Protective effect of quercetin against 5-fluorouracil-induced cardiac impairments through activating Nrf2 and inhibiting NF-κB and caspase-3 activities

5-Fluorouracil (5-FU) is a chemotherapy used to treat many types of cancer. Cardiotoxicity is one of the common drawbacks of 5-FU therapy. Quercetin (Qu) is a bioflavonoid with striking biological activities. This research aimed to assess the ameliorative effect of Qu against 5-FU-mediated cardiotoxicity. Thirty-five rats were allocated into five groups: control group (normal saline), 5-FU group (30 mg/kg, intraperitoneally), Qu group (50 mg/kg, oral), 25 mg/kg Qu+5-FU group, and 50 mg/kg Qu+5-FU. The experimental animals were received the above-mentioned drugs for 21 days. Results showed that 5-FU significantly elevated creatine kinase, lactate dehydrogenase, serum cholesterol and triglyceride, and upregulated troponin and renin mRNA expression. Additionally, cardiac oxidant/antioxidant imbalance was evident in elevated oxidants (malondialdehyde and nitric oxide) and depleted antioxidants (superoxide dismutase, catalase, glutathione peroxidase, and glutathione). 5-FU also downregulated the gene expression of nuclear factor erythroid 2-related factor 2. Furthermore, 5-FU significantly increased cardiac pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin-1 beta) and upregulated gene expression of nuclear factor kappa-B. 5-FU significantly enhanced cardiac apoptosis through upregulating caspase-3 expression and downregulating B-cell lymphoma 2. Immunohistochemical and histopathological examinations verified the above-mentioned findings. However, all these changes were significantly ameliorated in Qu pre-administered rats. Conclusively, Qu counteracted 5-FU-mediated cardiotoxicity through potent antioxidant, anti-inflammatory, and anti-apoptotic effects. Graphical abstract: [Figure not available: see fulltext.].