Quercetin-chitooligosaccharide ionic complex: molecular stabilization and microbiota mediated glycemic modulation

This study established an ionic cross-linked quercetin-chitooligosaccharide (QC) complex (74.7 % encapsulation efficiency) through molecular cross linking, significantly enhancing flavonoid delivery. NMR spectroscopy confirmed that hydrogen bonding between quercetin's phenolic hydroxyls and COS amine groups enhanced its physicochemical properties, thereby improving water solubility (0.04 mmol/L) and elevating the thermal decomposition onset temperature. In the diabetic model, the complex demonstrated dual bioactivity: In diabetic models, QC demonstrated dual action bioactivity. Systemically, it activated the Nrf2/HO-1 pathway, elevating SOD and GPX activities by 8.55 % and 76.29 % respectively while reducing MDA by 40.83 %. Concurrently, it remodeled gut microbiota by lowering the Firmicutes/Bacteroidetes ratio and enriching Muribaculaceae, which correlated with increased SCFA production. COS might act as an active prebiotic, potentially enabling the Bacteroides-mediated enzymatic liberation of bioactive quercetin aglycone. This reciprocal reinforcement between microbial metabolism and host antioxidant response established a novel food matrix design paradigm for glycemic regulation through rational molecular assembly.