Spatiotemporal Accumulation of Four Major Bioactive Compounds in Zanthoxylum nitidum Roots: Implications for...

This study investigated the spatial distribution and age-dependent accumulation of major bioactive compounds in cultivated Zanthoxylum nitidum roots to optimize harvesting strategies and quality evaluation. The root bark (RB) radial proportion increased during early growth stages, peaking at 16.67% in five-year-old plants. All four compounds exhibited pronounced tissue specificity, preferentially accumulating in RB, whereas root wood (RW), accounting for 83.33-93.67% of total root radial proportion, maintained low concentrations. The accumulation patterns of individual compounds varied markedly with growth age: nitidine chloride (NC) and chelerythrine (CHE) reached their highest concentrations in three-year-old RB (0.89% and 2.22%), magnoflorine (MAG) showed a bimodal pattern with peaks in the first and fifth years, and hesperidin (HES) displayed a distinct V-shaped trend. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) consistently demonstrated that tissue type was the primary source of variation in chemical composition, whereas age-related differences within RB were mainly associated with HES, NC, and CHE. These findings provide valuable preliminary guidance on tissue-specific accumulation and structural development, offering a framework for refining harvesting strategies and quality evaluation.