Polyphenol content and antioxidant activity of wild and cultivated blackberry (Rubus Fruticosus L.) juices

Blackberry fruits (Rubus fruticosus L.) have been valued as an excellent source of polyphenol content and antioxidant activity. In this study, blackberry juices of two cultivated blackberry cultivars and two wild blackberry cultivars were evaluated as potential sources of polyphenolic compounds and antioxidant activity. The content of polyphenols (total polyphenols, total flavonoids, flavonols, total and monomeric anthocyanins) and antioxidant activity (DPPH, ABTS, and OH radicals tests) were determined by the spectrophotometric method. The juices of wild blackberry varieties indicated the higher content of total polyphenols (2.16 - 2.25 mg GAE/g fw (fresh weight)), total anthocyanins (0.83 - 1.34 mg CyGE/g fw), and monomeric anthocyanins (0.70 - 1.14 mg CyGE/g fw), while the juice of cultivated blackberry variety had higher content of flavonoids (0.45 mg QcE/g fw) and flavonols (0.68 mg QcE/g fw). The results of the DPPH and the ABTS tests showed that the juices of wild blackberries possessed higher antioxidant activity compared to cultivated blackberries (p < 0.05). All blackberry juices showed high concentrations of total polyphenols, including flavonoids, and anthocyanins content. The antioxidant activities of wild variety samples were stronger than of cultivated varieties. Significant correlations were determined between the content of total polyphenols, total and monomeric anthocyanins and the capacities of inhibition DPPH and ABTS radicals.