title: Pomegranate ellagitannins inhibit α-glucosidase activity in vitro and reduce starch digestibility under simulated gastro-intestinal conditions.
abstract: Pomegranate extract was tested for its ability to inhibit α-amylase and α-glucosidase activity. Pomegranate extract strongly inhibited rat intestinal α-glucosidase in vitro whereas it was a weak inhibitor of porcine α-amylase. The inhibitory activity was recovered in an ellagitannins-enriched fraction and punicalagin, punicalin, and ellagic acid were identified as α-glucosidase inhibitors (IC(50) of 140.2, 191.4, and 380.9 μmol/L, respectively). Kinetic analysis suggested that the pomegranate extract and ellagitannins inhibited α-glucosidase activity in a mixed mode. The inhibitory activity was demonstrated using an in vitro digestion system, mimicking the physiological gastro-intestinal condition, and potatoes as food rich in starch. Pre-incubation between ellagitannins and α-glucosidase increased the inhibitory activity, suggesting that they acted by binding to α-glucosidase. During digestion punicalin and punicalagin concentration decreased. Despite this loss, the pomegranate extract retained high inhibitory activity. This study suggests that pomegranate ellagitannins may inhibit α-glucosidase activity in vitro possibly affecting in vivo starch digestion.
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia , Reggio Emilia , Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bellesia
authors.forename: Elena
authors.initials: E
authors.lastname: Verzelloni
authors.forename: Davide
authors.initials: D
authors.lastname: Tagliazucchi
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D041981:Gastrointestinal Tract / Q000187:drug effects* / Q000378:metabolism; D047348:Hydrolyzable Tannins / Q000494:pharmacology*; D029561:Lythraceae / Q000737:chemistry*; D008954:Models, Biological; D010936:Plant Extracts / Q000032:analysis / Q000494:pharmacology*; D059808:Polyphenols / Q000032:analysis / Q000494:pharmacology; D051381:Rats; D013213:Starch / Q000737:chemistry; D053719:Tandem Mass Spectrometry; D000520:alpha-Glucosidases / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D047348:Hydrolyzable Tannins; D010936:Plant Extracts; D059808:Polyphenols; C013515:ellagitannin; D013213:Starch; D000520:alpha-Glucosidases
keywords: Diabetes; ellagitannins; mass spectrometry; pomegranate; starch digestion