Microwave-assisted synthesis of chitosan biguanidine hydrochloride and its antioxidant activity in vitro

Chitosan biguanidine hydrochloride (CSGH) was synthesized by guanidinylation of chitosan hydrochloride (CSH) under microwave irradiation and characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, and element analysis. The antioxidant activity of CSGH was evaluated by both chemical and cellular methods. The results showed that CSGH was better than CSH but slightly inferior to ascorbic acid (Vc) for scavenging 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radicals, and the DPPH center dot scavenging ability of CSGH was dose-dependent. However, cell experiments indicated CSGH had a superior repairing effect on oxidatively damaged cells. The intervention of CSGH could excellently recover the cell morphology, decrease the level of malondialdehyde, and enhance the activity of superoxide dismutase and glutathione peroxidase. CSGH could be a potential antioxidant reagent, and its antioxidant activity was reflected not only in scavenging the free radicals but also in regulating the oxidation/antioxidation balance of damaged cells. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43570.