Discovery of triazolopyrimidine-based PDE8B inhibitors: exceptionally ligand-efficient and lipophilic ligand-efficient compounds for the treatment of diabetes.

PDE8B is a cAMP-specific isoform of the broader class of phosphodiesterases (PDEs). As no selective PDE8B inhibitors had been reported, a high throughput screen was run with the goal of identifying selective tools for exploring the potential therapeutic utility of PDE8B inhibition. Of the numerous hits, one was particularly attractive since it was amenable to rapid deconstruction leading to inhibitors with very high ligand efficiency (LE) and lipophilic ligand efficiency (LLE). These triazolopyrimidines were optimized for potency, selectivity and ADME properties ultimately leading to compound 42. This compound was highly potent and selective with good bioavailability and advanced into pre-clinical development.

Maximizing lipophilic efficiency: the use of Free-Wilson analysis in the design of inhibitors of acetyl-CoA carboxylase.

This paper describes the design and synthesis of a novel series of dual inhibitors of acetyl-CoA carboxylase 1 and 2 (ACC1 and ACC2). Key findings include the discovery of an initial lead that was modestly potent and subsequent medicinal chemistry optimization with a focus on lipophilic efficiency (LipE) to balance overall druglike properties. Free-Wilson methodology provided a clear breakdown of the contributions of specific structural elements to the overall LipE, a rationale for prioritization of virtual compounds for synthesis, and a highly successful prediction of the LipE of the resulting analogues. Further preclinical assays, including in vivo malonyl-CoA reduction in both rat liver (ACC1) and rat muscle (ACC2), identified an advanced analogue that progressed to regulatory toxicity studies.

Structure-guided inhibitor design for human acetyl-coenzyme A carboxylase by interspecies active site conversion.

Inhibition of acetyl-CoA carboxylases (ACCs), a crucial enzyme for fatty acid metabolism, has been shown to promote fatty acid oxidation and reduce body fat in animal models. Therefore, ACCs are attractive targets for structure-based inhibitor design, particularly the carboxyltransferase (CT) domain, which is the primary site for inhibitor interaction. We have cloned, expressed, and purified the CT domain of human ACC2 using baculovirus-mediated insect cell expression system. However, attempts to crystallize the human ACC2 CT domain have not been successful in our hands. Hence, we have been using the available crystal structure of yeast CT domain to design human ACC inhibitors. Unfortunately, as the selectivity of the lead series has increased against the full-length human enzyme, the potency against the yeast enzyme has decreased significantly. This loss of potency against the yeast enzyme correlated with a complete lack of binding of the human-specific compounds to crystals of the yeast CT domain. Here, we address this problem by converting nine key active site residues of the yeast CT domain to the corresponding human residues. The resulting humanized yeast ACC-CT (yCT-H9) protein exhibits biochemical and biophysical properties closer to the human CT domain and binding to human specific compounds. We report high resolution crystal structures of yCT-H9 complexed with inhibitors that show a preference for the human CT domain. These structures offer insights that explain the species selectivity of ACC inhibitors and may guide future drug design programs.

Discovery of small molecule isozyme non-specific inhibitors of mammalian acetyl-CoA carboxylase 1 and 2.

Screening Pfizer's compound library resulted in the identification of weak acetyl-CoA carboxylase inhibitors, from which were obtained rACC1 CT-domain co-crystal structures. Utilizing HTS hits and structure-based drug discovery, a more rigid inhibitor was designed and led to the discovery of sub-micromolar, spirochromanone non-specific ACC inhibitors. Low nanomolar, non-specific ACC-isozyme inhibitors that exhibited good rat pharmacokinetics were obtained from this chemotype.

Review of recent acetyl-CoA carboxylase inhibitor patents: mid-2007-2008.

BACKGROUND: Acetyl-CoA carboxylase (ACC) is a biologic target that is receiving increased attention for the treatment of obesity and type 2 diabetes mellitus. Inhibition of this enzyme, either in transgenic mice or pharmacologically, has been shown to have beneficial effects on lab animals. METHOD: This review of the ACC inhibitor patent literature covers the period from mid-2007 to December 2008, during which time a total of 18 patents were published. CONCLUSION: These published patent applications include ACC inhibitors that inhibit the enzyme through modulation of the carboxyltransferase-domain, inhibitors that bind to the biotin carboxylase-domain and novel chemotypes whose mode of action was not disclosed. Furthermore, published patents claim the discovery of ACC2 isoform selective and ACC1/2 non-selective inhibitors.

Heteroatom-linked indanylpyrazines are corticotropin releasing factor type-1 receptor antagonists.

Low nanomolar corticotropin releasing factor type-1 (CRF(1)) receptor antagonists containing unique indanylamines were identified from the heteroatom-linked pyrazine chemotype. The most potent indanylpyrazine had a K(i)=11+/-1 nM. The oxygen-linked pyrazinyl derivatives were prepared through a copper-catalyzed coupling of a pyridinone to a bromo- or iodopyrazine.

Inhibitors of mammalian acetyl-CoA carboxylase.

Inhibition of acetyl-CoA carboxylase (ACC), with its resultant inhibition of fatty acid synthesis and stimulation of fatty acid oxidation, has the potential to favorably affect, in a concerted manner, a multitude of the cardiometabolic risk factors associated with diabetes, obesity, and the metabolic syndrome. Studies in ACC2 knockout mice and in experimental animals treated with isozyme-specific antisense oligonucleotides or with isozyme-nonselective ACC inhibitors have demonstrated the potential for treating metabolic syndrome through this modality. Co-crystallization of the biotin carboxylase and carboxyltransferase domains of eukaryotic ACC in the presence of substrates and inhibitors has revealed characteristics of the catalytic center that can be exploited in drug discovery. A variety of structurally diverse, mechanistically distinct classes of ACC inhibitors have been disclosed in the scientific and patent literature. Isozyme-nonselective ACC inhibitors may provide the optimal therapeutic potential. However, demonstration of the full potential of isozyme-selective inhibitors, once identified, should reveal advantages and liabilities associated with single isozyme inhibition.

Discovery of second generation quinazolinone non-nucleoside reverse transcriptase inhibitors of HIV-1.

An intensive research effort to identify potent, viable drugs for the management of acquired immunodeficiency syndrome (AIDS) resulted in the development of SUSTIVA (efavirenz), the first non-nucleoside reverse transcriptase inhibitor (NNRTI) approved by the FDA as a preferred first-line therapy. The search for NNRTIs that possess a broader activity spectrum against mutant viral forms of human immunodeficiency syndrome type-I reverse transcriptase culminated in the discovery that trifluoromethyl-containing quinazolin-2(1H)-ones possess potent activity as non-nucleoside reverse transcriptase inhibitors (NNRTIs). This chapter reviews the discovery and structure activity relationships that resulted in the identification and subsequent preclinical and clinical development of four quinazolinone NNRTIs at the DuPont Pharmaceuticals Company.