Our experimental results showed that OPD effectively alleviated pulmonary edema and lung capillary barrier injury and potently regulated the levels of inflammatory mediators, such as ROS, MPO, TNF-α, IL-1β, IL-6, iNOS, and COX-2, which may be the main reason why OPD alleviated LPS-induced ALI disease. Here, MPO is linked to acute respiratory distress syndrome.