Hypoglycemic effect of Smallanthus sonchifolius (yacon) extracts on animals with streptozotocin-induced diabetes

This study was performed to investigate improvements in diabetes mellitus by extracts of yacon in streptozotocin (STZ)-induced diabetic rats. Fifty rats were divided into a normal group and four experimental groups. STZ (45 mg/kg) was injected intraperitoneally to induce type I diabetes in the four experimental groups. Yacon extracts were administered for 5 weeks. Forty-five ICR mice were also divided into one positive control group and four experimental groups for the oral glucose tolerance test (OGTT) after fed yacon extract. The control group did not eat any yacon extracts, while Group 1 (GI) was fed 125 mg/kg of yacon extracts, Group 2 (GII) was fed 250 mg/kg of yacon extracts, and Group 3 (GIII) was fed 500 mg/kg of yacon extracts. After treatment for 5 weeks, blood glucose in GIII group showed decreased tendency at the 5 week. In OGTT by glucose, the glucose level of yacon treatment group in diabetic rats was significantly decreased compared to the glucose level of the control group, but there was no difference in OGTT by maltose. In ICR mice, the glucose level of the experimental group in OGTT by maltose was significantly decreased compared to the control group. The area of the islets of Langerhans was increased by yacon treatment in a dose-dependent manner on diabetic rats. Insulin concentration of the GIII group was also decreased compared to the control group, while the concentration of fructosamine, total cholesterol, and triglycerides in serum showed no difference. OGTT by glucose or maltose in ICR mice or diabetic rats, area of the Islets of Langerhans, and insulin concentration improved. Yacon treatment may be a useful therapeutic and preventive strategy for diabetes mellitus.