Structural characterization and hypolipidemic activity of a natural polysaccharide from Suaeda salsa L.

Herein, the identification and analysis of a newly discovered hypolipidemic polysaccharide extracted from Suaeda salsa L., SS3-N1, is reported. The weight-average molecular weight (Mw), number-average molecular weight (Mn), and dispersity (Ð) of SS3-N1 were determined to be 45.50 kDa, 34.21 kDa, and 1.33, respectively. This polysaccharide primarily consists of galactose (50.80 %) and arabinose (30.70 %), with lower proportions of xylose, mannose, guluronic acid, rhamnose, glucuronic acid, ribose, and fucose. Methylation and NMR analyses indicated that its backbone was primarily composed of R → 3,6)-β-D-Galp-(1 → R and R → 5)-α-L-Araf-(1→ residues. The sugar units at the reducing and nonreducing ends were identified as R → 4)-β-D-Xylp-(1 → R and R → 3)-β-D-Galp-(1 → R, respectively. In addition, α-L-Araf (1 → R side branches were incorporated at the C-3 position of R → 3,6)-β-D-Galp-(1 → R. At 100 μg/mL, SS3-N1 surpassed the lipid-lowering efficacy of the positive control, atorvastatin (0.4 μM), in an egg yolk powder (EYP)-induced hyperlipidemic zebrafish model. This effect may be attributed to the modulation of cholesterol metabolism due to the upregulation of nrf2, ho-1, ampk, ppara, and cyp7a1 gene expression and the downregulation of acaca and hmgcr gene expression. Such dual gene regulation inhibits fatty acid and cholesterol synthesis, suggesting potential applications for the natural hypolipidemic polysaccharide derived from S. salsa L.