Preparation, composition analysis, and immunomodulatory activity of water-soluble glycopeptides from Hemicentrotus pulcherrimus gonads.

Glycopeptides have attracted increasing attention due to their favorable solubility, stability, and bioactivity. Herein, three low molecular weight (< 4.0 kDa) and water soluble glycopeptide fractions were obtained from sea urchin gonads. The content of amino sugar residues remarkably increased from HPGP-1 to HPGP-3 in the glycan fraction that forms O-glycosidic bonds with the peptide fragment. Their macrophage activation exhibited stability under gastrointestinal conditions. In particular, HPGP-3 enriched with glucosamine, galactosamine, and tyrosine showed the best immunoregulatory potency in vitro and in vivo at 7.8 μg/mL and 15 mg/kg, respectively. The glycopeptides showed protective effects on immune function in CTX-induced immunosuppressed mice. Moreover, HPGP-3 reshaped the gut microbiota composition and increased the relative abundance of beneficial genera, such as Akkermansia and Bacteroides. This work provides new cases of glycopeptides and reveals their potential application as prebiotics and immunomodulators.