Remodeling of Bamboo (Phyllostachys edulis) Shoot Polysaccharides by Monascus purpureus Fermentation Enhances Antioxidant Protection in Caco-2 Cells

Bamboo shoot polysaccharides possess promising bioactivities, but their high molecular weight and complex branched structures limit their functional efficacy. In this study, bamboo (Phyllostachys edulis) shoots were fermented with Monascus purpureus ATCC16426 to obtain a novel neutral polysaccharide (FBSP-1). Monosaccharide composition analysis indicated that FBSP-1 comprised glucose (Glc), xylose (Xyl), arabinose (Ara), galactose (Gal), and mannose (Man). Glycosidic linkage and nuclear magnetic resonance (NMR) spectroscopy data revealed that the backbone of FBSP-1 mainly consisted of →2)-α-Manp-(1→, →4)-α-Glcp-(1→, →3)-β-Xylp-(1→, →3)-α-Araf-(1→ and →2)-α-Araf-(1→. Compared with unfermented polysaccharide BSP-1, fermentation markedly altered the monosaccharide profile, increasing Glc, Xyl and Man, decreasing Ara and Gal, and reducing the molecular weight. In H2O2-treated Caco-2 cells, FBSP-1 significantly alleviated oxidative damage by reducing intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) levels, while enhancing the activities of superoxide dismutase (SOD) and glutathione reductase (GR), demonstrating pronounced antioxidant protective effects. Overall, this study demonstrates that Monascus fermentation is an effective strategy for the structural remodeling of bamboo shoot polysaccharides, enabling the enhancement of their antioxidant functionality and supporting their potential application as functional ingredients in plant-based antioxidant foods.