Impact of carboxymethyl cellulose on mucin-tea polyphenol interactions: insights into...

Polysaccharides and polyphenols frequently coexist in food systems and are consumed simultaneously, yet how these interactions influence polyphenol behavior in the gastrointestinal tract remains insufficiently understood. In this study, the effects of carboxymethyl cellulose (CMC) with different concentrations, molecular weights and degrees of substitution on mucin-tea polyphenol (TP) interactions were systematically investigated. Turbidity and zeta-potential measurements indicated that the addition of CMC reduced aggregation of mucin-TP complexes and increased the negative surface charge. Fluorescence spectroscopy further showed that CMC weakened TP-induced quenching of mucin intrinsic fluorescence, suggesting competitive interactions or conformational interference. Thermodynamic analysis suggested that TP-mucin binding was likely driven primarily by hydrogen bonding and van der Waals forces. Although CMC did not alter the apparent interaction mode, it significantly decreased the binding affinity, particularly under acidic conditions simulating the gastric environment. Moreover, the inhibitory effect became stronger with increasing molecular weight and decreasing degree of substitution of CMC. Molecular docking supported these results, revealing that CMC may compete for mucin binding sites or directly interact with TP molecules. These findings provide molecular-level insights into how food polysaccharides modulate mucin-polyphenol interactions and contribute to a better understanding of the factors affecting interaction behaviors of polyphenols and their gastrointestinal bioavailability. This study may offer useful implications for designing polysaccharide-based delivery or modulation systems for dietary polyphenols in food and health-related applications.