Spatial metabolomics analysis of Bozhou Paeoniae Radix Alba during different harvest periods based on MALDI-MSI

Paeoniae Radix Alba is derived from the dried roots of Paeonia lactiflora Pall. (Ranunculaceae). Bozhou Paeoniae Radix Alba (BBS), primarily cultivated in Bozhou City of Anhui province, accounts for over 75 % of China's total Paeoniae Radix Alba yield. It traditionally harvested in summer and autumn. However, the spatial metabolomic variations across harvesting periods remain underexplored.

This study employed MALDI-MSI to analyze BBS harvested in March, June, September, and December. Differential metabolites were screened via multivariate statistical analysis, followed by KEGG pathway enrichment and activity trend analysis. Characteristic differential metabolites' spatial distributions and biosynthetic pathways were mapped. TOPSIS evaluated metabolite variations across harvesting periods.

MALDI-MSI analysis detected 1801 metabolites across 15 classes. Screening identified 608 differential metabolites primarily comprising terpenoid glycosides, phenolic acids, and tannins. K-means clustering delineated five metabolic trends. The results shown that BBS harvested in September demonstrate significantly enhanced enrichment and accelerated accumulation rates. KEGG pathway analysis revealed metabolite distribution among 68 pathways, showing highest enrichment in secondary metabolite biosynthesis. Key metabolic shifts included: September enrichment peaks for gallic acid, mudanpioside H, and sucrose; accelerated September accumulation for paeoniflorin, benzoylpaeoniflorin, and anthraquinone (maintaining high abundance through December); while 1,2,3,4,6-penta-O-galloyl-β-D-glucopyranose, quercetin, and N-acetyl-D-tryptophan showed high March-June abundance. Biosynthetic pathways were spatially resolved. Entropy-weighted Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) evaluation confirmed September as the optimal harvesting period.

MALDI-MSI effectively elucidated spatiotemporal metabolite distribution patterns in BBS. Temporal accumulation patterns were revealed across growth cycles. Spatial analysis clarified pathway-specific metabolite distributions in different tissues. This study provides scientific evidence for optimizing harvesting strategies. It enhances comprehensive utilization of medicinal resources. The findings support further development of season-specific BBS resources.