Physicochemical property changes of Dendrobium officinale leaf polysaccharide LDOP‐A and it promotes GLP‐1 secretion in NCI‐H716 cells by simulated saliva‐gastrointestinal digestion

A polysaccharide LDOP‐A with a molecular weight of 9.9 kDa was isolated and purified from Dendrobium officinale leaves by membrane separation, cellulose column, and dextran gel column. The Smith degradable products, methylation products, and nuclear magnetic resonance analysis showed that LDOP‐A may be composed of →4)‐Glc‐(1→, →3,6)‐Man‐(1→, and →6)‐Glc‐(1→sugar residues. In vitro, simulated digestion assays showed that LDOP‐A could be partially digested in the stomach and small intestine, and produced a large amount of acetic acid and butyric acid during colonic fermentation. Further cell experiment results illustrated that LDOP‐A‐I (LDOP‐A digested by gastrointestinal tract) could induce glucagon‐like peptide‐1 (GLP‐1) secretion in NCI‐H716 cells without showing any cytotoxicity.