State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201 Yunnan, People's Republic of China; University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201 Yunnan, People's Republic of China; Bio-Innovation Center of DR PLANT, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201 Yunnan, People's Republic of China.
Carbohydr Polym. 2020 Aug 1;241:116326. doi: 10.1016/j.carbpol.2020.116326. Epub 2020 Apr 30.
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 Ca/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 Ca/calmodulin/CaMKII and MAPK pathways.
两种多糖，分别命名为 DOP-1 和 DOP-2，分子量分别为 6.8 kDa 和 14.3 kDa，从铁皮石斛茎中分离和纯化得到。单糖组成、傅里叶变换红外光谱、甲基化和核磁共振分析表明，DOP-1 和 DOP-2 可能具有由 →4)-β-d-Glcp-(1→、→4)-β-d-Manp-(1→、→4)-2-O-乙酰基-β-d-Manp-(1→和→4)-3-O-乙酰基-β-d-Manp-(1→组成的主链。体内试验表明，铁皮石斛多糖（DOP）对链脲佐菌素诱导的糖尿病大鼠具有显著的降血糖作用，同时血清胰岛素和胰高血糖素样肽-1（GLP-1）水平升高。进一步的体外实验表明，DOP 诱导的 GLP-1 分泌被细胞内钙螯合剂、钙/钙调蛋白依赖性蛋白激酶（CaMK）II 抑制剂、特定的钙敏感受体拮抗剂和 p38-丝裂原活化蛋白激酶（MAPK）抑制剂抑制。这些结果表明，DOP 通过刺激 GLP-1 分泌可能降低空腹血糖水平，并且细胞内 DOP 诱导的 GLP-1 分泌涉及 Ca/calmodulin/CaMKII 和 MAPK 途径。
