Enhancing the bioavailability of quercetin via the construction of carboxymethylated curdlan/quercetin nanocomplex

Quercetin, renowned for its antioxidant and anti-inflammatory properties, holds promise for promoting human health. However, its limited solubility and stability hinders the bioactive efficacy. This study aims to enhance the bioavailability of quercetin by developing a carboxymethylated curdlan and quercetin complex (CM-Cur/QT) through an anti-solvent dialysis strategy. The CM-Cur/QT complex exhibited a spherical structure with a diameter approximately 300 nm, demonstrating improved solubility and stability. Non-covalent interaction involving the C-7 OH, C-3 OH, C-4′ OH, and C-3′OH in quercetin (QT) and the COOH group of carboxymethylated curdlan (CM-Cur) were found to contribute to the formation of CM-Cur/QT complex. During in vitro digestion, the CM-Cur/QT complex showed enhanced bio-accessibility of QT and increased antioxidant efficacy. Additionally, the CM-Cur/QT complex facilitated internalization of QT in macrophages and exerted a potential synergistic anti-inflammatory effect, which was characterized by the inhibition of intracellular reactive oxygen species (ROS) generation and a reduction in inflammatory secretion in M1 phenotype macrophage. These findings highlight the ability of the quercetin-loaded β-glucan complex (CM-Cur/QT) to enhance the original bioactivities of QT, particularly in modulating macrophage function.