Synthesis and antioxidant action of chitosan derivatives with amino-containing groups via azide-alkyne click reaction and N-methylation.

Amino functionality has been paid growing attention in chemical modification of polysaccharides due to their potential biomedical applications. Here, the preparation of novel antioxidant materials based on chitosan derivatives bearing amino-containing groups equipped with 1,2,3-triazole and 1,2,3-triazolium by Cuprous-catalyzed azide-alkyne cycloaddition and N-methylation was described for the first time. The structural characteristics of the synthesized derivatives were examined by FTIR, 1H NMR, and elemental analysis. The antioxidant activities of the chitosan derivatives were assessed in vitro. The results indicated that chitosan derivatives bearing 1,2,3-triazoles displayed superior antioxidant activity over pristine chitosan, especially against superoxide anion radical. Moreover, antioxidant efficiency of chitosan derivatives further enhanced after N-methylation of 1,2,3-triazole moieties with iodomethane, which is comparative to that of ascorbic acid. Notably, of all chitosan derivatives bearing 1,2,3-triazole or 1,2,3-triazolium moieties, acylhydrazine-functionalized and amino-functionalized chitosan showed the stronger antioxidant capacity than hydroxyl-modified chitosan at the test concentration. Besides, the cytotoxicities of them were also evaluated in vitro on HaCaT cells. These results suggested that amino and acylhydrazine-functionalized chitosan derivatives with 1,2,3-triazolium could be used as novel antioxidant biomaterials.