Design, synthesis, and biological evaluation of oridonin derivatives as novel NLRP3 inflammasome inhibitors for the treatment of acute lung injury

Acute lung injury (ALI) is a severe respiratory disorder closely associated with the excessive activation of the NLRP3 inflammasome. Oridonin ( Ori ), a natural diterpenoid compound, had been confirmed as a specific covalent NLRP3 inflammasome inhibitor, which was completely different from that of MCC950 . However, the further clinical application of Ori was limited by its weak inhibitory activity against NLRP3 inflammasome (IC 50 = 1240.67 nM). Fortunately, through systematic structure-optimization of Ori , D6 demonstrated the enhancement of IL-1β inhibitory activity (IC 50 = 41.79 nM), which was better than the parent compound Ori . Then, by using SPR, molecular docking and MD simulation, D6 was verified to directly interact with NLRP3 via covalent and non-covalent interaction. The further anti-inflammatory mechanism studies were revealed that D6 could inhibit the activation of NLRP3 inflammasome without affecting the initiation phase of NLRP3 inflammasome activation, and D6 was a broad-spectrum and selective NLRP3 inflammasome inhibitor. Finally, D6 demonstrated a favorable therapeutic effect on LPS-induced ALI in mice model, and the potent pharmacodynamic effect of D6 was correlated with the specific inhibition of NLRP3 inflammasome activation in vivo . Thus, D6 is proved as a potent NLRP3 inhibitor, and has the potential to develop as a novel anti-ALI agent.