Evaluation of α-glucosidase inhibition potential of some flavonoids from Epimedium brevicornum
2013; Elsevier BV; Volume: 53; Issue: 2 Linguagem: Inglês
10.1016/j.lwt.2013.04.002
ISSN1096-1127
AutoresMinh Anh Thu Phan, Jin Wang, Jingyi Tang, Yan Zhi Lee, Ken Ng,
Tópico(s)Phytochemical compounds biological activities
ResumoEpimedium brevicornum leaves water extract exerted a potent and specific inhibition against yeast α-glucosidase, with 50% inhibition of activity (IC50) at 11.8 μmol/L (or 2.01 μg) Gallic Acid Equivalent (GAE)/mL. Several major flavonols from the leaves were evaluated for inhibitory activity. Baohuoside I exhibited strong inhibition against the α-glucosidase while icariin and epimedin A, B and C were weak or inactive. All compounds were inactive against pancreatic α-amylase. The IC50 of baohuoside I was 28.9 μmol/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 μmol/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′-OH and C7-OH, showed weak inhibition while baohuoside I, which has no free C4′-OH but free C7-OH, showed strong inhibition, indicates the primary importance of the A-ring C7-OH for α-glucosidase inhibitory activity.
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