银杏外种皮提取物对酪氨酸酶的抑制作用

Inhibitory mechanism of extracts from Ginkgo biolaba sarcotesta on mushroom tyrosinase

关键词:  银杏外种皮  提取方法  酪氨酸酶  抑制作用  动力学

Key words:  Ginkgo biolaba sarcotesta  extractive method  tyrosinase  inhibitory mechanism  kinetics

摘要:

以银杏外种皮为材料,采用水、乙醇和乙醇-乙醚三种不同的方法分离提取其中的活性物质(分别命名为1^#,2^#,3^#),研究它们对蘑菇酪氨酸酶催化L-多巴(L-DOPA)氧化活力的影响。结果表明,这3种提取物均对蘑菇酪氨酸酶有抑制作用,1^#,2^#和3^#对酶抑制作用的IC₅₀分别为2.25、1.75和0.32 mg/mL。抑制作用动力学结果表明:三种提取物对酶的抑制作用均表现为混合型,相应的抑制常数K_I依次为2.11、1.62和0.29 mg/mL; K_IS依次为2.80、2.33和0.45 mg/mL。结果显示,采用乙醇-乙醚提取的银杏外种皮提取物对酪氨酸酶抑制作用最强。

Abstract:

Three extractants(water,ethanol and ethanol-aether mixture)were isolated from Ginkgo biolaba sarcotesta,and then three kinds of extracts were used to test the inhibition on the activity of mushroom tyrosinase. The results showed that three extracts could inhibit the activity of tyrosinase obviously. The inhibitor's concentration leading to 50% enzyme activity lost,IC₅₀ was estimated to be 2.25,1.75 and 0.32 mg/mL,respectively. Their inhibition mechanisms were analyzed. All of three extracts showed reversibly inhibitors to tyrosinase and the type of inhibition belonged to be mixed-type. The inhibition constants,K_I and K_IS,of each extract were determined respectively and compared. The value of K_I was determined to be 2.11,1.62 and 0.29 mg/mL,respectively; the value of K_ISwas determined to be 2.80,2.33 and 0.45 mg/mL,respectively. The ethanol-aether extracts showed the best inhibition on tyrosinase.