Synthesis and antioxidant activity of phosphorylated polysaccharide from Portulaca oleracea L. with H3PW12O40 immobilized on polyamine functionalized polystyrene bead as catalyst

Esterification of polysaccharide had been carried out by catalysis using a series of catalysts, which were synthesized by H3PW12O40 (HPW) immobilized on chloromethylated polystyrene bead (PSC) and named as PS-EDA-HPW, PS-DETA-HPW, PS-TETA-HPW and PS-(AST-HPW)n according to different linker in the reaction system. The catalysts were characterized by FTIR spectroscopy, nitrogen adsorption, X-ray diffraction and inductively coupled plasma atomic emission spectrophotometer. PS-(AST-HPW)n showed the highest efficacy on esterification of polysaccharide. Four phosphorylated derivatives (POP1-p) of a native polysaccharide (POP1) from Portulaca oleracea L. with different degree of substitution (DSp) were obtained using PS-(AST-HPW)n as the catalyst. Chemical equilibrium was established as quickly as 10 h with the content of P more than 5%. Compared with native POP1, POP1-p exhibited superior antioxidant activities in vitro, which indicated that phosphorylated modification could enhance antioxidant activities of POP1. It was obvious that the DSp had a significant effect on the antioxidant activity.

Catalysts were synthesized for polysaccharide esterification by H3PW12O40 (HPW) immobilized on chloromethylated polystyrene bead (PSC), and were characterized by FTIR spectroscopy, nitrogen adsorption, X-ray diffraction and inductively coupled plasma atomic emission spectrophotometer.Figure optionsDownload high-quality image (155 K)Download as PowerPoint slideHighlights
► Esterification of biomacromolecules was carried out by solid catalysis.
► Antioxidant activities of polysaccharide were increased by molecular modification.
► Catalysis was synthesized by H3PW12O40 immobilized on polystyrene bead.