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 combination 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 by which quercetin and rutin ameliorate degenerative conditions. The effect of the flavonoids on α-amylase and α-glucosidase activities and pro-oxidant induced lipid peroxidation in rats pancreas homogenates were investigated, as well as the antioxidant activities as the radicals [1,1-diphenyl-2-picrylhydraxyl (DPPH), nitric oxide (NO), hydroxyl (OH)] scavenging and Fe2+-chelating abilities. Rutin had a significantly higher DPPH* (EC50 = 0.264μM), ABTS* (7.1μmol.TEAC/100g), OH* (EC50 = 0.065μM) and NO* (EC50 = 0.101μM) scavenging abilities than quercetin [DPPH (EC50 = 0.349μM), ABTS (4.7μmol.TEAC/100g), OH* radicals (EC50 = 0.098μM), NO* (EC50 = 0.119μM)]. Similarly, rutin (EC50 = 0.048μΜ) also exhibited a significantly (P<0.05) higher inhibition of Fe2+ - induced lipid peroxidation than qucercetin (EC50 = 0.075μΜ). Furthermore, rutin had a stronger inhibition of α-amylase (IC50 = 0.043μM) and α-glucosidase (IC50 = 0.037μM) activities than quercetin [α-amylase (IC50 = 0.061μM); α-glucosidase (IC50 0.038μM)]. A combination of Quercetin and Rutin (1:3) showed the strongest inhibition (P<0.05) of α-amylase activity (IC50 = 313.87μg/L) while Quercetin showed the least inhibition of α-amylase (IC50 507.61μg/L) activity. Quercetin also had the least inhibition of α-glucosidase activity (IC50 346.78μg/L), while a combination of Quercetin and Rutin (1:3) showed the highest inhibitory ability (IC50 254.45μg/L). This study revealed that rutin had a higher inhibitory ability on key enzymes linked to type-2 diabetes (α-amylase and α-glucosidase) than quercetin. Furthermore, a combination of quercetin and rutin (1:3) had highest inhibitory abilities against the enzymes.