Phenolic Compound Content and the Antioxidant and Antimicrobial Activity of Wild Blueberries (Vaccinium stenophyllum Steud.) Fruits Extracts during Ripening

The genus Vaccinium contains about 400 species distributed worldwide, but only a few species and varieties have had their phenolic composition and biological activity documented. In this study, phenols, flavonoids, anthocyanins, antioxidant and antimicrobial activity of methanolic extracts of Vaccinium stenophyllum Steud. fruits: 1-totally immature, 2-immature, 3-immature/close to maturity and 4-mature, were determined using UV-Visible spectrometry and HPTLC. The totally immature fruit extract showed the highest content of total phenols (19.153 +/- 0.175 mg GAE/g DW), chlorogenic acid (20.867 +/- 0.240 mg CAE/g DW), and the highest antioxidant activity by ABTS(?+) (196.761 +/- 0.641 mu M TE/g DW) and DPPH? (146.580 +/- 6.466 mu M TE/g DW). Immature, immature/close to maturity and mature fruits extracts, exhibited the lowest MIC (9.37 mg/mL) and MBC (18.75 mg/mL) against Escherichia coli, Salmonella choleraesuis, and Shigella flexneri. The mature fruits extract exhibited the highest content of total anthocyanins (0.141 +/- 0.004 mg CE/g DW) and cyanidin-3-glucoside (19.230 +/- 0.309 mg CGE/g DW). The content of phenols, flavonoids and anthocyanins was higher than that reported for other Vaccinium species. These results showed the relevance of Vaccinium stenophyllum Steud. for breeding purposes to enhance the bioactivity of cultivars, or as a source of natural additives for the food industry, among others.