The chemical composition, antioxidant activity and α-glucosidase inhibitory activity of water-extractable polysaccharide conjugates from northern Manitoba lingonberry

Lingonberry (Vaccinium vitis-idaea L.) is a small northern fruit that has been harvested historically by native North Americans and Northern Europeans. These berries have been traditionally consumed as food and for medicinal use. Lingonberries are reported to be rich in vitamin C, benzoic acid, and anthocyanins, which have been implicated in health benefits associated with the consumption of lingonberries. We hypothesized that water-extractable polysaccharides, conjugated with proteins and/or phenolics may also serve as bioactive compounds with potential health benefits in northern Manitoba lingonberries. A hot water extraction was used to obtain water-extractable polysaccharides from lingonberries and the water-extractable polysaccharides were fractionated into water-eluted/neutral and NaCl-eluted/acidic fractions using chromatography. The water-extractable polysaccharides were evaluated for their chemical composition and structural features. The antioxidant activity (FRAP and ABTS assays) and potential of the polysaccharides to serve as α-glucosidase inhibitors were determined. The chemical composition and structural features of the water-extractable polysaccharides were influenced by fraction. The water-extractable polysaccharides and fractions all possessed antioxidant activity, while only the water-extractable polysaccharide conjugates and NaCl-eluted/acidic fraction demonstrated appreciable α-glucosidase inhibition. This work provides novel information indicating that water-extractable polysaccharide conjugates isolated from northern Manitoba lingonberry demonstrate bioactivity.