In vitro study on hypoglycaemic activity of Serbian and some European Merlot wines

Abstract

In managing Type 2 diabetes, inhibiting enzymes present in the initial stages of carbohydrate digestion, a-amylase, and a-glucosidase, could be important. Conventional inhibitors such as acarbose exhibit adverse effects, necessitating the exploration of natural products for alternative solutions. Moderate red wine consumption, rich in polyphenols, offers a biochemically supported strategy by impeding a-amylase and a-glucosidase activity. Thus, the objective of this study was to assess the in vitro a-amylase and a-glucosidase inhibitory activities of 14 Merlot wines (5 Serbian and 9 European), with a focus on elucidating the correlation between their inhibitory potency and polyphenolic profile. All samples demonstrated an inhibitory effect on both enzymes: a-amylase and a-glucosidase activities (113.6-349.5 mg equivalent acarbose/mL of wine and 1.09-12.34 mg equivalent acarbose/mL of wine, respectively), still no discernible correlation was observed between the level of inhibition and the categorization of wines based on their respective regions. The total content of polyphenols, flavonoids, tannins, and monomeric anthocyanins in examined wines showed that overall concentrations were lower in Serbian and Macedonian than in Italian and French wines. Dominant phenolic acid in all Merlot samples was gallic (10.7-134.0 mg/L), catechin was the most prevalent flavonoid (9.1-43.4 mg/L), stilbene resveratrol was also present in all samples (0.34-4.67 mg/L), while malvidin-3-O-glucoside was the most abundant anthocyanin (2.6-56.5 mg/L). Examined wines showed some specificity regarding the polyphenolic profile and could be, to some extent, differentiated primarily based on the quantitative content of polyphenols. A moderate correlation was evident between a-amylase inhibitory activity and the content of total anthocyanins and malvidin-3-O-glucoside, while notable dependence was observed between a-glucosidase inhibitory activity and the contents of total polyphenols and tannins as well as gallic acid and catechin.