Influence of Preparation Methods of Chitooligosaccharides on Their Physicochemical Properties and Their Anti-Inflammatory Effects in Mice and in RAW264.7 Macrophages.

The methods to obtain chitooligosaccharides are tightly related to the physicochemical properties of the end products. Knowledge of these physicochemical characteristics is crucial to describing the biological functions of chitooligosaccharides. Chitooligosaccharides were prepared either in a single-step enzymatic hydrolysis using chitosanase, or in a two-step chemical-enzymatic hydrolysis. The hydrolyzed products obtained in the single-step preparation were composed mainly of 42% fully deacetylated oligomers plus 54% monoacetylated oligomers, and they attenuated the inflammation in lipopolysaccharide-induced mice and in RAW264.7 macrophages. However, chitooligosaccharides from the two-step preparation were composed of 50% fully deacetylated oligomers plus 27% monoacetylated oligomers and, conversely, they promoted the inflammatory response in both in vivo and in vitro models. Similar proportions of monoacetylated and deacetylated oligomers is necessary for the mixtures of chitooligosaccharides to achieve anti-inflammatory effects, and it directly depends on the preparation method to which chitosan was submitted.