Structural characterization and hypoglycaemic effects on type 2 diabetic mice of Spirulina platensis polysaccharides and Se-modified polysaccharides

Selenium-enriched polysaccharides refer to polysaccharides that contain selenium, which have emerged as a significant area of research in recent years due to the bioactivities associated with both polysaccharides and selenium. In this study, we prepared Spirulina platensis polysaccharides (SPP) and selenium-enriched SPP (SeSPP), and assessed their structural properties and hypoglycaemic functions both in vitro and in vivo . The results of the structural characterization indicated that SPP was successfully selenized. The interaction between SPP and selenium primarily occurred in the forms of Se-O-C and O-Se-O through covalent interactions. The molecular weight of SeSPP was found to be more concentrated compared to SPP, and its microscopic morphology exhibited greater complexity, including both rod-shaped and spherical particles. It was determined that SPP and SeSPP were mainly composed of glucose, rhamnose, and fucose. In vitro assays demonstrated that SeSPP exhibited significantly enhanced hypoglycaemic and antioxidant properties compared to SPP. In an in vivo model of streptozotocin- and high-fat diet-induced type 2 diabetes mice, SeSPP improved hypoglycaemic activity by reversing body weight, blood glucose levels, glucose tolerance, insulin resistance, lipid levels, hepatic oxidative stress levels, as well as liver and pancreatic morphology and function. Consequently, SeSPP may serve as a selenium supplement that could enhance hypoglycaemic effects.