The significance of thymoquinone administration on liver toxicity of diazinon and cholinesterase activity; a recommendation for prophylaxis among individuals at risk.

BACKGROUND: Diazinon (DZN), a widely used chemical herbicide for controlling agricultural pests, is an important organophosphorus pesticide and an environmental pollutant which induces toxic effects on living organisms during long-term exposure. Thymoquinone (TQ) is a phytochemical bioactive compound with antioxidant and anti-inflammatory properties. We aimed to evaluate the protective effects of TQ against DZN-induced hepatotoxicity through alleviating oxidative stress and enhancing cholinesterase (ChE) enzyme activity. METHODS: Rats were randomly divided into six groups (n = 8); a negative control group receiving corn oil; a group only receiving DZN (20 mg/kg/day); a group treated with TQ (10 mg/kg/day), and three treatment groups as TQ + DZN, receiving different doses of TQ (2.5, 5, and 10 mg/kg/day). All experimental animals were orally treated for 28 consecutive days. The levels of superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and lactic acid dehydrogenase (LDH) were determined. In addition, ChE activity and histopathological changes were evaluated. RESULTS: The results showed that DZN decreased GSH level (p < 0.01) and SOD activity (p < 0.01) in parallel to an increase in MDA level (p < 0.01) and increased the activity of AST, ALT, ALP, and LDH (p < 0.01) in comparison to the negative control group. Our findings demonstrated that TQ administration could diminish hepatotoxicity and reduce oxidative damage in DZN-treated rats, which could be linked to its antioxidant and free radical scavenging properties. It was also observed that TQ 10 mg/kg remarkably increased the activity of acetylcholinesterase, butyrylcholinesterase, and SOD enzymes, elevated GSH, decreased MDA, and reduced pathological alternations of the liver induced by DZN. CONCLUSION: Thymoquinone 10 mg/kg increased the activity of plasma and blood cholinesterases and reduced DZN-induced alternations of the liver. Improvement of butyryl- and acetylcholinesterase activity suggests that maybe TQ supplement could be beneficial as pre-exposure prophylaxis among farm workers spraying pesticides.

Protective effect of thymoquinone, the main component of Nigella Sativa, against diazinon cardio-toxicity in rats.

Several studies have shown that oxidative stress and cell damage can occur at very early stages of diazinon (DZN) exposure. The present study was designed to determine the beneficial effect of thymoquinone (Thy), the main component of Nigella sativa (black seed or black cumin), against DZN cardio-toxicity in rats. In the present experimental study, 48 male Wistar rats were randomly divided into six groups: control (corn oil gavages), DZN gavages (20 mg/kg/day), Thy gavages (10 mg/kg/day) and Thy + DVN gavages (2.5, 5 and 10 mg/kg/day). Treatments were continued for 28 days, then the animals were anesthetized by ether and superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), lactate dehydrogenize (LDH) and glutathione peroxide (GPX) activity was evaluated. In addition, glutathione (GSH) and malondialdehyde (MDA) the heart tissue and creatinephosphokinase-MB (CPK-MB) and troponin (TPI) levels and cholinesterase activity in the blood were evaluated. DZN-induced oxidative damage and elevated the levels of the cardiac markers CK-MB, TPI, MDA and LDH and decreased SOD, CAT and cholinesterase activity and GSH level compared with the control group. Treatment with Thy reduced DZN cardio-toxicity and cholinesterase activity. The success of Thy supplementation against DZN toxicity can be attributed to the antioxidant effects of its constituents. Administration of Thy as a natural antioxidant decreased DZN cardio-toxicity and improved cholinesterase activity in rats through the mechanism of free radical scavenging.