Effect of gallic acid on STZ induced diabetic nephropathy in experimental animals.

YA Kulkarni, MS Garud, NM Panchal. SPP School of Pharmacy & Technology Managment, SVKM\'s NMIMS, Mumbai, India

Diabetic nephropathy is one of the most serious complications of diabetes mellitus, which may lead to end-stage renal disease. A large number of drugs have been discovered from plants. Tannins are one of the important classe of phenolics compounds found in plants. Gallic acid (GA) belongs to class of hydrolysable tannins found in medicinal plants. Gallic acid has shown significant antidiabetic effects and cardio protective effects in diabetes. The aim of present study was to investigate the effects of gallic acid in streptozotocin (STZ) induced diabetic nephropathy in rats. The study protocol was approved (no- CPCSEA/IAEC/SPTM/P-21/2013) by Institutional Animal Ethics Committee which was formed in accordance with norms of Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA), India. Diabetes was induced in male Sprague-Dawley rats by injecting STZ (49 mg kg-1, i.p.). Rats with plasma glucose level >250 mg/dl after 48 h post administration of STZ were included in the study as diabetic animals. One group of rats was kept as control which received sodium citrate buffer (i.p.). After 4 weeks of STZ administration, the animals were divided into three groups - one group was kept as diabetic control and two groups received gallic acid at dose of 50 and 100 mg/kg. The gallic acid in water was administered orally for four weeks.Biochemical parameters like glucose, blood urea nitrogen (BUN) and creatinine were assessed from plasma. The oxidative stress was measured by renal malonaldehyde and the antioxidant enzymes superoxide dismutase and catalase from kidney homogenate. The kidney was subjected to histopathological analysis at the end of the treatment.

Four weeks treatment with gallic acid showed significant decrease (p<0.001) in glucose, BUN and creatinine levels (table 1).

Table 1 Effect of gallic acid (GA) on biochemical parameters.

††† p<0.001 vs normal control. ***p<0.001 vs diabetic control.(Student’ s t test).

Diabetic control rats showed higher levels of TBARS as compared to normal control rats (p<0.001). GA at selected doses significantly (p<0.05) reduced the levels of TBARS in diabetic rat kidney. Treatment with GA at dose of 100 mg/kg showed an increase in the SOD and catalase activity (p<0.05) in diabetic animals. The light microscopic findings of kidneys of control rats showed normal glomeruli and afferent arterioles. The kidneys of diabetic rats showed marked histological severe changes like tubular vacuolations, glomerular thickening. The treatment with gallic acid decreased the pathological changes in glomeruli and tubules in diabetic kidney.

In conclusion, gallic acid ameliorated the early diabetic nephropathy in rats.

(1) Kulkarni YA & Addepalli V, FASEB J 24: 569.5, 2010