Structural characterization of a low-molecular-weight polysaccharide from Plumula Nelumbinis and evaluation of its antioxidant and anti-inflammatory activity

Plumula Nelumbinis polysaccharides (PNP) exhibit remarkable bioactivities, however their structure-activity relationship is still not clear. Herein, a novel low-molecular-weight polysaccharide (LPNP) was isolated and refined from Plumula Nelumbinis. The structure of LPNP was characterized using High-performance gel permeation chromatography (HPGPC), monosaccharide composition analysis, NMR spectroscopy, and methylation analysis. The results revealed that LPNP had a molecular weight of 11.6 kDa, consisting six monosaccharides. Glycosidic linkages -> 3)-beta-L-Araf-(1 ->, -> 5)-beta-L-Araf-(1 ->, T-beta-L-Araf-(1 ->, -> 3)-beta-D-Galp-(1 ->, -> 4)-alpha-D-Glcp-(1 ->, -> 4)-alpha-D-Xylf-(1 ->, T-alpha-D-Xylp-(1 ->, and T-alpha-D-Glcp-(1 -> were the main types of linkages in LPNP. LPNP could strongly protect RAW264.7 cells from H2O2-induced damage by preserving stable cell viability, reducing reactive oxygen species (ROS) and malondialdehyde (MDA) production and lactate dehydrogenase (LDH) secretion, enhancing catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activity, and increasing glutathione (GSH) content. LPNP inhibited the activation of the MAPK/NF-kappa B cell pathway, thereby decreasing the expression of NO, INF-gamma, TNF-alpha, IL-6, and IL-1 beta. LPNP could be exploited as a prospective source of natural substances in functional foods or pharmaceuticals.