Evaluation of the protective effects of quercetin and gallic acid against oxidative toxicity in rat's kidney and HEK-293 cells.

Quercetin and gallic acid are phytochemicals with interesting pharmacological properties. We herein investigated the protective effect of quercetin (QUE) in comparison with gallic acid (GAL) against exogenously-induced oxidative damage in rats' kidney and human embryonic kidney (HEK-293) cell lines. Adult Wistar rats were treated with QUE and GAL (50 mg/kg) separately or in combination with di-n-butylphthalate (DnBP) for 14 days; and HEK-293 cells were treated with different concentrations of GAL (25-294 μM) or QUE (2-17 μM or 28-165.43 μM) singly or in combination with HO (200 μM). After treatment, the kidney and cell extracts were processed for biochemical analysis and histopathology. We found that GAL but not QUE prevented DnBP-induced increase in lipid peroxidation (2.603 ± 0.25 . 3.65 ± 0.21 μmol/mL). Treatment with QUE but not GAL was associated with increased plasma creatinine (729.09 ± 55.68 . 344.25 ± 50.78 μmol/l) and tissue malondialdehyde (3.72 ± 0.62 . 1.67 ± 0.47 μmol/mL) concentrations, along with histo-pathological changes such as glomerular and tubular degenerations. However, QUE exhibited wider therapeutic concentration ranges than GAL at which it inhibits lipid peroxidation in HEK-293 cells, and was found to inhibit HO-induced lipid peroxidation even at the lowest concentration (2 μM) that was tested (0.607 ± 0.074 . 0.927 ± 0.106 μmol/l). These suggest that the dosages required for the antioxidant protective effects of QUE in renal tissues are low.