The Selenylation Modification of Epimedium Polysaccharide and Isatis Root Polysaccharide and the Immune-enhancing Activity Comparison of Their Modifiers

Epimedium polysaccharide (EPS) and isatis root polysaccharide (IRPS) were extracted, purified, and selenizingly modified by nitric acid-sodium selenite method to obtain nine selenizing EPSs (sEPSs), sEPS1–sEPS9 and nine selenizing IRPSs (sIRPSs), sIRPS1–sIRPS9, respectively. Their effects on chicken peripheral lymphocyte proliferation in vitro were compared by MTT assay. The results showed that selenium polysaccharides at appropriate concentration could promote lymphocyte proliferation more significantly than unmodified polysaccharides, sEPS5 and sIRPS5 with stronger actions were picked out and injected into the chickens vaccinated with Newcastle disease vaccine in vivo tests. The peripheral lymphocyte proliferation and serum antibody titer were determined. The results showed that sEPS5 and sIRPS5 could elevate serum antibody titer and promote lymphocyte proliferation more significantly than unmodified polysaccharides, sEPS5 possessed the strongest efficacy. These results indicate that selenylation modification can significantly enhance the immune-enhancing activity of EPS and IRPS, and sEPS5 can be as a new-type immunopotentiator of chickens.