Modulatory role of dose-dependent quercetin supplemented diet on behavioral and anti-oxidant system in <i>Drosophila melanogaster</i> model

Background: Quercetin is an abundant bio-flavonoid in foods having several biological activities including anti-oxidant properties. However, the toxicity of quercetin may limit its use. Therefore, screening a graded dose of quercetin may be an important step in its use as a dietary supplement. Hence, the effects of graded doses of quercetin on the survival, locomotive behavior and oxidant-antioxidant system in D. Melanogaster was investigated.Methods: A Survival assay was conducted by feeding 50 fruit flies per vial with 50-400 mg/g quercetin-diet for 14 days. For behavioral and biochemical studies, flies were divided into 4 vials (50 flies each) 0, 100, 200 and 300 mg/g quercetin-diet. Flies were treated with vehicle or quercetin for 7 days. Behavioral assessment of negative geotaxis was determined from the climbing activities of flies. Finally, flies were killed, homogenized and centrifuged for supernatant for the assay of Catalase (CAT), Superoxide dismutase (SOD), Glutathione (GSH), Malondialdehyde (MDA) and Total thiol.Results: Quercetin treated groups showed a dose-dependent significant decrease (p<0.001) in survival rate. Climbing activity was unaltered at 100 mg but significantly (p<0.05) reduced at 200 and 300mg quercetin. Total thiol was not significantly altered (p>0.05) across the groups, MDA was reduced (p<0.05) at 300 mg compared to control, CAT activity was significantly increased (p<0.05) at 100-200 mg compared to control while GSH and SOD at 100-200 mg of quercetin increased.Conclusion: Quercetin showed better antioxidant activity at lower doses and adversely affected the climbing behavior and survival rate at higher doses. Therefore, quercetin use should be dose modulated and used with caution.