Neural activity analysis of pure chito-oligomer components separated from a mixture of chitooligosaccharides.

Chitooligosaccharides (COSs) are obtained from the in vivo and in vitro degradation of chitosan, which is a natural biomaterial used successfully for peripheral nerve repair. Also, COSs have been reported to be beneficial for the nervous system and especially able to promote peripheral nerve regeneration. To determine which component in a mixture of COSs was really responsible for the neurotrophic action of COSs, this study was performed to separate the active components of COSs and compare the neural activity of different pure components. Hydrophilic interaction liquid chromatography (HILIC) was used to separate 5 chito-oligomers with single degrees of polymerization (DPs) from a mixture of COSs. They were chitobiose, chitotriose, chitotetraose, chitopentaose, and chitohexaose with DPs of 2-6, respectively. MTT assay indicated that chitotriose induced the greatest increase in Schwann cell survival among 5 chito-oligomers. Immunocytochemistry with anti-NF-200 showed that chitotriose significantly encouraged neurite outgrowth from dorsal root ganglion (DRG) explants with the greatest effect among 5 chito-oligomers. Our results suggest that chitotriose may be a key component in COSs mixture.