Design, synthesis and structure-activity relationship studies of 4-indole-2-arylaminopyrimidine derivatives as anti-inflammatory agents for acute lung injury.

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS), a clinically high mortality disease, has not been effectively treated till now, and the development of anti-acute lung injury drugs is imminent. Acute lung injury was efficiently treated by inhibiting the cascade of inflammation, and reducing the inflammatory response in the lung. A series of novel compounds with highly efficient inhibiting the expression of inflammatory factors were designed by using 4-indolyl-2-aminopyrimidine as the core skeleton. Totally eleven 4-indolyl-2-arylaminopyrimidine derivatives were designed and synthesized. As well, the related anti-ALI activity of these compounds was evaluated. Compounds 6c and 6h showed a superior activity among these compounds, and the inhibition rate of IL-6 and IL-8 release ranged from 62% to 77%, and from 65% to 72%, respectively. Furthermore, most of compounds had no significant cytotoxicity in vitro. The infiltration of inflammatory cells into lung tissue significantly reduced by using compound 6h (20 mg/kg) in the ALI mice model, which achieved the effect of protecting lung tissue and improving ALI. In addition, the inflammatory response was inhibited by using compound 6h through inhibiting phosphorylation of p-38 and ERK in MAPK signaling pathway, and resulted in protective effect on ALI. These data indicated that compound 6h showed good anti-inflammatory activity in vitro and in vivo, which was expected to become a leading compound for the treatment of ALI.