Regioselective Glycosylation of Demethylbellidifolin by Glycosyltransferase AbCGT Yields Potent Anti-Renal Fibrosis Compound

Glycosylation serves as an effective strategy to enhance the solubility, bioavailability, and pharmacological activity of polyhydroxyphenols. In this study, we explored the glycosylation of natural and natural-inspired phenolic compounds using the glycosyltransferase AbCGT and evaluated the anti-renal fibrotic potential of the resulting glycosides. Among them, 1,3,5,8-tetrahydroxyxanthone 5-<i>O</i>-β-D-glucopyranoside (<b>2-1a</b>), synthesized via the regioselective 5-<i>O</i>-glycosylation of demethylbellidifolin, demonstrated significant anti-renal fibrotic activity. In contrast, its homologous glycosyltransferase, UGT73AE1, predominantly glycosylated demethylbellidifolin at the 3-OH position. Molecular docking studies revealed the structural basis for this regioselectivity difference. To enhance the production of <b>2-1a</b>, we established a UDP-glucose (UDPG) recycling system by coupling AbCGT with <i>Glycine max</i> sucrose synthase (GmSuSy) and subsequently optimized the reaction conditions. Furthermore, targeted mutagenesis of AbCGT informed by molecular docking analysis identified a F138A mutant that enhanced glycosylation yield by 2.3-fold. This work develops a novel glycosyltransferase-based catalytic system and identifies a new compound with potential anti-renal fibrotic activity.