Hypoglycemic potential of the extracts and active compounds from the aerial parts of Dioscorea opposita (Chinese yam)

Chinese yam (Dioscorea opposita rhizoma) is extensively cultivated as a homologous plant of medicine and food. Nevertheless, its aerial parts (ADO) are frequently overlooked due to a lack of clarity regarding their edible or medicinal properties. In this study, we found that the ADO extracts significantly brought down fasting blood glucose levels, increased body weight, and improved oral glucose tolerance and liver morphology in T2DM mice. Moreover, the ADO extracts markedly decreased TC, TG, LDL and MDA levels, and enhanced HDL and SOD levels in the serum of T2DM mice. Hence, ADO extracts exhibited both hypoglycemic and hypolipidemic effects. The underlying mechanism may be linked to the up-regulation of the PI3K/Akt signaling pathway and suppression of PTP1B expression. Further effective constituent studies resulted in the isolation and identification of 14 active compounds from the ADO extracts, including a novel dimeric phenanthrene, diosopposin A. All 14 compounds exhibited potent inhibitory activities against alpha-glucosidase or PTP1B. Among these, 11 compounds demonstrated dual inhibitory effects against both alpha-glucosidase and PTP1B. This study sheds light on the hypoglycemic properties of ADO, providing support for its potential development as a functional food or adjunct medicine.