Effects of chitosan molecular weight on its antioxidant and antimutagenic properties

Chitosan (300.0 kDa) was enzymatically degraded to obtain six degraded chitosans with molecular weights (MWs) of 156.0, 72.1, 29.2, 7.1, 3.3, and 2.2 kDa. The antioxidant and antimutagenic properties of all seven chitosan samples were evaluated in vitro. The antioxidant scavenging activities of chitosans on hydrogen peroxide and 2, 2-diphenyl-1-picryl hydrazyl radical, and on chelating ferrous ion were significantly increased with chitosan's decreasing MW, with 2.2-kDa chitosan have the highest impact. All seven chitosan samples exhibited strong anitmutagenic effects against direct (4-nitroquinoline 1-oxide) and indirect (benzo[a] pyrene) mutagens in the presence of rat liver enzyme S9 mix in Salmonella typhimurium TA 98 and TA 100. The effect of MW on antimutagenicity was similar to that on antioxidant activity. The underlying mechanism for chitosan antimutagenicity proved to be its desmutagenic effect on mutagens.