Characterization of Antioxidant Constituents and Geographical Differentiation of Polygonum multiflorum Thunb. Leaves...

This study established an activity-oriented analysis method based on offline two-dimensional liquid chromatography-electrochemical detection (2D-LC-ECD) combined with ultra-high-performance liquid chromatography-Orbitrap-MS/MS (UHPLC-Orbitrap-MS/MS), which was used to comprehensively characterize the antioxidant components of Polygonum multiflorum Thunb. leaves (PML) and screen for differential compounds in samples from different origins. Antioxidant components were screened using 2D-LC-ECD combined with in vitro radical scavenging experiments; structure identification was conducted via UHPLC-Orbitrap-MS/MS, and chemometric analysis alongside quantitative determination of 19 major components was carried out across 31 batches of samples. A total of 43 potential antioxidant compounds were identified from PML, including 11 phenolic acids, 29 flavonoids, 2 stilbene glycosides, and 1 amino acid; phenolic acids and their derivatives, along with flavonoids, were identified as major contributors to antioxidant activity. Hierarchical clustering analysis and principal component analysis both grouped samples into four categories by origin; the orthogonal partial least squares discriminant analysis model (R²X = 0.933, R²Y = 0.941, Q² = 0.846) screened 10 key markers (VIP > 1). The quantitative results showed that polygonacetophenoside had the highest content in PML. In summary, the 2D-LC-ECD coupled with LC-Orbitrap-MS/MS strategy confirmed that phenolic acids and flavonoids are the core material basis for PML's antioxidant capacity, providing scientific evidence for the industrial development of PML as a natural antioxidant.