Evaluation of efficiency of french maritime pine bark (pinus maritima) extract in HİGH-fat diet and streptozotocin-induced diabetes in rats

The aim of this project is to investigate the effectiveness of French maritime pine bark extract (PBE) in type 2 diabetic rat model induced by high-fat diet (HFD) and low dose streptozotocin (STZ). Type 2 diabetes mellitus (Tip 2 DM) is a chronic metabolic disorder characterized by insulin resistance and one of the fastest-growing epidemics of our time. Cardiovascular complications, neuropathy, retinopathy, nephropathy and vascular pathologies are the major complications of DM. Increased oxidative damage due to diabetes plays an important role in complications. The main reason of morbidity and mortality of DM is the cardiovascular disorders. Renal failure following diabetic nephropathy is also one of the main causes of morbidity and mortality in DM. Current treatment approaches is inadequate in preventing the development of renal failure. On the other hand, PBE is a complex mixture of bioflavonoids, with oligometric proanthocyanidins (OPC) as the major constituents. OPC has been reported to be one of the strongest quenchers of reactive oxigene species among the various antioxidants. This herbal medication has been reported to have beneficial effects on diabetes mellitus in a few experimental and clinical studies. In this study, DM was induced with HFD (for 4 weeks) and following low-dose intraperitonial injection of STZ (35 mg/kg) in rats. The animals were randomly divided to one of the experimental groups as follow: Control group (standard diet), high-fat diet (HFD) group, HFD and STZ-induced diabetic groups. Diabetic groups were also divided subgroups: Rats were given orally either serum physiologic (SF, diabetic control) or metformin (300 mg/kg/day, positive control) or PBE (10, 50 or 100 mg/kg/day) or combination of PBE (50 mg/kg/day) and metformin (300 mg/kg/day) for 4 weeks. At the end of the study, fasting glucose, insulin, total cholestrol, HDL-cholestrol, LDL-cholestrol, triglyceride, HbA1c, urea, creatinine, C-reaktive protein (CRP), serum nitrite/nitrate and malondialdehide (MDA) levels in the serum of rats were analyzed. Endothelial functions of isolated thoracic aortas, lipid peroxidation (MDA levels) in kidneys and histopathologic evaluations of pancreas and kidneys were also evaluated. PBE improved the increased fasting blood glucose, HbA1c and HOMA-IR levels in diabetic rats significantly. Serum CRP, MDA levels and kidney MDA levels were also increased in diabetic rats, but only serum MDA levels reached statistically significance. Treatment applications led to decrease in these increased parameters. Beneficial effects of treatment on diabetic injury were also determined in histopathologic studies of pancreas and kidneys. Beneficial effects of PBE obtained from this study may contribute to using PBE, alone or in combination with other antidiabetic agents, in order to prevent the complications of diabetes mellitus.