Highly efficient free radical-scavenging property of phenolic-functionalized chitosan derivatives: Chemical...

Chitosan is an abundant and renewable polysaccharide, and chemical modification can be used to enhance the biological properties of chitosan. In this study, monophenol and ortho-diphenol were introduced to chitosan through chemical modification to get chitosan derivatives owned high antioxidant activity. Their free radical-scavenging activity against three free radicals and reduction ability was tested. Based on the four antioxidant assay, the antioxidant ability of the synthesized chitosan derivatives exhibited a remarkable improvement over chitosan. The IC₅₀ of inhibition of DPPH, hydroxyl (OH), and superoxide (O²-) radical-scavenging was 41-172, 10-89, and 14-38 μg/mL, respectively. Meanwhile, ortho-diphenol was more efficient group than monophenol on the improvement of antioxidant ability of chitosan derivatives. The possible free radical-scavenging mechanism, including the number of the hydroxyl groups and the presence ortho-dihydroxy substitution for the antioxidant ability were discussed. In vitro studies demonstrated that the constructed chitosan derivatives have good biocompatibility, and good antioxidant capacity to reduce oxidative stress. Functionalization of chitosan with phenolic group allows the possible applications on the therapy of oxidative-related diseases.