Scavenging Capacity of Berry Crops on Superoxide Radicals, Hydrogen Peroxide, Hydroxyl Radicals, and Singlet Oxygen

The antioxidant activities against superoxide radicals (O2•-), hydrogen peroxide (H2O2), hydroxyl radicals (OH•), and singlet oxygen ('O2) was evaluated in fruit juice from different cultivars of thornless blackberries (Rubus sp.), blueberries (Vaccinium spp.), cranberries (Vaccinium macrocarpon Aiton), raspberries (Rubus idaeus L. and Rubus occidentalis L.), and strawberries (Fragaria x ananassa Duch.). Among the different cultivars, juice of 'Hull Thornless' blackberry, 'Earliglow' strawberry, 'Early Black' cranberry, 'Jewel' raspberry, and 'Elliot' blueberry had the highest antioxidant capacity against superoxide radicals (O2•-), hydrogen peroxide (H2O2), hydroxyl radicals (OH•), and singlet oxygen ('O2). In general, blackberries had the highest antioxidant capacity inhibition of O2•-, H2O2, and OH•. Strawberry was second best in the antioxidant capacity assay for these same free radicals. With regard to 'O2 scavenging activity, strawberry had the highest value, while blackberry was second. Cranberries had the lowest inhibition of H2O2 activity. Meanwhile, blueberries had the lowest antioxidant capacity against OH• and 'O2. There were interesting and marked differences among the different antioxidants in their abilities to scavenge different reactive oxygen species. β-Carotene had by far the highest scavenging activity against 'O2 but had absolutely no effect on H2O2. Ascorbic acid was the best at inhibiting H2O2 free radical activity. For OH•, there was a wide range of scavenging capacities from a high of 15.3% with α-tocopherol to a low of 0.88% with ascorbic acid. Glutathione had higher O2•- scavenging capacity compared to the other antioxidants. Keywords: Active oxygen species; superoxide radicals; hydrogen peroxide; hydroxyl radicals; singlet oxygen; berry crops