Antidiabetic and Antioxidant Properties of Bilberry (Vaccinium myrtillus Linn.) Fruit and Their Chemical Composition

Bilberry [Vaccinium myrtillus Linn. (Ericaceae)] fruit (VMF) has been traditionally used for treatment of bladder stones, biliary disorders, scurvy, coughs, and lung tuberculosis. VMF may have some pharmaceutical properties owing to these uses, but in vivo and in vitro studies are limited for clarification of medicinal activity and its antidiabetic and antioxidant properties are not investigated in detail. Anti-amylase, anti-glucosidase, and antioxidant activities of methanol (ME), ethanol (EE), acetone (AE), and water (WE) extracts of VMF were investigated. In addition, some chemical compositions were determined by using spectrophotometric methods. Antidiabetic and antioxidant activities of extracts were studied by using different tests such as α-amylase and α-glucosidase inhibitory, total antioxidant, DPPH scavenging activities according to in vitro methods at different concentrations (10-250 μg mL-1). Compared with the standards, ME, WE, and EE showed strong total antioxidant activities with IC50 (μg/mL) values of 24.46±0.34, 25.24±0.78, and 27.48±0.60, respectively. At the same time, ME (IC50 61.38±1.40 μg mL-1) and EE (IC50 65.52±1.19 μg mL-1) demonstrated very effective inhibitory activity against α-amylase and moderate inhibitory activity against α-glucosidase. All extracts also showed high reducing power, metal chelating activity, superoxide anion, DPPH radical, and H2O2 scavenging activities. Important relationships were found between biological activity and chemical composition by statistical analyses. The VMF can be used as an antidiabetic and antioxidant source in medicinal and pharmaceutical areas due to its chemical composition. Anthocyanin contents may influence the anti-amylase inhibition activity more than phenolic and flavonoid contents.