Antioxidant assessment of an anthocyanin-enriched blackberry extract

Gel filtration of black berry (Rubus fruticosus sp) ethanolic extracts was employed to obtain an anthocyanin-enriched extract. The anthocyanin profile identified cyanidin-3-glucoside as the primary (e.g., 90% of total) anthocyanin present in blackberry. Gel filtration of crude extracts resulted in a 20-fold increase in total anthocyanin content, with no change in the proportion of cyanidin-3-glucoside. Antioxidant activities of both the crude and anthocyanin-enriched blackberry extracts were determined using cell-free (ORAC) and cell-based (INT-407 intracellular) antioxidant assays. Antioxidant activity, assessed by the ORAC assay, indicated a 7-fold increase in activity for the anthocyanin-enriched fraction. Similar results were obtained for the anthocyanin-enriched extract using the intracellular antioxidant assay with INT-407 cells. Our results indicate that the anthocyanin content, and more specifically the presence of cyanidin-3-glucoside, in blackberry, contributes a major part of the antioxidant ability to suppress both peroxyl radical-induced chemical and intracellular oxidation.