Microwave-assisted synthesis, structure and anti-tumor activity of selenized Artemisia sphaerocephala polysaccharide

In this work, selenylation of Artemisia sphaerocephala polysaccharide (SeASPMW) was studied by using H2SeO3/HNO3/BaCl2 reaction system in microwave field. SeASPMW exhibited the Se content range of 111–264 μg/g with high yields (72.1–94.9%). 13C NMR results indicated that the weak C-6 substitution was occurred. The decrease (from 7.348 × 104 g/mol to 1.736–4.667 × 104 g/mol) in weight average molecular mass (MW) of SeASPMW was observed in size exclusion chromatography combined with multi angle laser light scattering (SEC-MALLS) analysis. SeASPMW exhibited a more rigid solution conformation which might be due to the degradation of polysaccharide chains in acidic reaction reagent. This was also supported by atomic force microscopy (AFM) result that SeASPMW showed short chains and island-like topography. In anti-tumor activity assays, SeASPMW6 exhibited the inhibition rates of 32.381% and 39.776% against human non-small cell lung cancer cell line (H1650) at the concentration of 100 and 200 μg/mL, respectively. The relatively weak inhibition effect of SeASPMW was not related to cell apoptosis and cell cycle arrest, suggesting Se content might be a key factor to influence the anti-tumor activities of selenized polysaccharides in vitro.