Study on preparation of oligochitosan by gamma Co-60 irradiation of chitosan-H2O2 solution and investigation of antioxidant activity

Abstract

Study on degradation of chitosan to prepare oligochitosan by gamma Co-60 iưadiation of chitosan solution (5 %) in the presence of hydrogen peroxide (1 %) was carried out. The average molecular weight (Mw) of degraded chitosan (oligochitosan) was analyzed by gel permeation chromatography (GPC). The structure of resultant chitosan and oligochitosan was characterized by Fourier-transform infiured (FT-IR) and ultraviolet visible (UV-vis) spectra. Results showed that oligochitosan with Mw less than 10 kDa could be efficiently prepared at dose range from 10 to 20 kGy.The antioxidant activity of low Mw chitosan and oligochitosan (44.4, 17.4, 10.2 and 4 1 kDa) was investigated using free radiacal 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS'^. Results showed that low Mw oligochitosan was more effective for antioxidant activity compared with that of high Mw. In particular, the antioxidant activity was of 69,9, 84.5, 89 2 and 99.3 % for Mw of chitosan and oligochitosan of 44.4, 17.4, 10.2 and 4.1 kDa, respectively at the same reaction time of 90 min Thus, oligochitosan prepared by gamma Co-60 iưadiation can be potentially applied as natural antioxidant agent.