6-Shogaol ameliorates diabetic nephropathy through anti-inflammatory, hyperlipidemic, anti-oxidative activity in db/db mice

The prevalence of type 2 diabetes mellitus has been increasing worldwide and more than two thirds of the patients may develop diabetic nephropathy (DN). However, the efficiency of existing approaches on DN progression is limited. 6-Shogaol (6-SG), a major dehydrated derivative of gingerols, possesses various biological properties. The present study was designed to evaluate the possible effects of 6-SG on DN in db/db mice and to investigate the mechanisms. We revealed that 6-SG reduced the levels of fasting blood glucose, serum insulin, C-peptide, glycosylated hemoglobin A1c, and systolic blood pressure. 6-SG decreased the levels of blood urea nitrogen (BUN), serum creatinine, urinary albumin content and albumin/creatinine ratio (ACR), ameliorated the pathological injuries of kidneys, reduced the surface area of Bowman's capsule, Bowman's space, glomerular tuft, and decreased the expression of collagen IV and fibronectin in kidneys of db/db mice. The high levels of systemic and renal triglyceride and cholesterol were decreased by 6-SG. Moreover, 6-SG exhibited anti-inflammatory effects, as reflected by reduction of tumor necrosis factor alpha (TNF alpha), monocyte chemotactic protein-1 (MCP-1), and IL-6 levels in circulation and kidneys, and decrease of NF-kappa B expression. Furthermore, 6-SG also inhibited oxidative stress and restored the expression of NF-E2-related factor 2 (Nrf2) in kidneys of db/db mice. In conclusion, we have demonstrated that 6-SG exhibits anti-diabetic and renal protective effects against DN, in which effect the anti-inflammatory, hyperlipidemic, anti-oxidative activities may be involved. Overall, 6-SG could be a promising therapeutic treatment to ameliorate diabetes and the development of DN.