Non-targeted metabolomics reveals tissue-specific metabolic profiling and antioxidant - related markers in Mosla chinensis Maxim. cv. Jiangxiangru

<i>Mosla chinensis</i> Maxim. cv. Jiangxiangru (McJXR) is an aromatic medicinal plant, but its tissue-specific metabolites and antioxidant capacity lack systematic characterization. This study utilized non-targeted metabolomics to comprehensively characterize the metabolic profiles of the stem, leaf, and flower tissues of McJXR, and to assess their <i>in vitro</i> antioxidant activities. A total of 87 compounds were identified by GC-MS, among which 12, 6, and 8 were uniquely present in the flower, stem, and leaf, respectively. LC-MS/MS detected 21,636 and 21,880 ion features in positive and negative ion modes, respectively, revealing a distinct tissue-specific distribution of metabolites, with 176, 169 and 154 metabolites identified in the flower, stem and leaf, respectively. The OPLS-DA model (positive ion mode: R²X = 0.684, Q² = 0.962) further confirmed the reliability of metabolic profile differences across tissues. The differential metabolites (DMs) were primarily enriched in the ABC transporter pathway and the biosynthesis pathways of plant secondary metabolites. Antioxidant activity followed the order: flower > leaf > stem. Total flavonoid content (TFC, reaching up to 10.82 mg RE/g DW in the flower) and total phenolic content (TPC, peaking at 99.25 mg GAE/g DW in the leaf) exhibited significant positive correlations with antioxidant capacity (r > 0.5, p < 0.05), with TFC showing a stronger correlation (r = 0.9443 with the ABTS assay, p < 0.01). Mantel test results identified octopamine, 4-aminobutyric acid, and xylitol as potential antioxidant-related metabolites. This study elucidated the tissue-specific distribution patterns of McJXR metabolites and the biochemical basis of their antioxidant activity, providing a scientific foundation for the rational selection of medicinal parts and the development of functional constituents.