Eugenol dose-dependent improvement of pulmonary lesions in lipopolysaccharide acute lung injury

Background: Eugenol, a methoxyphenol component of clover oil, inhibits NF-κB activation induced by TNF-α in LPS-stimulated macrophages. Aim: The aim of the study was to evaluate the effects of different doses of eugenol on lung mechanics, histology and cytokines in LPS-injured lungs. Methods: 59 female BALB/c mice were randomly divided in 9 groups (n=5-8/group). Mice received intratracheally sterile saline solution (0.05 ml) or LPS (10 μg in 0.05 ml of saline); 6 h later they received sterile saline (0.2 ml) and Tween 1% (C, and L groups) or different doses of eugenol: 16, 65, 114, 160, 650 or 1140 mg/kg in saline (0.2 ml) and Tween 1% (LE1, LE2, LE3, LE4, LE5, LE6 and LE7 groups, respectively) by gavage. Mice were evaluated 24 h after receiving LPS. In another 18 mice [C=6, L=6, E=3 (saline followed by eugenol) and LE=3]; in these animals TNF-α and IL-1β were detected by ELISA in lung homogenates at 6 (C=3 and L=3) and 24 h (C=3, L=3, E=3 and LE=3) after LPS administration. One-way ANOVA followed by Tukey test was used (α=5%). Results: Static elastance, viscoelastic component of elastance and viscoelastic resistive pressure were higher in L group (33.05, 5.01 cmH 2 O/ml, and 1.00 cmH 2 O, respectively) than in C (22.13, 3.62 cmH 2 O/ml, and 0.71 cmH 2 O), accompanied by alveolar collapse and collagen fiber deposition; eugenol reduced the parameters in LE4 group (except alveolar collapse) and abolished them from LE5 (23.34, 3.62 cmH 2 O/ml, and 0.72 cmH 2 O) onwards. LE group showed smaller TNF-α and IL-1β levels than L mice. LE behaved similarly to C and E groups. Conclusion: Eugenol exhibits an in vivo anti-inflammatory dose-dependent action in LPS-induced lung injury. Supported by: CNPq, FAPERJ, MCT.