Effects of a rhizome extract of Dioscorea batatas and its bioactive compound, allantoin in high fat diet and streptozotocin-induced diabetic mice and the regulation of liver, pancreas and skeletal muscle dysfunction.

Dysfunction of glucose metabolism is associated with the occurrence of metabolic syndromes, including type 2 diabetes mellitus (T2DM). In this study, we investigated the anti-diabetic effects of yam extract and allantoin in high-fat-diet (HFD) and streptozotocin (STZ)-induced diabetic mice and the mechanism of action on the dysfunction of the liver, pancreas, and skeletal muscle.Male C57BL/6 mice were induced into a diabetic condition by HFD for 16 weeks and a single injection of STZ (120 mg/kg) and then orally administered yam extract (500 and 1000 mg/kg) or allantoin (20 and 50 mg/kg) once daily for 4 weeks. The changes in physiological parameters, serological parameters, and morphology of tissues were investigated. The expression levels of antioxidant enzymes, biogenetic proteins, and myogenetic proteins were determined in the liver, pancreas and skeletal muscle tissues of mice.The administration of yam extract and allantoin at high doses in HFD-/STZ-induced diabetic mice compared with the control group significantly decreased the increase in body weight, caloric intake, and water intake. Yam extract and allantoin significantly decreased high glucose and leptin, total cholesterol, triglyceride, low-density lipoprotein-cholesterol, aspartate transaminase, alanine aminotransferase levels and increased insulin and albumin levels in the plasma of mice. Yam extract and allantoin inhibited the structural damage of the liver with regard to fat accumulation, the pancreas with regard to hyperplasia of Langerhans' islets, and skeletal muscle with regard to atrophy and significantly increased the expression of antioxidant enzymes and mitochondria-mediated biogenetic factors in the liver, pancreas, and muscle tissues. In addition, yam extract and allantoin significantly increased the expression of myogenetic proteins in skeletal muscle tissues.Our results indicated that yam extract and allantoin improve diabetic symptoms through the regulation of oxidation and glucose imbalance in liver, pancreas, and skeletal muscle tissues in mice. These findings suggest that yam extract and allantoin can be used as antidiabetic factors in supplementary foods and medications for T2DM patients.