An analytical pipeline to compare and characterise the anthocyanin antioxidant activities of purple sweet potato cultivars

•Thirty purple sweet potato cultivars were analysed quantitatively and qualitatively.•Four complementary methods were applied to evaluate antioxidant activities.•The fingerprint–efficacy relationship was investigated by grey relational analysis.•Seven identified anthocyanins were considered as key constituents of the bioactivity.•A potential platform for cultivar selection and plant breeding was established. Purple sweet potato (Ipomoea batatas L.) is rich in anthocyanin pigments, which are valuable constituents of the human diet. Techniques to identify and quantify anthocyanins and their antioxidant potential are desirable for cultivar selection and breeding. In this study, we performed a quantitative and qualitative chemical analysis of 30 purple sweet potato (PSP) cultivars, using various assays to measure reducing power radical-scavenging activities, and linoleic acid autoxidation inhibition activity. Grey relational analysis (GRA) was applied to establish relationships between the antioxidant activities and the chemical fingerprints, in order to identify key bioactive compounds. The results indicated that four peonidin-based anthocyanins and three cyanidin-based anthocyanins make significant contributions to antioxidant activity. We conclude that the analytical pipeline described here represents an effective method to evaluate the antioxidant potential of, and the contributing compounds present in, PSP cultivars. This approach may be used to guide future breeding strategies.