Recent advances in selenopolysaccharides: synthesis, structural characteristics, biological activities, and applications

Selenopolysaccharides (SePSs) are organic Se-polysaccharide conjugates synthesized by chemical or biological methods, exhibiting superior biological activities compared to individual Se or polysaccharides, such as enhanced antioxidant, immunomodulatory, and antitumor properties. This review summarizes recent progress in SePS research, including their classification into natural and synthetic types, with emphasis on synthetic strategies and their pros and cons. It elaborates on structural characteristics of SePSs, including Se binding forms, selenylation-induced changes in molecular weight and stability, and analytical techniques for characterization. Key biological activities and mechanisms are discussed: antioxidant effects via scavenging reactive oxygen species and regulating the Nrf2 pathway; immunomodulation through activating TLR2/TLR4 signaling; and antitumor activity by inducing mitochondrial apoptosis and blocking cell cycles. Other bioactivities like hypoglycemic and neuroprotective effects are also noted. Applications in medicine, food industry, and agriculture are highlighted. Current challenges and future directions are addressed, providing a reference for SePS research and exploitation. • Selenopolysaccharides show enhanced bioactivities vs. Se or polysaccharides alone. • Synthetic methods enable high Se content and industrial production. • Multiple techniques characterize their structure and properties. • Potential applications in medicine, food, and agriculture.