Phytochemical composition and biological activity of bilberry fruit juice (Vaccinium myrtillus L.) from Bulgaria

This study examined the polyphenol composition, antioxidant properties, and biological activity of bilberry ( Vaccinium myrtillus L.) fruit juice from Bulgaria. Antioxidant potential was analyzed using ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), DPPH (2,2-diphenyl-1-picrylhydrazyl), and FRAP (ferric reducing antioxidant power) methods. Total polyphenol, flavonoid, and anthocyanin contents were measured using colorimetric methods. Specific anthocyanin content was measured by UPLC-MS/MS. Cytoprotective and superoxide anion radical-scavenging activities were analyzed in in vitro Saccharomyces cerevisiae experiments. UPLC-MS/MS analysis revealed a total anthocyanin content of 338.5 mg/100 g fresh fruits, and the dominant compounds were malvidins (38.1%), delphinidins (33.2%), petunidins (18.6%), and cyanidins (10.1%). Total polyphenol content was 8.40 ± 0.29 mg GAE/100 mL, and total flavonoid content was 7.26 ± 0.11 mg QE/100 mL. Antioxidant potential was as follows: ABTS (3.6 ± 0.08 mM UAE), DPPH (89 ± 2.1%), and FRAP (2.4 ± 0.09 mM Fe(II)/L). Cell-based assays demonstrated significant cytoprotective activity and reduced methyl methanesulfonate-induced superoxide anions. These results demonstrate the value of Bulgarian bilberry juice as a source of bioactive compounds and as a potential raw material for the pharmaceutical and nutritional industries.