Free radical scavenging activities of differently deacetylated chitosans using an ESR spectrometer

Three kinds of partially deacetylated hetero-chitosans (90% chitosan, 90% deacetylated chitosan; 75% chitosan, 75% deacetylated chitosan; 50% chitosan, 50% deacetylated chitosan), were prepared, and their scavenging activities were investigated against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, alkyl radical, hydroxyl radical and superoxide radical using electron spin resonance spectrometer. Five mg/ml of 90, 75 and 50% chitosan scavenged 38.72, 35.52 and 13.99% of DPPH radical, respectively. The scavenging activities of heterochitosans increased from 3 to 69.39% with increasing concentration from 1.25 to 5 mg/ml of alkyl radical. In addition, 90% chitosan with relatively high degree of deacetylation showed the highest radical scavenging effects on the hydroxyl radical and superoxide radical. These results indicate that the radical scavenging activities of hetero-chitosans depend on their degree of deacetylation and concentration. (C) 2003 Elsevier Ltd. All rights reserved.