Dietary Polyphenols as Natural Inhibitors of α-Amylase and α-Glucosidase

It is well known that carbohydrates are the main source of calories in most diets. However, by inhibiting carbohydrases, intake of calories is reduced and weight loss is improved. alpha-amylase is an enzyme that hydrolyses alpha-1,4 glycosidic linkages of alpha-linked polysaccharides, resulting in low-molecular-weight products such as glucose, maltose and maltotriose, while alpha-glucosidase catalyzes the hydrolysis of nonreducing alpha-1,4-linked glucose moieties from disaccharides or oligosaccharides. Currently, one of the most common nutritional disorders in the world is hyperglycemia. One of the new therapeutic approaches to treat this disease is the application of natural inhibitors, such as polyphenols, that control starch digestion and regulate blood glucose level. Dietary polyphenols showed potential inhibitory activity against alpha-amylase and alpha-glucosidase and this review summarizes the recently published literature that studied inhibition mechanisms and the structure-activity relationship between individual dietary polyphenols and mentioned digestive enzymes. It is known that higher binding interactions cause higher inhibitory activities; thus, different polyphenols can affect different steps in the digestion of polysaccharides. The aim of this review is to clarify these mechanisms and to introduce polyphenol-rich functional foods as potential tools for the inhibition of alpha-amylase and alpha-glucosidase.