Possible Metabolic Pathway of a Novel Bioactive Polysaccharide Extracted from Dendrobium aphyllum: An In Vivo Study

Our previous study characterized the structure-associated immunomodulatory effects of an edible Dendrobium aphyllum polysaccharide (DAP), and the in vitro gastrointestinal digestions highlighted DAP could be digested by the GI tract in some extent. Therefore, the present study further explored the digestive properties in vivo to infer the metabolic pathway with health mice model. Results revealed that DAP-treated group showed slightly lower blood glucose levels and significantly higher (P < 0.05) enzyme activities, namely G6Pase and GDH with an increment of about 0.4 to 0.9 and 45 to 91 U/mL, respectively. Meanwhile, DAP up-regulated the expression of glucose transporters, GLUT1 and GLUT2 in the increment rates of 56.34% to 68.28% and 76.63% to 83.03%, in colon. Furthermore, the beneficial effects of DAP on colon were confirmed by the increment of four types short chain fatty acids and the health-promoting microbiota diversity. The above results successfully identify the metabolic pathways after the oral administration of bioactive DAP. PRACTICAL APPLICATION: The metabolic pathways of Dendrobium aphyllum polysaccharide, after artificially stimulated oral administration, were characterized. The most of the unabsorbed portion of DAP were utilized by the colon microbiota, resulting in the significantly increasing production of four health-promoting SCFAs. The unabsorbed portion of DAP upregulated the diversity of various beneficial microbiota genus, and meanwhile downregulated kinds of harmful microbiota genus.