Comparison of antioxidant and analgesic effects of gallic acid and metformin in streptozotocin-induced hyperglycemic rats

Hyperglycemia is associated with decreased activity of antioxidant enzymes and damage to peripheral nerves. The present study aimed to compare the antioxidant and analgesic effects of gallic acid (a natural compound) with metformin (a chemical drug) in hyperglycemic conditions.

Hyperglycemia was induced in male rats by the intraperitoneal injection of Streptozotocin (STZ) at a dose of 60 mg/Kg. For this research, rats were assigned to four groups. Two groups were healthy control and hyperglycemic control rats that did not receive any drugs. The other two groups were hyperglycemic rats, which respectively received metformin at a dose of 300 mg/kg/day and gallic acid at a dose of 40 mg/kg/day. At the beginning of the 8-week period for all groups, every two weeks, hot-plate and tail-flick tests were taken, and at the end of the period, the rats were anesthetized, and their blood test was performed to measure the activity of antioxidant enzymes. Data analysis was performed in SPSS software using one-way ANOVA and Tukey's post hoc test.

The administration of metformin and gallic acid in hyperglycemic rats for eight weeks increased the pain threshold and the activity of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) (P<0.05).

Gallic acid, like Metformin, can be effective in the improvement of complications caused by hyperglycemic conditions. Therefore, gallic acid may have a clinical application in the treatment of diabetic patients in the future.