Variety-Specific Polyphenol Accumulation and Antioxidant Activity Differences in Apple Fruits

Oxidative stress is a key inducer of chronic diseases, and apple polyphenols exhibit significant antioxidant potential. This study systematically analyzed polyphenol accumulation characteristics and antioxidant activity of four apple cultivars (Qincui, Jiuyue Qiji, Orin, Ruixue) using a multi-level system of traditional biochemistry, cell experiments, and untargeted metabolomics. Results showed Ruixue had the highest soluble solids, soluble sugar, total phenol contents, and DPPH scavenging activity, while Jiuyue Qiji was rich in total flavonoids. Apple polyphenols alleviated D-gal-induced BV2 cell senescence, with Ruixue and Jiuyue Qiji showing the strongest protective effects. Metabolomics identified 207 polyphenols, and 87 core active polyphenols significantly correlated with antioxidant activity were screened. Ruixue exhibited distinct polyphenol enrichment. This study clarifies cultivar-specific polyphenol accumulation and core active components, providing theoretical basis for high-antioxidant apple breeding and functional product development.