Recent Developments of p38α MAP Kinase Inhibitors as Anti-inflammatory Agents Based on the Imidazole Scaffolds

Rheumatoid arthritis (RA) and other chronic inflammatory diseases are always the major therapeutic challenges. Recent research efforts provided new insights into the molecular basis of these diseases and new opportunities for developing improved anti-inflammatory drugs. The p38 mitogen-activated protein (MAP) kinase plays a central role in the regulation of the biosynthesis and release of several proinflammatory cytokines including tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta). Hence, inhibition of the p38 MAP kinase is regarded as a promising therapeutic strategy for controlling inflammatory diseases. A diverse range of p38 alpha MAP kinase inhibitors have been developed as potential anti-inflammatory agents, and some of them have entered the phase II clinical trials. The imidazole derivatives are known as competitive inhibitors at the ATP binding site of the p38 alpha MAP kinase. Modifications on the imidazole scaffold have led to a large amount of potent p38 alpha MAP kinase inhibitors. This review will summarize the developments of small molecule p38 alpha MAP kinase inhibitors based on the imidazole core scaffolds in recent 10 years. Variations at the N1, C2, C4 and C5 positions of imidazole were introduced, and the structure-activity relationships of these imidazole inhibitors were also discussed.