Spatial metabolomics reveals seed coat-specific accumulation of bioactive polyphenols in Setaria italica: Mechanistic insights from molecular docking and antioxidant profiling

<i>Setaria italica</i> seed coat represents an underutilized source of bioactive polyphenols. This study employed an integrated approach combining spatial metabolomics, computational screening, and in vitro assays to characterize its polyphenol composition and antioxidant properties. UPLC-MS/MS analysis revealed distinct metabolite profiles with numerous polyphenols significantly enriched in seed coats relative to kernels. Molecular docking identified Homoplantaginin as a high-affinity ligand for catalase, with molecular dynamics simulations confirming complex stability. In vitro antioxidant assays demonstrated concentration-dependent scavenging activity of Homoplantaginin against ABTS•⁺, O₂•^-, and •OH radicals. These findings highlight the potential of <i>Setaria italica</i> seed coat as a sustainable source of natural antioxidants for functional food applications, providing scientific basis for the valorization of this agricultural byproduct.