High-Throughput Screening Strategy Identifies Allosteric, Covalent Human D-Amino Acid Oxidase Inhibitor.

Genome-wide association studies have linked polymorphisms in the gene G72 to schizophrenia risk in several human populations. Although controversial, biochemical experiments have suggested that the mechanistic link of G72 to schizophrenia is due to the G72 protein product, pLG72, exerting a regulatory effect on human D-amino acid oxidase (hDAAO) activity. In an effort to identify hDAAO inhibitors of novel mechanism of action, we designed a pLG72-directed hDAAO activity assay suitable for high-throughput screening (HTS). During assay development, we confirmed that pLG72 was an inhibitor of hDAAO. Thus, our assay employed an IC20 pLG72 concentration that was high enough to allow dynamic pLG72-hDAAO complexes to form but with sufficient remaining hDAAO activity to measure during an HTS. After conducting an approximately 150,000-compound HTS, we further characterized a class of compound hits that were less potent hDAAO inhibitors when pLG72 was present. Focusing primarily on compound 2: [2-(2,5-dimethylphenyl)-6-fluorobenzo[d]isothiazol-3(2H)-on], we demonstrated that these compounds inhibited hDAAO via an allosteric, covalent mechanism. Although there is significant interest in the therapeutic potential of compound 2: and its analogues, their sensitivity to reducing agents and their capacity to bind cysteines covalently would need to be addressed during therapeutic drug development.

Synthesis and SAR study of imidazoquinolines as a novel structural class of microsomal prostaglandin E2 synthase-1 inhibitors.

The imidazoquinoline derivative 1 was found as a novel mPGES-1 inhibitor. Optimization of 1 led to the identification of the 2-chlorophenyl group at the C(2)-position and the quinolone structure at the C(4)-position. Compound 33, the most potent synthesized compound, showed excellent mPGES-1 inhibition (IC(50)=9.1nM) with high selectivity (>1000-fold) over both COX-1 and COX-2.