Inhaled 1,8‐Cineole Reduces Inflammatory Parameters in Airways of Ovalbumin‐Challenged Guinea Pigs

: Eucalyptol, also known as 1,8‐cineole, is a monoterpene traditionally used to treat respiratory disorders due to its secretolytic properties. In addition to its myorelaxant effects, it also has anti‐inflammatory actions in vitro. In this study, we aimed to evaluate the efficacy of acute treatment with 1,8‐cineole on reducing airway inflammatory parameters. Ovalbumin (OVA)‐sensitized guinea pigs were submitted to antigenic challenge (OVA) with or without pre‐treatment with a single dose of 1,8‐cineole administered by inhalation. Airway inflammatory parameters were reduced or absent in 1,8‐cineole‐treated animals as compared with untreated guinea pigs. Acute treatment with 1,8‐cineole impaired the development of airway hyperresponsiveness to carbachol in isolated tracheal rings. Levels of the pro‐inflammatory cytokines TNFα and IL‐1β was lower in bronchoalveolar lavage fluid (BALF) of 1,8‐cineol‐treated guinea pigs than in untreated animals. 1,8‐Cineole impaired the OVA‐induced increase of the myeloperoxidase activity in BALF. 1,8‐Cineole also prevented the reduction of the mucociliary clearance induced by the antigen presentation. The present investigation provides evidence that inhaled 1,8‐cineole prevents hyperresponsiveness and inhibits inflammation in airways of ovalbumin‐challenged guinea pigs.