Beyond Traditional Structure-Based Drug Design: The Role of Iron Complexation, Strain, and Water in the Binding of Inhibitors for Hypoxia-Inducible Factor Prolyl Hydroxylase 2.

A combination of structure-based drug design and medicinal chemistry efforts led us from benzimidazole-2-carboxamide with modestly active hypoxia-inducible factor prolyl hydroxylase 2 inhibition to certain benzimidazole-2-pyrazole carboxylic acids that were more potent as well as orally efficacious stimulators of erythropoietin secretion in our in vivo mouse model. To better understand the structure-activity relationship, it was necessary to account for (i) the complexation of the ligand with the active site Fe, (ii) the strain incurred by the ligand upon binding, and (iii) certain key water interactions identified by a crystal structure analysis. With this more complete computational model, we arrived at an overarching paradigm that accounted for the potency differences between benzimidazole-2-carboxamide and benzimidazole-2-pyrazole carboxylic acid enzyme inhibitors.

Prolyl hydroxylase inhibition corrects functional iron deficiency and inflammation-induced anaemia in rats.

Background And Purpose: Small-molecule inhibitors of prolyl hydroxylase (PHD) enzymes are a novel target for the treatment of anaemia and functional iron deficiency (FID). Other than being orally bioavailable, the differentiation of PHD inhibitors from recombinant human erythropoietin (rhEPO) has not been demonstrated.

Experimental Approach: JNJ-42905343 was identified and characterized as a novel inhibitor of PHD and its action was compared with rhEPO in healthy rats and in a rat model of inflammation-induced anaemia and FID [peptidoglycan-polysaccharide (PGPS) model].

Pharmacological characterization of 1-(5-chloro-6-(trifluoromethoxy)-1H-benzoimidazol-2-yl)-1H-pyrazole-4-carboxylic acid (JNJ-42041935), a potent and selective hypoxia-inducible factor prolyl hydroxylase inhibitor.

The hypoxia-inducible factor (HIF) prolyl hydroxylase (PHD) enzymes represent novel targets for the treatment of anemia, ulcerative colitis, and ischemic and metabolic disease inter alia. We have identified a novel small-molecule inhibitor of PHD, 1-(5-chloro-6-(trifluoromethoxy)-1H-benzoimidazol-2-yl)-1H-pyrazole-4-carboxylic acid (JNJ-42041935), through structure-based drug design methods. The pharmacology of JNJ-42041935 was investigated in enzyme, cellular, and whole-animal systems and was compared with other compounds described in the literature as PHD inhibitors.

Benzimidazole-2-pyrazole HIF Prolyl 4-Hydroxylase Inhibitors as Oral Erythropoietin Secretagogues.

HIF prolyl 4-hydroxylases (PHD) are a family of enzymes that mediate key physiological responses to hypoxia by modulating the levels of hypoxia inducible factor 1-α (HIF1α). Certain benzimidazole-2-pyrazole carboxylates were discovered to be PHD2 inhibitors using ligand- and structure-based methods and found to be potent, orally efficacious stimulators of erythropoietin secretion in vivo.

IL-7 gene therapy in aging restores early thymopoiesis without reversing involution.

Thymic involution begins early in life and continues throughout adulthood, resulting in a decreased population of naive T cells in the periphery and a reduced ability to fight off newly encountered infectious diseases. We have previously shown that the first step of thymopoiesis is specifically blocked in aging. This block at the DN1 to DN2 transition and the subsequent loss of thymic output in old age mirrors the changes seen in IL-7-deficient mice, and it is hypothesized that decreased intrathymic IL-7 is involved in age-related thymic involution.