Mannan oligosaccharide (MOS) is well-known as an effective fed supplement for livestock to increase their nutrients absorption and health status. Pentasaccharide of mannan (MOS5) was reported as a molecule that possesses the ability to increase tight junction of epithelial tissue, but the structure and mechanism of action remains undetermined. In this study, the mechanism of action and structure of MOS5 were investigated. T84 cells were cultured and treated with MOS5 compared with vehicle and compound C, a 5'-adenosine monophosphate-activated protein kinase (AMPK) inhibitor. The results demonstrated that the ability of MOS5 to increase tight junction integration was inhibited in the presence of dorsomorphine (compound C). Phosphorylation level of AMPK was elevated in MOS5 treated group as determined by Western blot analysis. Determination of MOS5 structure was performed using enzymatic mapping together with 1H, 13C NMR, and 2D-NMR analysis. The results demonstrated that the structure of MOS5 is a β-(1,4)-mannotetraose with α-(1,6)-galactose attached at the second mannose unit from non-reducing end.
Keywords: AMPK activation; Trans-epithelial electrical resistance; mannan oligosaccharide; tight junction integration.