Background. The inflammatory mechanisms occur with the highest prevalence in pulmonary pathology. In pharmaceutical industry, carrageenan is used as a pro-inflammatory agent when the activity of anti-inflammatory agents is tested. The oxidative stress represents the imbalance between pro-oxidants and antioxidants which can lead to the activation of the oxidative mechanisms with noxius potential to the body. In experimental studies, quercetin is the most active flavonoid, having the highest anti-inflammatory and antioxidant effects. Curcumin has antioxidant effects that are similar to those of the standard antioxidants and exerts direct anti-inflammatory activity.

Aims. The aim of this study is to determine the antioxidant effects of quercetin and curcumin on a carrageenan-induced pleural inflammation.

Methods. Eight groups of adult male rats were used: Ia and Ib -control groups, IIa and IIb -with carrageenan administration, IIIa and IIIb -with curcumin and carrageenan, IVa and IVb -with quercetin and carrageenan administration. Blood and lung samples were taken at 4 hours (Ia, IIa, IIIa, IVa groups) and at 24 hours (Ib, IIb, IIIb, IVb groups) after carrageenan administration.

Results. In serum, at 4 and at 24 hours, curcumin and quercetin showed protective effects, reducing the oxidative stress (malondialdehyde significantly decreased) and stimulating the antioxidant protection (ceruloplasmin and glutathione significantly increased) in rats with administration of these substances, in comparison to the group that received only carrageenan. In the lungs, at 4 hours, the oxidative stress was significantly reduced only in the rats that received quercetin (malondialdehyde significantly decreased), modifications that were not observed at 24 hours.    

Conclusions. In serum, curcumin presented higher antioxidant effects, compared to quercetin. In lungs, quercetin administration showed superior beneficial effects, but only temporarily.


pleural inflammation, oxidative stress, carrageenan, curcumin, quercetin