Inhibitory effects of anthocyanins on α-glucosidase activity

Anthocyanins are plant pigments widely present in fruits and vegetables that exert health benefits as part of human diet. They exist in not glycosylated forms (anthocyanidins) and glycosylated forms. Anthocyanins have been studied for their ability to inhibit polysaccharide metabolism enzymes (such as alpha-glucosidase) and, therefore, attenuate hyperglycemia and modulate type II diabetes. The aim of the present work was to compare the inhibitory activity of anthocyanins with that of acarbose, a common alpha-glucosidase inhibitor, by evaluating IC50 and K-m, to compare the inhibitory capabilities among different compounds in an in vitro study. Our results showed that most of the anthocyanins studied presented lower IC50 values than acarbose; only Pn-3-glc presented IC50 value close to acarbose. Moreover, there was no difference in K-m between complete competitive and complete non-competitive types of inhibition (T-test, p > 0.05). In conclusion, the anthocyanins and their degradation products work together on attenuating abilities of this sugar metabolism key enzyme, throughout competitive and non-competitive modes.