Abstract:

Objective: To investigate selenium modification of pumpkin polysaccharide and to evaluate the in vitro
antioxidant activity and antitumor effect against human breast cancer MDA-MB-231 cells of the modified polysaccharide.
Methods: Pumpkin polysaccharide was prepared and purified and it was modified by reaction with Na2SeO3 to obtain
selenium-containing polysaccharide. Furthermore, the structure of the modified polysaccharide was characterized through
UV, IR, atomic fluorescence spectroscopies and thermogravimetric analysis. Finally, its scavenging effect on O2-· and
·OH as well as growth inhibitory effect on breast cancer cells were tested by using pyrogallol autoxidation, salicylic
acid method and methyl thiazolyl tetrazolium colorimetric assay. Results: Se=O and Se–C bonds were observed in the
structure of the target product, thus successfully achieving the selenium modification of pumpkin polysaccharide. The
selenium-containing pumpkin polysaccharide had significantly stronger scavenging effects on O2-· and ·OH than ordinary
pumpkin polysaccharide, which were concentration-dependent. Meanwhile, the modified polysaccharide also inhibited the
growth of human breast cancer cells in a dose-dependent manner more significantly than did the unmodified one.

Key words: selenium-containing pumpkin polysaccharide, preparation, characterization, activity