Repeated 28-day oral dose toxicity of onion skin quercetin in mice

The study was aimed at evaluating the 28-day repeated dose oral toxicity of onion skin quercetin (OSQ) in mice. Twenty-five mice were divided into five groups of 5 mice each. Group 1 served as the control, and groups 2 and 3 received OSQ at 95 mg/kg and 190 mg/kg, respectively, while groups 4 and 5 received OSQ at 380 mg/kg for 28 consecutive days. Mice in groups 1–4 were euthanized on day 29, while the mice in group 5 were left for 14 days without treatment before euthanasia. The kidneys and liver were processed for light microscopy, while the levels of AST, ALT, albumin, total protein concentration, cholesterol, creatinine, urea, and electrolyte were determined from the serum. A significant increase in serum albumin and total protein concentration was observed in mice that received 95 mg/kg OSQ (5.34 and 20.76) when compared with the control (2.01 and 5.61) at P < 0.05. Serum cholesterol and creatinine levels of mice that received 95 mg/kg OSQ (380.37 and 1.38) significantly increased when compared with the control (219.35 and 0.83) at P < 0.05. A significant increase in right kidney index was observed in mice that received OSQ at 190 mg/kg (0.61) when compared with the control mice (0.45) at P < 0.05. There was no significant change in the levels of catalase, glutathione reductase, superoxide dismutase, and malondialdehyde of mice that received OSQ at 95 mg/kg, 190 mg/kg, and 380 mg/kg when compared with the control mice. The kidney of mice that receive 190 mg/kg and 380 mg/kg OSQ for 28 days showed distorted glomeruli and degenerating convoluted tubules. In conclusion, long-term (28 days) administration of OSQ at a dose of 190 mg/kg and above could lead to renal and liver injury.