Pectin lyase-modified red ginseng extract improves glucose homeostasis in high fat diet-fed mice

Abstract

Red ginseng has long been used as a traditional folk medicine for various diseases including diabetes. Recently, a preparation of red ginseng extract by pectin lyase modification has been developed and named as GS-E3D. The aim of this study is to evaluate the preventive effect of GS-E3D on hyperglycemia induced by feeding a high fat diet (HFD) in mice. GS-E3D was orally administered to C57BL/6J mice at different doses (250, 500, or 1000 mg/kg/day) for 6 weeks while on a HFD. Body weight and blood glucose were monitored weekly, and oral glucose tolerance test (OGTT) was performed at 5th week of the experiment. Glycemic indications and metabolic parameters were further measured in serum. Six weeks of GS-E3D treatment to mice significantly inhibited HFD-induced body weight gain, hyperglycemia, hyperinsulinemia and hypertriglyceridemia. Notably, GS-E3D treated mice at doses of 250, 500 and 1000 mg/kg showed 41.8%, 45.0% and 55.1% reduction in insulin resistance index, respectively, compared to HFD control mice. OGTT revealed that GS-E3D markedly prevented steep rise of blood glucose and insulin levels after glucose challenge and ameliorated HFD-induced glucose and insulin intolerance. The histological analysis showed enlarged adipocytes in HFD-fed mice whereas the adipocyte hypertrophy was prevented in GS-E3D treated mice in a dose-dependent manner. Furthermore, when peripheral glucose uptake level was assessed by total and membranous glucose transporter type 4 (GLUT4) protein contents, GS-E3D restored GLUT4 protein expression to the levels of regular diet fed mice, and dose-dependently translocated them to the plasma membrane. The results collectively show that GS-E3D ameliorates obesity-related impaired glucose tolerance by improving insulin sensitivity in the epidydimal adipose tissue.