Protective effects of Nigella sativa oil and thymoquinone against toxicity induced by the anticancer drug cyclophosphamide

Constituents of the Nigella sativa seed are reported to possess potent antioxidant effects. Treatment with anticancer drugs such as cyclophosphamide (CTX) is associated with significant toxicity due to over-production of reactive oxygen species, resulting in increased levels of oxidative stress. The aim of this study is to test whether or not N. sativa L oil (NSO) or its active ingredient, thymoquinone (TQ), can reduce CTX-induced toxicity. Male albino rats were treated with intraperitoneal administration of phosphate buffered saline (PBS) or 200 mg/Kg CTX followed by intragastric administration of NSO or TQ on alternate days for 12 days. Administration of NSO and TQ was initiated 6 h before or after CTX injection. Twenty-four hours after the last NSO and TQ treatment, blood and liver were harvested to analyse toxicity-related parameters. Treatment with CTX induced significant toxicity as shown by decrease in haemoglobin concentration and increases in blood sugar levels, activities of liver enzymes, bilirubin, urea, creatinine, lipids (triglyceride, cholesterol and low-density lipoprotein (LDL)-cholesterol) and lipid peroxidation in the liver. Treatment with NSO or TQ induced significant reduction in overall toxicity. The antitoxic effects of NSO and TQ were associated with induction of antioxidant mechanisms. These results suggest that administration of NSO or TQ can lower CTX-induced toxicity as shown by an up-regulation of antioxidant mechanisms, indicating a potential clinical application for these agents to minimise the toxic effects of treatment with anticancer drugs.