Organ-Dependent Comparative Metabolomic Profiling of Actinidia arguta Using LC–QTOF–MS Reveals Enrichment of Condensed Tannins in Roots

Actinidia arguta is a valuable plant resource known for its diverse bioactive constituents. However, organ-dependent metabolic variation remains insufficiently explored. In this study, an integrated approach combining LC–QTOF–MS-based metabolomic profiling, multivariate analysis, and phytochemical isolation was employed to investigate metabolic differences among fruits, leaves, and roots of A. arguta. Comparative LC–QTOF–MS profiling and principal component analysis (PCA) revealed clear organ-specific metabolic differentiation. The root extract formed a distinct cluster, primarily characterized by flavan-3-ol oligomers, including procyanidin dimers and a trimer. Targeted isolation and spectroscopic analysis identified these compounds as major constituents of the root. Quantitative analysis showed that the root exhibited the highest antioxidant activity (60.8 ± 6.2%) and total phenolic content (10.8 ± 0.7 mg GAE/g dried weight), followed by leaves and fruits, indicating significant organ-dependent variation. The enhanced antioxidant activity observed in the root extract was consistent with the enrichment of oligomeric procyanidins, which are known for their strong radical-scavenging capacity. These findings demonstrate pronounced organ-specific metabolic specialization in A. arguta, with the root characterized by a condensed tannin–dominant chemical profile. This study highlights the potential of root-derived procyanidins as bioactive natural products and provides a basis for their utilization in functional and phytochemical applications, as well as insights into plant defense-related metabolism.