In this study, a degree substitution of 0.796 was obtained through the process of carboxymethylation (CMG). Carboxymethyl glucans with three different molecular weights (CMG-A, CMG-B and CMG-C) were obtained using membrane separation technology. Structural characterization and in vitro antioxidant activity were also evaluated. As per the outcomes of infrared spectroscopy spectroscopy and Nuclear magnetic resonance studies, CMG-A, CMG-B, CMG-C and contained carboxyl methyl groups. The substitution order of carboxymethylation branched-chain was as follows: 6δ > 4δ > 2δ. Atomic Force Microscope images obtained from the analysis of dilute aqueous solution (0.1 mg/mL) showed that some of the structures in CMG-A, CMG-B and CMG-C, were triple-helical species coexisting with larger aggregates and single chains. In vitro antioxidant experiment shown that the CMG-C had the best antioxidant property, the half-inhibitory concentration of hydroxyl radical scavenging, iron chelation and ABTS scavenging were 0.319, 0.168 and 1.344 mg/mL, respectively.
Keywords: Carboxymethyl glucans; in vitro antioxidant activity; the structure of carboxymethyl glucans.