Structural characterization and hypoglycemic effect via stimulating glucagon-like peptide-1 secretion of two polysaccharides from Dendrobium officinale

• Published in: Carbohydrate polymers 2020-08, Vol.241, p.116326-116326, Article 116326
• Main Authors: Kuang, Meng-Ting, Li, Jin-Yu, Yang, Xiao-Bei, Yang, Liu, Xu, Jing-Yue, Yan, Sha, Lv, Yong-Feng, Ren, Fu-Cai, Hu, Jiang-Miao, Zhou, Jun
• Format: Article
• Language: English
• Subjects: Animals; Cell Line; Dendrobium - chemistry; Dendrobium officinale; Diabetes Mellitus, Experimental - drug therapy; GLP-1enteroendocrine STC-1 cells; Glucagon-Like Peptide 1 - blood; Glucagon-Like Peptide 1 - metabolism; Hypoglycemic Agents - chemistry; Hypoglycemic Agents - pharmacology; Insulin Secretion; Male; Mice; Plant Extracts - chemistry; Plant Extracts - pharmacology; Polysaccharides - chemistry; Polysaccharides - pharmacology; Rats; Rats, Sprague-Dawley; Signaling pathway; Structural characterization; STZ-induced diabetic rats
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2020.116326

•Structural characterization of two polysaccharides from Dendrobium officinale were described.•DOP performed the hypoglycemic activity via stimulating GLP-1 secretion in STZ-induced diabetic rats and STC-1 cells.•Ca2+/CaM/CaMKII and MAPK pathways might involve in the intracellular DOP-induced GLP-1 secretion.•The repeated unit of backbone of DOP-1 and DOP-2 might be the effective unit of DOP-induced GLP-1 secretion. Two polysaccharides, named DOP-1 and DOP-2, with molecular weights of 6.8 kDa and 14.3 kDa, respectively, were isolated and purified from the stems of Dendrobium officinale. Monosaccharide composition, Fourier-transform infrared spectroscopy, methylation, and nuclear magnetic resonance analyses indicated that DOP-1 and DOP-2 may have a backbone consisted of →4)-β-d-Glcp-(1→, →4)-β-d-Manp-(1→, →4)-2-O-acetyl-β-d-Manp-(1→ and →4)-3-O-acetyl-β-d-Manp-(1→. In vivo assays showed that D. officinale polysaccharides (DOPs) exerted significant hypoglycemic effects accompanying increased serum insulin and glucagon-like peptide-1 (GLP-1) levels in streptozotocin-induced diabetic rats. Further in vitro experiments showed that DOP-induced GLP-1 secretion was inhibited by an intracellular calcium chelator, a Ca2+/calmodulin-dependent protein kinase (CaMK) II inhibitor, a specific calcium-sensing receptor antagonist, and a p38-mitogen-activated protein kinases (MAPK) inhibitor. These results indicated that DOPs may decrease fasting blood sugar levels by stimulating GLP-1 secretion and that intracellular DOP-induced GLP-1 secretion involved the Ca2+/calmodulin/CaMKII and MAPK pathways.