Polyphenols of Hibiscus sabdariffa improved diabetic nephropathy via regulating the pathogenic markers and kidney functions of type 2 diabetic rats

We recently demonstrated the chemical composition of Hibiscus sabdariffa polyphenol extracts (HPE), and its anti-insulin resistance property using a type 2 diabetic rat model. In the present study, we examined whether HPE prevents diabetic nephropathy, and its putative regulations of the pathogenic markers. HPE significantly inhibited albuminuria and the elevation of clearance of creatinine (CCr) caused by early diabetic nephropathy. Histological findings revealed that HPE inhibited fat deposition and advanced glycation end-products (AGE) expression in kidneys of type 2 diabetic rats. The increase of tubular connective tissue growth factors (CTGFs) and glomerular cluster of differentiation 31 (CD31) were also ameliorated by HPE. HPE reversed collagen accumulation, decreased angiotensin II type 1 receptor (AT-1) elevation, and improved oxidative stress. In conclusion, using the type 2 diabetic model, we have successfully shown that HPE not only has a benefit in reducing hyperglycaemia and hyperinsulinaemia, but can also prevent diabetic nephropathy. HPE has the potential to act as an adjuvant for diabetic therapy, and deserves further investigation. (C) 2013 Elsevier Ltd. All rights reserved.