Antioxidant properties of some different molecular weight chitosans

Hisao Tomida*, Takeshi Fujii, Nobuko Furutani, Akihiro Michihara, Taira Yasufuku, Kenji Akasaki, Toru Maruyama, Masaki Otagiri, Janusz M. Gebicki, Makoto Anraku

*Corresponding author for this work

Research output: Contribution to journalArticle

101 Citations (Scopus)

Abstract

Chitosan, a cationic polysaccharide, is widely employed as dietary supplement and in pharmacological and biomedical applications. Although numerous studies have focused on its applications as pharmaceutical excipients or bioactive reagents, relationships between molecular weight (Mr) and biological properties remain unclear. The focus of this study was on the antioxidant properties of several Mr chitosans. We measured the ability of seven Mr chitosans (CT1; 2.8 kDa, CT2; 17.0 kDa, CT3; 33.5 kDa, CT4; 62.6 kDa, CT5; 87.7 kDa, CT6; 604 kDa, CT7; 931 kDa) to protect plasma protein from oxidation by peroxyl radicals derived from 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH). A comparison of the antioxidant action of high Mr chitosans (CT6-CT7) with that of low Mr chitosans (CT1-CT5) showed that low Mr chitosans (CT1-CT5) were more effective in preventing the formation of carbonyl groups in plasma protein exposed to peroxyl radicals. AAPH substantially increases plasma protein carbonyl content via the oxidation of human serum albumin (HSA). We also measured the ability of these chitosans to protect HSA against oxidation by AAPH. Low Mr chitosans (CT1-CT5) were found to effectively prevent the formation of carbonyl groups in HSA, when exposed to peroxyl radicals. Low Mr chitosans were also good scavengers of N-centered radicals, but high Mr chitosans were much less effective. We also found a strong correlation between antioxidant activity and the Mr of chitosans in vitro. These activities were also determined by using the 'TPAC' test. These results suggest that low Mr chitosans (CT1-CT3) may be absorbed well from the gastrointestinal tract and inhibit neutrophil activation and oxidation of serum albumin that is frequently observed in patients plasma undergoing hemodialysis, resulting in a reduction in oxidative stress associated with uremia.

Original languageEnglish
Pages (from-to)1690-1696
Number of pages7
JournalCarbohydrate Research
Volume344
Issue number13
DOIs
Publication statusPublished - 8 Sep 2009

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