Preparation, characterization and antioxidant activity of two partially N-acetylated chitotrioses.

The preparation of chitooligosaccharides with single degree of polymerization and well-defined degree of acetylation is of significance to identify the components possessing strong biofunction. This study focuses on the preparation of two partially acetylated chitotrioses (N-acetylchitotriose and N,N'-diacetylchitotriose), involving a two-step process: (i) partially N-acetylation of chitotriose and (ii) separation of different acetylated chitotrioses. The chitotriose was N-acetylated and characterized with FT-IR and ESI-MS. N-acetylchitotriose and N,N'-diacetylchitotriose were separated from the acetylated chitotriose mixture by CM Sepharose Fast Flow. Subsequently, the antioxidant activities of two partially acetylated chitotrioses and original chitotriose were investigated, including hydroxyl radical and superoxide radical scavenging activity. The results showed that the activities of the three oligomers were in a dose-dependence manner and related to their degree of acetylation. The N,N'-diacetylchitotriose with high degree of acetylation exhibited the highest antioxidant activity.