INHIBITION EFFECT OF BULGARIAN LINGONBERRY (VACCINIUM VITIS-IDAEA L.) EXTRACTS ON α-AMYLASE ACTIVITY

Lingonberry fruits are known to be a rich source of natural compounds which provide many health benefits. Polyphenol-rich extracts from lingonberries were tested for their ability to inhibit alpha-amylase. The inhibitory activity of dietary polyphenols in lingonberry extracts towards alpha-amylase offers the possibility to modulate the absorption of sugars, leading to benefits for type 2 diabetic patients and those with metabolic syndrome. Inhibiting properties of Vaccinium vitis-idaea fruits growing in Bulgaria against carbohydrate enzyme were reported for the first time in this study. The contents of phenolic acids, flavonols and stilbenes were determined by HPLC analysis. Quercetin derivates as myricetin and rutinoside were the major quantified flavonols. The results revealed that lingonberry extracts are effective inhibitors of alpha-amylase with IC50 values from 34.2 to 69.9 mu g GAE/ml. The extent of alpha-amylase inhibition was related to their total anthocyanin, myricetin, resveratrol and chlorogenic acid contents. The most effective in inhibiting alpha-amylase extract contains appreciable amounts of myricetin, rutin, resveratrol, chlorogenic acid and the highest value of total anthocyanins. All the samples proved to have antioxidant activity measured by two different in vitro assays (FRAP and CUPRAC).