Determinants of antioxidant capacity in tree peony (Paeonia suffruticosa) petals: Color, active substances, oxidase activity, and in vitro antioxidant activity

• Tree peonies are divided into purple, pink purple and pink white groups for clear result analysis. • DPPH radical scavenging ability and superoxide dismutase activity had significant positive effects on antioxidant ability. • Significant differences in bioactive components and antioxidant capacity exist among tree peony cultivars. • This research adopts comprehensive analytical methods including color classification, correlation analysis and principal component analysis. • This study provides sufficient scientific evidence for the development of peony-based food, medicines and cosmetics.