Chemical Composition, Antioxidant and α-Glucosidase-Inhibiting Activities of the Aqueous and Hydroethanolic Extracts of Vaccinium myrtillus Leaves

Molecules. 2017 Apr 28;22(5):703. doi: 10.3390/molecules22050703.


Vaccinium myrtillus (bilberry) leaf is traditionally used in southeastern Europe for the treatment of diabetes. In the present study, the ability of bilberry leaf extracts to inhibit carbohydrate-hydrolyzing enzymes and restore glutathione concentration in Hep G2 cells subjected to glucose-induced oxidative stress was investigated. A comprehensive analysis of the antioxidant activity of two bilberry leaf extracts was performed. The aqueous extract showed excellent total antioxidant and chelating activity. Its antioxidant activity in the β-carotene-linoleic acid assay was very good, reaching the activity of the antioxidant standard BHA (93.4 ± 2.3% vs. 95.1 ± 2.4%, respectively). The hydroethanolic extract (ethanol/H₂O, 8:2, v/v), on the other hand, was a better radical scavenger and Fe2+ reducing agent. Furthermore, the aqueous extract was able to efficiently increase glutathione concentration in Hep G2 cells subjected to glucose-induced oxidative stress and restore it to the levels observed in non-hyperglycaemic cells. The hydroethanolic extract strongly inhibited α-glucosidase, with the IC50 statistically equal to the antidiabetic drug acarbose (0.29 ± 0.02 mg/mL vs. 0.50 ± 0.01 mg/mL, respectively). Phytochemical analysis revealed the presence of quercetin and kaemferol derivatives, as well as chlorogenic and p-coumaric acid. The study results indicate that V. myrtillus leaf may have promising properties as a supporting therapy for diabetes.

Keywords: Vaccinium myrtillus; antioxidant activity; glutathione; polyphenol; α-glucosidase inhibition.

MeSH terms

  • Benzothiazoles / chemistry
  • Biphenyl Compounds / chemistry
  • Ethanol / chemistry
  • Free Radical Scavengers / chemistry*
  • Free Radical Scavengers / isolation & purification
  • Free Radical Scavengers / pharmacology
  • Free Radicals / chemistry
  • Glutathione / metabolism
  • Glycoside Hydrolase Inhibitors / chemistry*
  • Glycoside Hydrolase Inhibitors / isolation & purification
  • Glycoside Hydrolase Inhibitors / pharmacology
  • Hep G2 Cells
  • Humans
  • Oxidation-Reduction
  • Oxidative Stress
  • Picrates / chemistry
  • Plant Extracts / chemistry*
  • Plant Extracts / isolation & purification
  • Plant Extracts / pharmacology
  • Plant Leaves / chemistry*
  • Solvents / chemistry
  • Sulfonic Acids / chemistry
  • Vaccinium myrtillus / chemistry*
  • Water / chemistry


  • Benzothiazoles
  • Biphenyl Compounds
  • Free Radical Scavengers
  • Free Radicals
  • Glycoside Hydrolase Inhibitors
  • Picrates
  • Plant Extracts
  • Solvents
  • Sulfonic Acids
  • Water
  • 2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid
  • Ethanol
  • 1,1-diphenyl-2-picrylhydrazyl
  • Glutathione