Antioxidant activity of polyphenol rich fruits on human erythrocytes
Diets rich in fruit and vegetables promote health and delay the onset of diseases associated with oxidative stress. The benefit, especially of different berries, has been largely attributed to their content of numerous phytochemicals, and their effects in terms of antioxidant capacity are often evaluated chemically by different methods. We have instead used a highly relevant biological model, a modified CAP-e assay (Cell-based Antioxidant Protection in erythrocytes), to evaluate bioefficacy of antioxidants in Swedish berries. Extracts of twelve fruit and berries were analysed both by chemical and biological analyses: apple (Malus domestica, peel), bilberry (Vaccinium myrtillus), black currant (Ribes nigrum), purple chokeberry (Aronia x prunifolia), cranberry (Vaccinium macrocarpon), elderberry (Sambucus nigra), lingonberry (Vaccinium vitis-idaea), raspberry (Rubus idaeus), rose hips (Rosa spp.), sea buckthorn (Hippohae rhamnoides), sloe (Prunus spinosa) and strawberry (Fragaria x ananassa). Purple chokeberry, sloe and rose hips showed high antioxidant capacity in the chemical assays. Rose hips showed the highest degree of antioxidant protection also in the biological model, however, chokeberry and sloe showed medium or low protection. Furthermore, strawberry showed overall high protection in the biological assay but low antioxidant capacity in the chemical assays. The chemical and biological models showed different results and future studies of the biological model and in vivo situations are necessary.