The effects of the aqueous extract of Pterocarpus santalinus heartwood and vitamin E supplementation in streptozotocin-induced diabetic rats

Abstract

Diabetic Nephropathy (DN) is a major complication of Diabetes Mellitus (MD) resulting in end-stage renal disease. Prevention or reversal of diabetic nephropathy is a major challenge in the current management of diabetes. The aim of the present study is to evaluate the hypoglycemic, antioxidant, hypolipidemic and nephroprotective effects of the aqueous extract of the Pterocarpus santalinus L (red sandalwood) alone, and in combination with vitamin E (α-tocopherol) supplementation in streptozotocin-induced diabetic rats. Twenty five healthy adult male Wistar rats were made diabetic by STZ-induction. At the end of 16 weeks of therapy, there were significant reductions in blood glucose (p<0.001), and improvements in glucose tolerance (p<0.001) as compared to untreated diabetic rats. Significant changes were also observed in lipid peroxidation (free radical activity), tissue and organ mass and cholesterol levels. The treatment caused significant lowering of blood sugar and improvement in glucose tolerance tests (p<0.001). The treatment also resulted in a significant reduction in serum lipids and body weight (p<0.001). A decrease was observed in HbA1c (p<0.01) on regular long-term control over blood glucose levels. The antioxidant effect of the red sandal wood extract was also evident, as it caused a reduction in Malondialdehyde (MDA) in the brain, liver and muscle tissues. The extract also caused a decrease in the formation of lipid peroxidase, estimated by Thiobarbituric Acid Reactive Substance (TBARS) and increased antioxidants, Superoxide Dismutase (SOD), Catalase (CAT), glutathione peroxidase and gluthathione transferase in erythrocytes with p<0.001. Serum creatinine and urine albumin showed decreased levels after treatment and returned to control values (p<0.05). The kidneys were examined histologically for diabetic nephropathy and showed regression following treatment. Sixteen weeks combination therapy also resulted in decreases in LDL-C/ HDL-C, TC (p<0.001), TG (p<0.001) and an increase in HDL-C (p<0.001) of treated diabetic rats. The use of the aqueous extract of P. santalinus caused improvements in glycemia, lipid peroxidation and brain, liver and heart tissue masses. Key words: Pterocarpus santalinus L, red sandal wood, antioxidant, diabetic nephropathy, vitamin E, Malondialdehyde, lipid peroxidation, Catalase, Thiobarbituric Acid Reactive Substance (TBARS), streptozotocin induction.