Protocatechuic acid attenuates lipolysaccharide-induced acute lung injury

Protocatechuic acid (PCA) is a major metabolite of anthocyanins. It has numerous pharmacological effects, including anti-inflammatory, antioxidant, and antitumoral activities. In the present study, we investigated the in vivo protective effect of PCA on acute lung injury (ALI) induced by lipolysaccharide (LPS) in mice. We treated mice with PCA 1 h before the intratracheal (i.n.) administration of LPS. The pulmonary injury severity was evaluated 6 h after LPS administration. We found that pretreatment with a 30 mg/kg of PCA markedly attenuated the LPS-induced histological alterations in the lung. In addition, PCA inhibited the production of several inflammatory cytokines, including tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), and IL-6, at 6 h in the bronchoalveolar lavage fluid (BALF) after LPS challenge. Furthermore, PCA significantly reduced the number of total cells, neutrophils, and macrophages in the BALF, and it significantly decreased the wet/dry weight (W/D) ratio of lungs and the protein concentration in the BALF. Additionally, Western blotting showed that PCA efficiently blunted nuclear factor-kappa B (NF-κB) activation by inhibiting the degradation and phosphorylation of IκBα, as well as the translocation of p65 from cytoplasm to the nucleus. In conclusion, these results indicate that PCA was highly effective in inhibiting acute lung injury (ALI) and may be a promising potential therapeutic reagent for ALI treatment. PCA may utilize the NF-κB pathway to attenuate the nonspecific pulmonary inflammation induced by LPS administration.