Effects of selenylation modification on structural and antioxidant properties of pectic polysaccharides extracted from Ulmus pumila L.

The present study was carried out to determine the effects of selenylation on structural and antioxidant activities of pectic polysaccharides extracted from Ulmus pumila L. (PPU). Selenylation of PPU (Se-PPU) was synthesized by different concentrations of sodium selenites (0.2, 0.4, 0.6, 0.8, and 1.0g). Structural properties of Se-PPUs were characterized using ICP-OES, HPGPC, FE-SEM, XRD, FT-IR and NMR. After selenylation, the selenium contents and the molecular weights of PPU increased. In FT-IR analysis, a new intensive absorption band at around 667cm-1 was observed in Se-PPU. From 13C NMR spectra, the new peak at 62.41ppm was found in Se-PPU probably due to the substitution of selenyl groups. In vitro antioxidant activities of all samples were evaluated by reducing power, nitrite scavenging, superoxide dismutase like scavenging activities, hydroxyl radical scavenging activities, and DPPH radical scavenging activities. The antioxidant activities of Se-PPUs were significantly higher than those of PPU. In conclusion, Se-PPU exhibited the potential possibility of the use as an antioxidant in foods and pharmaceuticals. Furthermore, the expanded use of Se-PPU produced from Ulmus sources may be taken in account for better health improvement.