Extraction of Bilberry (Vaccinium myrtillus) Antioxidants using Supercritical/Subcritical CO2 and Ethanol as Co-Solvent

Anthocyanins and other phenolic compounds of bilberry (Vaccinium myrtillus) are known for their antioxidant properties. Supercritical (SC) and Subcritical (SubC) CO2 extractions have been used to improve extraction and selectivity of plant bioactive compounds. Bilberry was extracted by SC CO2 followed by SubC CO2 with 10% v/v ethanol as co-solvent. Total phenolic compounds, anthocyanins and proanthocyanidins were quantified and chemically characterized by HPLC-DAD-ESI-MS/MS. Antioxidant activity was tested by reducing power assay, free radical scavenging activity (DPPH) and ABTS radical cation assay. SubC CO2 selectively extracted cyanidin-3-O-glucoside and cyanidin-3-O-arabinoside. Delphinidin-3-O-glucoside, ellagic acid pentoside, feruloyl hexoside and several quercetin glycosides were also extracted. SubC CO2 extracts showed a high antioxidant activity [DPPH IC50 = 102.66 (±2.64); ABTS IC50 = 8.49 (±0.41) and reducing power activity IC50 = 10.30 (±0.10)]. SubC-CO2 extraction of bilberry is an efficient method to recover selectively compounds with a high antioxidant activity and a high potential for pharmacological applications.