Evaluation of ¦Á-glucosidase inhibition potential of some flavonoids from?Epimedium brevicornum

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• 作者：Minh Anh Thu Phan ; Jin Wang ; Jingyi Tang ; Yan Zhi Lee ; Ken Ng ; ^{ngkf@unimelb.edu.au}
• 关键词：¦Á-Glucosidase inhibitors ; ¦Á-Amylase inhibitors ; Epimedium ; Diabetes
• 刊名：Lebensmittel-Wissenschaft und -Technologie
• 出版年：2013
• 出版时间：October, 2013
• 年：2013
• 卷：53
• 期：2
• 页码：492-498
• 全文大小：735 K

文摘

Epimedium brevicornum leaves water extract exerted a potent and specific inhibition against yeast ¦Á-glucosidase, with 50 % inhibition of activity (IC50) at 11.8?¦Ìmol/L (or 2.01?¦Ìg) Gallic Acid Equivalent (GAE)/mL. Several major flavonols from the leaves were evaluated for inhibitory activity. Baohuoside I exhibited strong inhibition against the ¦Á-glucosidase while icariin and epimedin A, B and C were weak or inactive. All compounds were inactive against pancreatic ¦Á-amylase. The IC50 of baohuoside I was 28.9?¦Ìmol/L and its kinetic mode of inhibition was of the mixed type inhibition, with K₁ (inhibition constant for the formation of the baohuoside-enzyme complex) and K₂ (inhibition constant for the formation of the baohuoside-enzyme-substrate complex) of 12.4 and 31.7?¦Ìmol/L, respectively. Since its K₁ was lower than its K₂, it would indicate that baohuoside I tends to bind more easily and firmly to the free enzyme than to the enzyme-substrate complex. The fact that icariin, which has no free C4¡ä-OH and C7-OH, showed weak inhibition while baohuoside I, which has no free C4¡ä-OH but free C7-OH, showed strong inhibition, indicates the primary importance of the A-ring C7-OH for ¦Á-glucosidase inhibitory activity.