Neurodegenerative disease involves an inflammatory response in the central nervous system characterized by an increase in inflammatory cytokines and activation of microglial cell. To reveal the immune regulation activity of κ-carrageenan oligosaccharides (KOS) on microglia cell activated by LPS and the relationship between the sulfate group content of KOS and its immune regulation activity, KOS was prepared by enzymatic hydrolysis. The degradation products of κ-carrageenan were analyzed by high performance liquid chromatography (HPLC), ESI-TOF-MS and (13)C NMR spectroscopy, and the results indicated that the hydrolyzed products of the κ-carrageenase were κ-neocarrabiose-sulfate, κ-neocarrahexaose-sulfate and κ-neocarraoctaose-sulfate, respectively. Then desulfated derivatives of KOS (DSK) were obtained with DMSO-methanol-pyridine method. The effect of KOS and DSK on the viability of microglia cell activated by LPS was determined with MTT method. Griess assay and ELISA method were used to determine the contents of NO/NO(2-), TNF-α and IL-10 released by activated microglia cell, respectively. The results showed that KOS could inhibit the viability and content of NO, TNF-α and IL-10 released by LPS-activated microglia cell dose dependently. Compared with that of KOS, the inhibiting activity of DSK is weaker. So it could be concluded that KOS could protect microglial cell from being activated by LPS, and there was a positive relationship between the sulfate group content of KOS and its protection function.
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