Structural characterization, antioxidant and immunomodulatory activities of a polysaccharide from a traditional Chinese rice wine, Guangdong Hakka Huangjiu.

Hakka Huangjiu, a traditional Chinese rice wine, boasts a rich history and is known for its immunomodulatory, antibacterial, anti-aging and anti-fatigue effects. However, there is limited research on the primary active components and molecular mechanism of the bioactivity of Hakka Huangjiu. To address this gap, this study assessed the structural characteristics, antioxidant, and immunomodulatory activities of the polysaccharide-1 of Guangdong Hakka Huangjiu (HP1). Structural analysis revealed that HP1 had a low molecular weight polysaccharide of 5550 Da, primarily consisting of glucose (93.2 %), with smaller amounts of xylose, mannuronic acid and galactose. Methylation and NMR analysis suggested that the main glycosidic linkages present in HP1 are α-D-Glcp-(1→, →4)-α-D-Glcp-(1 → and →6) -α-D-Glcp-(1→. Furthermore, HP1 exhibited dose-dependent DPPH·, ABTS and OH· scavenging activity. HP1 exhibited significant protection of HepG2 cells from HO damage. Additionally, HP1 induced the release of NO, TNF-α, IL-6 and iNOS in RAW264.7 cells. HP1 treatment significantly increased mRNA expression of TNF-α, IL-6, iNOS, COX-2, IL-1β and TGF-β1. These results suggested that polysaccharides HP1 may have potential as a novel natural antioxidant and immunomodulatory product for use in nutraceuticals and functional foods.