OBJECTIVE To investigate the ameliorative effect of Pinelliae Rhizoma Praeparatum Cum Alumine and its effective components on inflammatory response in mice with acute lung injury (ALI).

METHODS A mice model of acute lung injury induced by lipopolysaccharide (LPS) was used as the in vivo animal model. The levels of inflammatory factors TNF-α, IL-6, and IL-1β, the total protein concentration, the number of inflammatory cells in bronchoalveolar lavage fluid, the ratio of lung wet weight to dry weight, and the pathological damage of lung tissues were taken as the evaluation indexes. RAW264.7 macrophages induced by LPS were used as the in vitro experimental model, with the mRNA levels of intracellular inflammatory factors TNF-α, IL-1β, and IL-6 as indicators, systematic solvent extraction and silica gel column chromatography were used to separate and screen the effective parts and components of Pinelliae Rhizoma Praeparatum Cum Alumine for treating acute lung injury. The component composition of the effective fractions was analyzed by mass spectrometry, the content of cyclic dipeptide components in the effective fraction was determined, and the anti-inflammatory activity of cyclic dipeptides was verified in vitro.

RESULTS The ethyl acetate extraction fraction obtained by extracting the supernatant of water extraction and ethanol precipitation of Pinelliae Rhizoma Praeparatum Cum Alumine (referred to as the ethyl acetate fraction for short) significantly improved the inflammatory response in mice with acute lung injury and significantly reduced the mRNA levels of TNF-α, IL-1β, and IL-6 in RAW264.7 cells induced by LPS. The Fr.1 fraction isolated from the ethyl acetate fraction by silica gel column chromatography had anti-inflammatory effects in vitro. Mass spectrometry determined the content of two main cyclic dipeptide components, cyclo-(Pro-Phe) and cyclo-(Pro-Val), in the Fr.1 fraction. After mixing these two cyclic dipeptide components in the molar ratio in the Fr.1 fraction and administering them in vitro, the results showed that the combination of these two cyclic dipeptide components could significantly inhibit the mRNA expression levels of TNF-α, IL-1β, and IL-6 in RAW264.7 cells induced by LPS.

CONCLUSION Cyclic dipeptide component is one of the main material basis categories for the anti-inflammatory effect of Pinelliae Rhizoma Praeparatum Cum Alumine.