Malathion is a potent organophosphate insecticide that inhibits acetylcholinesterase (AChE) enzyme. Our experimental objective was to investigate the beneficial effects of diallyl sulphide (DAS) and thymoquinone (TQ) against malathion-induced oxidative stress in rat cerebral, hepatic, and renal tissues. For 30 days, rats received corn oil alone (negative control) or malathion by intragastric gavage (200 mg/kg daily), either alone (positive control) or combined with oral DAS (200 mg/kg daily) or TQ (10 mg/kg daily) (treatment groups). Later, blood samples were collected via direct cardiac puncture and tissue samples were obtained for biochemical analysis. Malathion administration was associated with significant increases (p < 0.05) in the serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, γ-glutamyl transferase, cholesterol, urea, creatinine, and 8-OHdG (DNA damage biomarker), as well as significant (p < 0.05) decreases in the serum levels of total proteins, albumin, triglycerides, and AChE. Moreover, it significantly increased the tissue concentrations of malondialdehyde and nitric oxide and reduced tissue glutathione concentration and activities of antioxidant enzymes (glutathione peroxidase, superoxide dismutase, and catalase). Treatment of malathion-intoxicated rats with DAS or TQ significantly minimized these biochemical and oxidative effects with more frequent reversal to normal ranges of serum biomarkers, tissue oxidative markers, and antioxidant enzymes in the TQ group. In conclusion, treatment with DAS or TQ ameliorated the biochemical and oxidative effects of malathion, probably through reducing the generation of reactive oxygen and nitrogen radicals, as well as enhancing the antioxidant defense mechanisms.
Keywords: Antioxidants; DNA damage; Diallyl sulphide; Malathion; Nigella sativa; Organophosphates; Thymoquinone.