Synthesis and SAR study of novel diimide skeleton compounds with the anti-inflammatory activities in vitro and in vivo

Amide bonds widely exist in the structure of natural products and drugs, and play an important role in biological activities. However, due to the limitation of synthesis conditions, there are few studies on biscarbonyl diimides. In this paper, a series of new compounds with diimide skeleton were synthesized by using CDI and NaH as condensation agents. The anti-inflammatory activity and cytotoxicity of the compound in RAW264.7 macrophages were evaluated by ELISA and MTT experiments. The results showed that these compounds had good anti-inflammatory activity in vitro, and the IC50 of compound 4d on inflammatory factors IL-6 and TNF-α reached 1.59 μM and 15.30 μM, respectively. Further structure–activity relationship showed that biscarbonyl diimide and unsaturated double bond played a major role in the anti-inflammatory activity. In addition, compound 4d can alleviate acute lung injury (ALI) induced by LPS in vivo, reduce alveolar cell infiltration, and decrease the expression of ALI inflammatory factors. At the same time, compound 4d can significantly improve the survival rate of LPS-induced sepsis in mice. In short, the design and synthesis of the diimide skeleton provides a potential lead compound for the treatment of inflammatory diseases, and also provides a new idea for the design of amide compounds.