QUERCETIN AND CURCUMIN ATTENUATE GASOLINE FUME-INDUCED OXIDATIVE STRESS AND MODULATE ANTIOXIDANT ENZYME ACTIVITIES IN MALE WISTAR RATS

Abstract

Background: Inhalation of gasoline fumes constitutes a significant occupational and environmental health hazard capable of inducing oxidative stress and depleting endogenous antioxidant defenses in exposed individuals. Quercetin and curcumin are naturally occurring dietary polyphenols with well-established antioxidant and anti-inflammatory properties that may offer protective benefits against such toxicant-induced biochemical disruption. Objective: This study investigated the ameliorative effects of quercetin and curcumin on serum oxidative stress markers and antioxidant enzyme activities in male Wistar rats subjected to sub-chronic leaded gasoline fume inhalation. Methods: Sixty (60) adult male albino Wistar rats were randomly assigned into seven groups. Group A served as the negative control. Groups B1 and B2 were exposed to 20 ml leaded gasoline fumes (one hour daily) for two weeks, then treated with quercetin (50 mg/kg) and curcumin (50 mg/kg) respectively by oral gavage for one week. Groups C1 and C2 underwent three weeks of gasoline fume exposure followed by two weeks of quercetin and curcumin treatment respectively. Groups D1 and D2 were exposed for two and three weeks respectively with no antioxidant treatment. Serum malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), and catalase were measured using standard spectrophotometric methods. Data were analysed using GraphPad Prism 9.5.1 with one-way ANOVA followed by Fisher's LSD post-hoc test and paired t-test for body weight comparisons; significance was set at p<0.05. Results: Gasoline fume exposure significantly (p<0.05) elevated serum MDA and significantly reduced SOD, catalase, and GSH in the untreated exposure groups (D1 and D2), with three-week exposure producing greater derangement than two-week exposure. Post-exposure quercetin and curcumin supplementation significantly attenuated MDA elevation and restored antioxidant enzyme activities towards control values, with quercetin demonstrating superior recovery across most biochemical parameters compared to curcumin at equivalent dose. Conclusion: Sub-chronic leaded gasoline fume inhalation produces duration-dependent oxidative stress in male Wistar rats, and post-exposure supplementation with quercetin or curcumin at 50 mg/kg significantly mitigates these effects. Quercetin demonstrated greater antioxidant efficacy than curcumin under the conditions studied, supporting its therapeutic potential against petroleum fume-induced oxidative injury.