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.