engleski

Inhibition of alfa-glucosidase by polyphenols present in traditional, indigenous apple varieties

This work aimed to evaluate polyphenols from two traditional apple varieties as - glucosidase inhibitors. Polyphenols were extracted from the flesh and skin of two traditional apple varieties (Božićnica and Batulenka) by using ultrasonic- assisted extraction. Total polyphenols in extracts were determined by the spectrophotometric Folin- Ciocalteu method, expressed as gallic acid equivalents (GAE). The α-glucosidase activity was evaluated based on the spectrophotometric determination of p-nitrophenol (pNP) released from pnitrophenyl-α-D-glucopyranoside (p-NPG) substrate by the action of the enzyme. To inhibit enzyme activity, various polyphenol concentrations were added into the reaction mixture. IC50 value was calculated (concentration of polyphenols that gives 50% inhibition). Božićnica and Batulenka contained 337.24 and 202.17 mg GAE kg-1 in the flesh and 2132.91 and 824.43 mg GAE kg-1 in the peel, respectively. Polyphenols inhibited - glucosidase activity and inhibition reached a steady state. IC50 values, expressed as μg of gallic acid equivalents (GAE) per mL of reaction solution, of the flesh of Batulenka and Božićnica were 1.69 and 1.47, respectively. Peel showed similar IC50 values (1.07, and 0.33 μg GAE cm-3, for the peel of Batulenka and Božićnica, respectively). These results suggest that polyphenols from the flesh and skin of traditional apple varieties are potent inhibitors of α- glucosidase activity.

α-glucosidase ; inbition ; polyphenols ; apple

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