Flavonoids as α-Glucosidase Inhibitors

Flavonoids are found ubiquitously in plants and represent ~60% of all dietary (poly)phenolic compounds. Flavonols, a sub-class of flavonoids, are present in onions, kale, apples, berries, leeks and broccoli. Some flavonols excreted in urine can be used as biomarkers of flavonol intake and are significantly associated with a lower T2D risk. Many flavonoids extracted from plants inhibit α-amylase and α-glucosidase activities in vitro, and improve postprandial glycaemia in diabetic animal models and limited human studies. Very few studies have reported on the inhibition of isomaltase, however. The disaccharide isomaltose is rarely present in nature but is commonly added as low-caloric food sweeteners in industrial-scale production, or produced from amylopectin hydrolysis to α-limit dextrins. Studies assessing the isomaltase inhibitory potential by flavonoids and acarbose are therefore of interest.