Korean J Nutr.  2010 Aug;43(4):333-341. 10.4163/kjn.2010.43.4.333.

Effect of Fermented Yacon (Smallanthus Sonchifolius) Leaves Tea on Blood Glucose Levels and Glucose Metabolism in High-Fat Diet and Streptozotocin-Induced Type 2 Diabetic Mice

Affiliations
  • 1Department of Nutrition Education, Graduate School of Education, Sunchon National University, Suncheon 540-742, Korea.
  • 2Department of Food and Nutrition, Sunchon National University, Suncheon 540-742, Korea. leemk@sunchon.ac.kr
  • 3Department of Development in Resource Plants, Sunchon National University, Suncheon 540-742, Korea.
  • 4Faculty of Hotel Cuisine, Daegu Polytechnic College, Daegu 706-022, Korea.

Abstract

The aim of this study was to investigate the hypolgycemic activity of water extract of fermented yacon (Smallanthus sonchifolius) leaves tea (Yacon LWE) in high-fat diet (HFD)/streptozotocin (STZ)-induced diabetic mice. Male ICR mice were fed with a HFD (37% calories from fat) for 4 weeks prior to intraperitoneal injection with STZ (100 mg/kg body weight). Diabetic mice were supplemented with two doses of Yacon LWE (0.16% and 0.8%, wt/wt) for 6 weeks. The supplementation of high-dose Yacon LWE significantly lowered blood glucose levels and plasma ALT and AST activities compared with the control group. High-dose Yacon LWE also improved the insulin tolerance without any changes in plasma and pancreatic insulin concentrations in HFD/STZ-induced diabetic mice. Yacon LWE supplementation increased the insulin staining of pancreatic beta-cells in a dose-dependent manner. Both 0.16% and 0.8% of Yacon LWE significantly elevated plasma leptin concentration, hepatic glucokinase activity and glucokinase/glucose-6-phosphatase ratio compared with the control group. However, glycosylated hemoglobin concentration was not different among the groups. These results suggest that high-dose Yacon LWE lowers the blood glucose level partly by enhancing insulin sensitivity and hepatic glucose metabolism in type 2 diabetic mice.

Keyword

fermentated yacon leaves tea; type 2 diabetes; glucose metabolism

MeSH Terms

Animals
Blood Glucose
Diet, High-Fat
Glucokinase
Glucose
Hemoglobin A, Glycosylated
Humans
Injections, Intraperitoneal
Insulin
Insulin Resistance
Leptin
Male
Mice
Mice, Inbred ICR
Plasma
Tea
Water
Blood Glucose
Glucokinase
Glucose
Hemoglobin A, Glycosylated
Insulin
Leptin
Tea
Water

Figure

  • Fig. 1 Effect of fermented yacon tea water extract supplementation on fasting blood glucose level (A) and glycosylated hemoglobin concentration (B) in HFD/STZ-induced diabetic mice. Mean ± S.E. (n = 9). Means not sharing a common letter are significantly different among groups by Duncan's multiple range test (p < 0.05).

  • Fig. 2 Effect of fermented yacon tea water extract supplementation on glucose tolerance test (A) and insulin tolerance test (B) in HFD/STZ-induced diabetic mice. Mean ± S.E. (n = 9). Means not sharing a common letter are significantly different among groups by Duncan's multiple range test (p < 0.05).

  • Fig. 3 Effect of fermented yacon tea water extract supplementation on immunohistochemical finding of islet for insulin in HFD/STZ-induced diabetic mice (× 200).

  • Fig. 4 Effect of fermented yacon tea water extract supplementation on plasma aminotransferase activity in HFD/STZ-induced diabetic mice. Mean ± S.E. (n = 9). Means not sharing a common letter are significantly different among groups by Duncan's multiple range test (p < 0.05).


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