OXIDATIVE DEPOLYMERIZATION OF CHITOSAN BY HYDROXYL RADICAL

Oxidative depolymerization of chitosan induced by oxygen radical-gener ating systems was studied, Chitosan, but not chitin, was susceptible t o oxidative depolymerization by hydroxyl radical generated through Cu( II)-ascorbate and ultraviolet-H2O2 systems in time- and concentration- dependent manners. Superoxide, H2O2, and singlet oxygen did not cause depolymerization. Metal ion chelators inhibited depolymerization by Cu (II)-ascorbate system, suggesting that the formation of chitosan-coppe r ion complex is important in the oxidative depolymerization. The mole cular weight of the initial product during depolymerization was simila r to that of glucosamine, The results suggest that copper ion could te nd to coordinate to the NH2-groups at the terminal of chitosan and hyd roxyl radical generated at its binding site cut off chitosan at the ne ar position.