MyD88-IN-3 is an orally active, selective MyD88 inhibitor that specifically targets the TIR domain of MyD88 (KD= 28.5 μM). It prevents MyD88 self-aggregation and its interaction with TLRs, thereby suppressing the activation of the MAPK and NF-κB pathways. MyD88-IN-3 exhibits significant anti-inflammatory effects and effectively alleviates symptoms of acute lung injury in CLP (cecal ligation and puncture) and LPS (lipopolysaccharide)-induced ALI models. This compound is valuable for ALI research.

MyD88-IN-3 exhibits potent anti-inflammatory effects, significantly inhibiting IL-6 secretion in mouse macrophages J774A.1 (IC 50 = 1.32 μM) and PMA-induced differentiated human macrophages THP-1 (IC 50 = 0.75 μM). At a concentration of 10 μM, with 2-hour pretreatment followed by co-treatment with 0.5 μg/mL LPS for 30 minutes, this compound restores LPS-induced reduction in IκBα expression levels in J774A.1 macrophages while markedly decreasing phosphorylation of p38 and inhibiting phosphorylation of JNK and p65. It also inhibits LPS-induced MAPK pathway activation, leading to nuclear translocation of c-Jun. At concentrations of 5 μM and 10 μM, MyD88-IN-3 inhibits homodimerization of MyD88 in J774A.1 cells. Additionally, at 10 μM for 2 hours, it suppresses the interaction between MyD88 and TLR4 in J774A.1 cells. Furthermore, at 10 μM for 4 hours, MyD88-IN-3 enhances the thermal stability of MyD88, retaining approximately 50% at 64℃. The compound binds effectively to the TIR domain (K D = 28.5 μM) but shows no binding affinity for the DD domain (K D = 1.32 M).

MyD88-IN-3 demonstrates good safety in SD rats when administered orally at doses of 500 mg/kg and 1000 mg/kg daily for 10 consecutive days. Additionally, pretreatment with MyD88-IN-3 at 20 mg/kg orally for 6 hours alleviates sepsis-induced acute lung injury in C57BL/6 mice. Similarly, a 30-minute pretreatment with the same dosage mitigates LPS-induced acute lung injury in C57BL/6 mice.