Synthesis and antioxidant evaluation of coumarin-functionalised chitosan: A potent, non-toxic free radical scavenging...

In the present study, we designed to link the coumarin molecule to chitosan via a triazole group and synthesized chitosan-coumarin derivatives, which were further quaternized in one step in order to further improve their solubility to obtain a second series of chitosan-coumarin ammonium salt derivatives. The structures of these chitosan derivatives were verified by FT-IR and ¹H NMR. They were tested for their antioxidant activities. The experimental results showed that the derivatives had excellent free radical scavenging ability. The introduction of the coumarin moiety significantly improved the antioxidant activity, and the scavenging capacity was much higher than that of the chitosan feedstock in all three antioxidant tests. Overall, the scavenging capacity of chitosan-coumarin ammonium salt derivatives was slightly higher than that of chitosan-coumarin derivatives, with the highest scavenging rates in all three tests. Compound 8B scavenged 98.74 % (0.01 mg/mL) of superoxide anion radicals, compound 8D scavenged 95.5 % (0.3 mg/mL) of DPPH radicals and compound 8A scavenged 92.97 % (0.2 mg/mL) of hydroxyl radicals. Toxicity assays used L929 cells demonstrated that there was no significant toxicity of the derivatives. The results indicated that the chitosan derivatives described herein were safe and non-toxic and have good antioxidant activity.