1-O-Acetylbritannilactone exerts anti-inflammatory and anti-MUC5AC effects by targeting PKC-α and downregulating the SRC/EGFR/MAPK signaling pathway.

MUC5AC is an important component of mucins, which is often disproportionately increased in response to cigarette smoke and allergens, thereby increasing health problems. As a traditional Chinese medicine, Inula japonica Thunb. is used mainly to treat cough and phlegm. 1-O-Acetylbritannilactone (ABL), one of the main ingredients in I. japonica, may be an anti-inflammatory and anti-MUC5AC drug candidate. ABL significantly decreased the production of NO and the mRNA expression of IL-1β, IL-6, TNF-α, and iNOS in LPS-stimulated RAW264.7 cells. Network pharmacology suggested that ABL might inhibit inflammation and MUC5AC expression, and EGFR, MAPK, SRC, and PKC-α might be key proteins involved. The results of molecular docking, molecular dynamics simulations, CETSA and MST suggested that ABL interacted with PKC-α, indicating that PKC-α was a target of ABL. ABL reduced the expression of the SRC/EGFR/MAPK signaling pathway in PMA-induced NCI-H292 cells and LPS-stimulated RAW264.7 cells. In animal experiments, ABL significantly ameliorated COPD in mice by improving pulmonary function, suppressing oxidative stress, and decreasing inflammatory cell infiltration and mucus production in lung tissue. The results of the phenol red test showed that ABL had a significant expectorant effect. In conclusion, ABL exhibited anti-inflammatory and anti-MUC5AC effects by targeting PKC-α and downregulating the SRC/EGFR/MAPK signaling pathway. This study revealed that ABL is a natural candidate molecule with anti-inflammatory and expectorant effects.