Water-soluble polysaccharides from Torreya grandis nuts: Structural characterization and anti-inflammatory activity

Torreya grandis (T. grandis) nuts are widely consumed as a functional food in China. In this study, we investigated the structural characteristics of T. grandis nuts polysaccharides and evaluated their potential biological functions with anti-inflammatory activities. Polysaccharides (TGP) were extracted from T. grandis nuts using water extraction and alcohol precipitation methods. Through a series of purification steps, three heteropolysaccharides (TGP-0a, TGP-2a, and TGP-3a) with distinct molecular weights, monosaccharide compositions, and surface morphologies were isolated. Their anti-inflammatory activities were screened, and TGP-0a was shown to be the most effective component. By combining NMR and methylation studies, TGP-0a was predominantly composed of linear α-1,4-glucan region and linear β-1,4-(gluco)mannan region. In cellular anti-inflammatory assays, TGP-0a significantly diminished the release of pro-inflammatory cytokines. Furthermore, by lowering the levels of iNOS and COX-2, TGP-0a decreased the release of inflammatory mediators (NO and ROS), thereby lowering oxidative stress and inflammatory response. In conclusion, T. grandis nut polysaccharides, particularly TGP-0a, show strong potential as natural anti-inflammatory agents for functional foods and pharmaceutical applications.