Comparative effect of quercetin and rutin on α-amylase, α-glucosidase, and some pro-oxidant-induced lipid peroxidation in rat pancreas

Abstract

This study was designed to investigate the effect of quercetin, its glycosylated conjugate rutin and various combinations of the two flavonoids on carbohydrate-hydrolyzing enzymes associated with type 2 diabetes (α-amylase and α-glucosidase) in a bid to understand the possible mechanisms of action by which quercetin and rutin could be used in the prevention/management of the degenerative condition. The aim of this study is to investigate the effect of quercetin, rutin, and various combinations of the two flavonoids on α-amylase and α-glucosidase activities and the ability of the flavonoids to inhibit some pro-oxidants-induced lipid peroxidation in rat pancreas. The effect of the flavonoids on α-amylase and α-glucosidase activities as well as pro-oxidant (Fe2+ and SNP)-induced lipid peroxidation in rats’ pancreas homogenates was investigated. Rutin (IC50 = 0.048 μΜ) exhibited a significantly (P < 0.05) higher inhibition of Fe2+-induced lipid peroxidation than quercetin (IC50 = 0.075 μΜ). Furthermore, rutin had a stronger inhibition of α-amylase (IC50 = 0.043 μM) and α-glucosidase (IC50 = 0.037 μM) activities than quercetin [α-amylase (IC50 = 0.061 μM); α-glucosidase (IC50 0.038 μM)]. A combination of 25 % quercetin and 75 % rutin showed the strongest inhibition (P < 0.05) of α-amylase activity (IC50 = 313.87 μg/L) while 100 % quercetin showed the least inhibition of α-amylase (IC50 507.61 μg/L) activity and same trend was followed for α-glucosidase activity. This study revealed that glycosylation increased the inhibitory ability of quercetin on key enzymes linked to type 2 diabetes (α-amylase and α-glucosidase), and combination of quercetin and rutin had higher synergistic inhibitory abilities on the enzymes than the individual flavonoids, suggesting that a combination of food sources rich in these flavonoids could be very effective in the management/prevention of type 2 diabetes.