Abstract
Diabetic nephropathy is one of the major complications of diabetes. Oxidative stress is implicated as an important mechanism by which diabetes causes nephropathy. The aim of the study was to examine the involvement of oxidative stress in the progression of nephropathy in STZ diabetic animals and to evaluate the potential of polyphenolic extract (PPE) in the treatment of diabetes mellitus. In this study, we examined whether prolonged oral administration of polyphenolic extract of Ichnocarpus frutescens could prevent the progress or improve the outcome of diabetic nephropathy induced by oxidative stress in STZ diabetic rats. Intraperitoneal glucose tolerance test (IPGTT) revealed a significant decrease in blood glucose levels at 180 min after glucose loading in Wistar albino rats fed with PPE. During the eight weeks of experimental period, diabetic rats exhibited wide range of symptoms, including loss of body weight, hyperglycemia, polyuria, proteinuria, renal enlargement, and total renal dysfunction. A significant increase in TBARS level was observed in diabetic kidney, which was accompanied by a significant decrease in enzymatic and non-enzymatic antioxidant levels. After eight weeks, PPE-treated groups showed a lower level of blood glucose compared with non-treated STZ diabetic rats. The increases in urinary albumin and protein after eight weeks of treatment were significantly inhibited by prolonged treatment with PPE. In addition, PPE attenuates the adverse effects on hepatic biomarkers. We found that PPE can effectively protect against aldose reductase activity and protein damage (albumin glycation), and showed that its action was mainly due to enriched polyphenolic content. Our results also showed that treatment with PPE normalized the increase in hyperalgesia (i.e., the response to thermal stimuli) associated with the induction of diabetes by STZ. PPE administration in diabetic rats clearly ameliorated diabetic complications, suggesting not only a natural antioxidant but also supportive therapy for the treatment of type II diabetes.