Integrating MALDI-MSI of Epimedii Folium and Spatial Metabolomics of Kidney Tissues to Uncover Tissue-Specific Metabolism

Epimedii Folium (EF) is a renowned traditional herbal medicine known for its kidney-tonifying effects. However, the spatial distribution of its components in renal tissue and the resulting metabolic regulations remain poorly understood. To facilitate quality control and efficacy evaluation of EF, MALDI-MSI integrated with UPLC-MS/MS was employed to comprehensively analyze the compositional and metabolic profiles. 97 compounds including 30 flavonoids identified, MALDI-MSI analysis revealed origin- and species-specific accumulation patterns of these bioactive compounds with samples from Longnan in Gansu Province exhibiting superior phytochemical quality. Subsequently, spatial metabolomics analysis was conducted on mouse kidney tissues to investigate the tissue-specific distribution and metabolism of EF components. It demonstrated that icariin was rapidly metabolized into bioactive derivatives in the mouse kidney. To elucidate the renal mechanism of EF in greater detail, region-of-interest (ROI) analysis was implemented, enabling precise localization of metabolic changes within microstructural regions of the kidney. Results indicated that EF modulated several key renal metabolic pathways: it enhanced antioxidant capacity and urea cycling through amino acid metabolism; reduced levels of xanthine and uric acid in purine metabolism; and increased phosphatidic acid and sphingosine in lipid metabolism, thereby improving membrane antioxidant defenses.