Pomegranate ellagitannins inhibit α-glucosidase activity under simulated gastro-intestinal conditions

Pomegranate extract was tested for its ability to inhibit α-amylase and α-glucosidase activity.

RESEARCH TITLE: Pomegranate ellagitannins inhibit α-glucosidase activity in vitro and reduce starch digestibility under simulated gastro-intestinal conditions

COUNTRIES: Italy

CONDUCTED BY: Universitá degli Studi di Modena e Reggio Emilia

PUBLISHED ON: International Journal of Food Sciences and Nutrition

RESEACH:

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 (IC₅₀ 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.

YEAR: 2015