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The digestibility and prebiotic potential of galactomannan oligosaccharides prepared from Cassia seed gum (CMOS) was studied. CMOS were tolerant against simulated gastrointestinal digestion. During in vitro human fecal fermentation with CMOS, the microbiota composition was significantly changed with promoted growth of potential beneficial genera (i.e. Bifidobacterium, Lactobacillus, Bacteroides, Veillonella) while that of potential harmful genera (i.e. Fusobacterium, Lachnospiraceae, and Sutterella) was inhibited. Short chain fatty acids were produced with decreased medium pH, while acetic acid (20.85 mM) and propionic acid (19.77 mM) were the predominant metabolites. For CMOS utilization, α-galactosidase and β-mannosidase were involved with the enzyme activity reached the maximum after 3 h fermentation. The HPAEC chromatograms showed that CMOS with DP = 3 and 4 were prior utilized through enzymatic hydrolysis within 36 h fermentation. Findings gained here will introduce the utilization and targeted production of CMOS (DP = 3 and 4) as prebiotics with defined structural features.

The effects of Konjac mannan oligosaccharides (KMOS) on diphenoxylate-induced constipation in mice were investigated in the present study. After administration with KMOS at 1800 mg/kg·bw, the weight and number of black feces within 24 h, and the gastrointestinal transit ratio were distinctly increased by 96.8%, 156.5% and 45.3%, respectively. Furthermore, KMOS regulated the levels of enteric nervous system parameters, including motilin, somatostatin, substance P, acetyl cholinesterase, endothelin and vasoactive intestinal peptide. Additionally, KMOS could recover the characteristics of small intestine villi and inhibit the reduction of mucosal thickness. KMOS administration produced more short chain fatty acids and lactic acid compared with the control group. The availability of 5-hydroxytryptamine and the expression of serotonin transporter were ameliorated in the KMOS treatment groups. Collectively, these findings suggested that KMOS could be considered as a functional food material for regulating intestinal function and alleviating constipation.