Sulfated modification of epimedium polysaccharide and effects of the modifiers on cellular infectivity of IBDV

Nine modification conditions were designed to sulfate epimedium polysaccharide (EPS) by chlorosulfonic acid–pyridine method according to orthogonal test, and nine sulfated EPS (sEPS), sEPS1, sEPS2, sEPS3, sEPS4, sEPS5, sEPS6, sEPS7, sEPS8 and sEPS9, were obtained and their effects on IBDV infecting chick embryo fibroblast (CEF) was compared by MTT assay. The results showed that modified sEPS had significantly enhanced CEF resisting IBDV infection in comparison of non-sulfated EPS, especially, sEPS2 and sEPS5 presented better effects, which there were certain relationships in the degree of sulfate group (DS) and carbohydrate content. The optimum modification conditions were the reaction temperature of 80 °C, the ratio of chlorosulfonic acid to pyridine of 1:8 and the reaction time of 2 h.