Eugenol ameliorates insulin resistance, oxidative stress and inflammation in high fat-diet/streptozotocin-induced diabetic rat

Eugenol, a phenolic compound present in many plant essential oils, demonstrated anti-diabetic activity but the underlying mechanisms are not fully understood. The aim of the present study was to examine the anti-diabetic, anti-oxidative and the anti-inflammatory effect of eugenol in high-fat-diet (HFD) and streptozotocin (STZ)-induced diabetic rats. Additionally, the effect of eugenol on the insulin sensitivity and on skeletal muscle protein contents of glucose transporter-4 (GLUT4) and AMP-activated protein kinase (AMPK) was investigated.HFD/STZ-induced diabetic rats were treated orally with eugenol (10 mg/kg) for 45 days. After the end of the experiment, blood and skeletal muscle samples were collected. Metformin was used as positive control.The anti-diabetic effects of eugenol were demonstrated by the significant reduction in the levels of serum glucose, triglyceride, cholesterol, Low-density lipoprotein, malondialdehyde and interleukin-6 in the treated group compared to the diabetic group. Additionally, eugenol treatment significantly restored the decreased serum levels of insulin and glutathione when compared to that of the diabetic control rats. The homeostasis model assessment of insulin resistance (HOMA-IR) was significantly lower in rats treated with eugenol than in the diabetic rats. The skeletal muscle protein contents of GLUT4 and AMPK were higher in the eugenol treated group than in the diabetic control group.Eugenol possesses potent anti-oxidative and anti-inflammatory effect in HFD/STZ-induced diabetic rats. Moreover, eugenol facilitates insulin sensitivity and stimulate skeletal muscle glucose uptake via activation of the GLUT4-AMPK signaling pathway. Eugenol could represent a promising therapeutic agent to prevent type 2 diabetes.