Synthesis of Se-polysaccharide mediated by selenium oxychloride: Structure features and antiproliferative activity

Selenium oxychloride (SOC) was employed as a highly reactive selenide reagent to synthesize selenized Artemisia sphaerocephala polysaccharides (SeASP). Se content of SeASP was significantly increased (similar to 22,400 mu g/g) as compared to HNO3/H2SeO3 selenylation method (1703 mu g/g). Furthermore, selenized ASP was prepared by using microwave-assisted synthesis which obviously enhanced selenylation kinetics. FT-IR, Raman, XPS and NMR results exhibited seleno-group was substituted at C6 position in the form of selenite (Se4+). SEC-MALLS suggested SOC system could effectively avoid the degradation of polysaccharide chain. Meanwhile, MALLS calculation, MB spectrophotometric method and AFM observation showed SeASP appeared spherical and rod-shaped conformation after selenylation. Seleno-groups were more likely to affect the conformational transformation of polysaccharide chains. Moreover, SeASP could significantly enhance antiproliferative activity against three tumor cells, of which the IC50 value of HepG2 was calculated as 24.35 mu g/mL. It was found that higher Se content could effectively improve the antitumor activities of Se-polysaccharides in vitro.