhibition constants,K_I and K_IS ,of each extracts were determined respectively and compared.The inhibition of the ethanol extracts from Ginkgo biolaba leaf on tyrosinase is more potent than that from Ginkgo biolaba sarcotesta.