Sclareol is a natural fragrance compound that is used widely in the cosmetic and food industries. This study examined the effect of
sclareol on
lipopolysaccharide (LPS)-induced
acute lung injury (ALI) in mice. Mice were treated with
sclareol 1h before an intratracheal (I.T.) LPS challenge to induce an ALI model. The effects on lung tissue and
lung injury were evaluated 6h after LPS induction. Pretreatment with
sclareol noticeably improved the LPS-induced histological alterations and
edema in lung tissue.
Sclareol also inhibited the release of pro-inflammatory mediators. Differences in
nitric oxide (NO),
tumor necrosis factor alpha (TNF-α),
interleukin-1 beta (IL-1β),
IL-6, and
IL-10 were found in the bronchoalveolar lavage fluid (BALF) 6h after LPS-induced
lung injury. This study also found a reduced number of total cells and reduced
protein concentrations in the BALF. There were also changes in the pulmonary wet/dry (W/D) weight ratio,
antioxidant enzyme activity, and
myeloperoxidase activity in lung tissues.
Sclareol effectively blocked the phosphorylation of
mitogen-activated protein kinases (MAPKs) and impeded the
protein expression of
inducible nitric oxide synthase (iNOS) and
cyclooxygenase-2 (COX-2). The compound boosted the expression of
heme oxygenase-1 (HO-1) and inhibited the breakdown of
nuclear factor-kappa B (NF-κB) and inhibitor of kappa B (IκBα). To the best of the authors' knowledge, this study is the first to demonstrate that
sclareol effectively inhibits acute lung
edema, and the results suggest that
sclareol may be a potential agent for the treatment of ALI. The potential therapeutic benefits may include the attenuation of LPS-induced
pulmonary inflammation due to
sclareol's effects on several pathways, including NF-κB, MAPKs and HO-1, as well as the regulation of
antioxidant enzyme activity.