Protective Effect of Benzoquinone Isolated from the Roots of Averrhoa carambola L. on Streptozotocin-Induced Diabetic Mice by Inhibiting the TLR4/NF-κB Signaling Pathway.

Background: Studies have demonstrated that the roots of Averrhoa carambola L. (Oxalidaceae), a traditional Chinese medicine, can be used to treat diabetes and diabetes-related diseases. Nevertheless, the potential beneficial effects and mechanism of benzoquinone isolated from the roots of Averrhoa carambola L. (BACR) on diabetes remain unclear. Methods: Diabetic Kunming mice were injected with STZ (120 mgkg(-1)) in the tail vein. Fasting blood glucose (FBG) and the change of body weight were measured after oral administration of BACR (120, 60, 30 mg/kg/d) every week. The levels of the total cholesterol (TC), triglyceride (TG), free fatty acids (FFA), glucosylated hemoglobin (GHb), fasting insulin (FINS), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were measured. The histological examination of pancreatic tissues and the TLR4/NF-kappa B pathway was analyzed by RT-PCR, immunohistochemistry and Western blot. Results: The study found that clearly the BACR obviously reduced the blood glucose, serum lipids, GHb and FINS. In addition, BACR treatment markedly reduced the release of inflammatory factors, including IL-6 and TNF-alpha, and down-regulated the expression of the TLR4/NF-kappa B pathway. Conclusion: BACR has potential benefits for the treatment of diabetes by ameliorating metabolic functions and attenuating the inflammatory response via inhibition of the activation of theTLR4/NF-kappa B pathway.