Multimodal Analytical Platform Coupled With Biological Assays Unravels Tissue-Specific Chemical Profiles, Spatial Metabolite Distributions and Bioactivities of Root Xylem and Root Bark of Tripterygium wilfordii.

Characterising chemical and biological differences among different tissues of medicinal plants is important for understanding their tissue-specific characteristics and medicinal efficacy. The root xylem (RX) and root bark (RB) of Tripterygium wilfordii have historically been used differently; however, the basis underlying their differential utilisation remains insufficiently characterised. In this study, complementary analytical measurements were integrated to compare the chemical and biological differences between the two root tissues across multiple dimensions. Ion fingerprinting revealed substantial overlap in the detected chemical features, with 81.09% of the ion features in the RX also detectable in the RB. Despite this high proportion of shared constituents, multivariate statistical analysis clearly separated the RX and RB, indicating significant differences in their overall ion abundance patterns. Mass spectrometry imaging further resolved tissue-specific distribution patterns, showing that alkaloids were mainly localised in the phloem, triterpenoids were enriched in the periderm, whereas diterpenoids exhibited broader distributions across the root tissues. Targeted quantitative analysis provided direct evidence for the differential abundance of metabolites, showing that multiple bioactive constituents, including triptolide, triptonide and celastrol, were present at considerably higher levels in the RB than in the RX. Biological evaluation further demonstrated that, compared with the RX, the RB exhibited stronger inhibition of lipopolysaccharide-induced nitric oxide production, albeit with higher cytotoxicity. Taken together, the complementary measurements confirmed that, although the RX and RB share a large number of chemical features, they differ markedly in overall metabolite abundance and spatial distribution, ultimately exhibiting distinct biological responses. This study established a multidimensional analytical framework for resolving tissue-specific chemical variation in complex medicinal plant materials and demonstrates its utility for integrating chemical profiling, spatial mapping, targeted quantification and biological evaluation.