Selenized modification and structural characterization of Pleurotus eryngii polysaccharides and their immunomodulatory activity

The selenized modification of purified Pleurotus eryngii polysaccharides (PPEP) were carried out in a nitric acid-sodium selenite system, and the preliminary structural characterization of PPEP and selenized PPEP (613.87 μg/g of selenium) (SPPEP) were carried out by advanced instrumentation techniques. It was found that the selenization modification did not seriously affect the structure of the PPEP. However, the SPPEP exhibited a lower molecular weight, more glycosidic bonds, reduced crystallinity, and improved thermal stability. Through in vivo animal experiments, the study found that PPEP and SPPEP were non-toxic to macrophages. Furthermore, they markedly increased the thymus and spleen indices of immunocompromised mice and improved the histomorphology of these organs. Moreover, PPEP and SPPEP enhanced the mice’s immune ability by markedly increasing the level of immune factor secretion, bone marrow hematopoietic function, and macrophage phagocytic capacity. In addition, the immune activity of SPPEP was better than PPEP’s activity.