It has been reported in our previous work that selenized Artemisia sphaerocephala polysaccharides (SeASPs) with the Se content range of 168-1703μg/g were synthesized by using Na2SeO3/HNO3/BaCl2 system. In the present work, the solution property of SeASP was studied by using size exclusion chromatography combined with multi angle laser light scattering (SEC-MALLS). A decrease in df values indicated that SeASPs with different conformational features that were highly dependent on MW. SeASPs exhibited a more rigid conformation (df value of 1.29-1.52) in low molecular weight range (MW of 1.026-1.426×10(4)g/mol) and compact spherical conformation in high molecular weight range (MW of 2.268-4.363×10(4)g/mol). It could be due to the degradation of polysaccharide chains in HNO3, which was supported in monosaccharide composition analysis. Congo red (CR) spectrophotometric method and atomic force microscopy (AFM) results also confirmed the conformational transition and the evidence on the shape of the rigid chains. In vitro anti-tumor assays, SeASP2 displayed greater anti-proliferative effects against three tumor cell lines (hepatocellular carcinoma HepG-2 cells, lung adenocarcinom A549 cells and cervical squamous carcinoma Hela cells) in a dose-dependent manner. This suggested that selenylation could significantly enhance the anti-tumor activities of polysaccharide derivatives in vitro.
In this work, selenylation of Artemisia sphaerocephala polysaccharide (SeASP) was studied by using HSeO/HNO/BaCl reaction system in microwave field. SeASP exhibited the Se content range of 111-264μg/g with high yields (72.1-94.9%). C NMR results indicated that the weak C-6 substitution was occurred. The decrease (from 7.348×10g/mol to 1.736-4.667×10g/mol) in weight average molecular mass (M) of SeASP was observed in size exclusion chromatography combined with multi angle laser light scattering (SEC-MALLS) analysis. SeASP 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 SeASP showed short chains and island-like topography. In anti-tumor activity assays, SeASP 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 200μg/mL, respectively. The relatively weak inhibition effect of SeASP 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.
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