Facile synthesis of carboxymethyl chitosan quaternary ammonium derivatives and the evaluation on antioxidant potential in vitro and in vivo.

New series of carboxymethyl chitosan (CMCS) and carboxymethyl chitosan quaternary ammonium (TMCMCS) derivatives with correct structures were synthesized. In vitro chemical antioxidant assays showed that all derivatives exhibited significant free-radical scavenging activity, reaching over 70% at 1.6 mg/mL. Meanwhile, TMCMCS derivatives demonstrated remarkable protective and reparative effects against H2O2-induced oxidative damage in L929 cells, including a 10-30% increase in cell viability, a greater than 30% enhancement in wound healing rate, and a reduction of over 50% in ROS levels. Furthermore, in vivo antioxidant experiments in acetaminophen-induced liver injury model confirmed that the most effective TMCMCS derivative, 2 g, enhanced the systemic antioxidant ability. This was quantitatively evidenced by the marked reduction of approximately 20% in serum transaminase activities and the levels of inflammatory factors. Molecular docking studies also revealed the mechanism underlying potent antioxidant activity. In summary, these findings highlight the significant potential of TMCMCS derivatives in developing antioxidant food additives.