Sim-9

Sim-9 is a covalent allosteric inhibitor of the interferon regulatory factor 3 (IRF3). It covalently binds to the Cys222 residue of IRF3, causing a conformational change that blocks its interactions with TRIF, MAVS, and STING, thereby inhibiting IRF3 homodimerization and the type I interferon response. In mouse models of sepsis and acute pancreatitis, Sim-9 demonstrates significant anti-inflammatory, organ-protective, and survival benefits. This compound is applicable for research into inflammatory diseases.

Sim-9, at concentrations ranging from 2.5 to 10 μM, inhibits the interferon response triggered by the activation of TLRs, RLRs, and STING in a dose-dependent manner in murine RAW264.7 cells as well as human THP-1, HT-29, and A549 cells. At 5 μM over 0.5 to 6 hours, Sim-9 suppresses IRF3 phosphorylation in murine RAW264.7 cells activated through cGAS-STING, TLR3, or RIG-I pathways, without affecting TBK1 phosphorylation. Additionally, Sim-9 at 5 μM inhibits IRF3 homodimerization in murine RAW264.7 cells activated through these pathways.

In mouse models, Sim-9 (30-60 mg/kg; i.p.; single injection) demonstrates protective and anti-inflammatory properties in sepsis. Additionally, Sim-9 (30-60 mg/kg; i.p.; 1 injection/3 injections) reduces pancreatic edema and inflammation markers in acute pancreatitis.