Large-Scale Semisynthesis of Bioactive Procyanidin B2 3,3′-di- <i>O</i> -gallate: Structural Characterization, Simulated <i>In Vitro</i> Digestion, and Protective Effects against Colitis

Galloylated procyanidins (GPCs) possess superior biological activities to nongalloylated ones but are scarce in nature. In this study, a novel semisynthetic approach combined with high-speed countercurrent chromatography (HSCCC) was developed for the large-scale preparation of procyanidin B2-3,3'-di-<i>O</i>-gallate (B2G2). Antioxidant evaluations via DPPH, ABTS, and FRAP assays demonstrated that B2G2 surpassed its structural units (procyanidin B2-3'-<i>O</i>-gallate, procyanidin B2, epicatechin gallate, and epicatechin), a result linked to its elevated galloylation level and polymerization degree. <i>In vitro</i> digestion experiments indicated that B2G2 exhibited greater stability than its structural units under simulated gastrointestinal conditions, providing a basis for subsequent <i>in vivo</i> evaluation. A preliminary <i>in vivo</i> safety evaluation demonstrated that B2G2 exerted no adverse effects. In dextran sodium sulfate (DSS)-induced colitis mice, B2G2 administration was associated with attenuation of tissue injury, reduced inflammatory cytokine levels, and decreased levels of oxidative stress markers. Our findings highlight B2G2 as a promising novel functional food ingredient with gut-protective properties.