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Heme oxygenase (HO) is a cytoprotective enzyme that can be overexpressed in some pathological conditions, including certain cancers. In this work, novel imidazole derivatives were designed and synthesized as inhibitors of heme oxygenase-1 (HO-1) and heme oxygenase-2 (HO-2). In these compounds the imidazole ring, crucial for the activity, is connected to a hydrophobic group, represented by aryloxy, benzothiazole, or benzoxazole moieties, by means of alkyl or thioalkyl chains of different length. Many of the tested compounds were potent and/or selective against one of the two isoforms of HO. Furthermore, most of the pentyl derivatives showed to be better inhibitors of HO-2 with respect to HO-1, revealing a critical role of the alkyl chain in discriminating between the two isoenzymes. Compounds which showed the better profile of HO inhibition were selected and tested to evaluate their cytotoxic properties in prostate and breast cancer cell lines (DU-145, PC3, LnCap, MDA-MB-231, and MCF-7). In these assays, aryloxyalkyl derivatives resulted more cytotoxic than benzothiazolethioalkyl ones; in particular compound 31 was active against all the cell lines tested, confirming the anti-proliferative properties of HO inhibitors and their potential use in the treatment of specific cancers., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

A novel series of aryloxyalkyl derivatives of imidazole and 1,2,4-triazole, 17-31, was designed and synthesized as inhibitors of heme oxygenase-1 (HO-1) and heme oxygenase-2 (HO-2). Some of these compounds were found to be good inhibitors of HO-1, in particular those carrying an imidazole moiety as azolyl group and a 3-bromo or 4-iodophenyl as aryl moiety. The most potent compounds 6 and 30 were selected and studied for their antitumor properties in a model of LAMA-84 R cell line overexpressing HO-1 and resistant to imatinib mesylate (IM), a tyrosine-kinase inhibitor used in the treatment of multiple types of cancer, most notably Philadelphia Chromosome positive (Ph(+)) Chronic Myelogenous Leukemia (CML). Results show that both 6 and 30 sensitized LAMA-84 R cell line to antitumor properties of IM., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Imidazole-based compounds previously synthesized in our laboratory were selected and reconsidered as inhibitors of heme oxygenase-1 obtained from the microsomal fractions of rat spleens. Most of tested compounds were good inhibitors with IC(50) values in the low micromolar range. Compounds were also assayed on membrane-free full-length recombinant human heme oxygenase-1; all tested compounds were unable to interact with human heme oxygenase-1 at 100 μm concentrations with the exception of compounds 11 and 13 that inhibited the enzyme of 54% and 20%, respectively. The binding of the most active compound 11 with heme or heme-conjugated human heme oxygenase-1 was also examined by spectral analyses. When heme was not conjugated to human heme oxygenase-1, compound 11 caused changes in the heme spectrum only at concentration 50-fold (100 μm) higher than that required to inhibit rat heme oxygenase-1; when heme was conjugated to human heme oxygenase-1, compound 11 was able to form a heme-compound 11 complex also at low micromolar concentrations. To obtain information on the binding mode of the tested compounds with enzyme, docking studies and pharmacophore analysis were performed. Template docking results were in agreement with experimental inhibition data and with a structure-based pharmacophoric model. These data may be exploitable to design new OH-1 inhibitors., (© 2012 John Wiley & Sons A/S.)

Abstract: We previously described a series of imidazole-based inhibitors substituted at N-1 with an arylethanone chain as interesting inhibitors of neuronal nitric oxide synthase (nNOS), endowed with good selectivity vs endothelial nitric oxide synthase (eNOS). As a follow up of these studies, several analogs characterized by the presence of substituted imidazoles or other mono or bicyclic nitrogen-containing heterocycles instead of simple imidazole were synthesized, and their biological evaluation as in vitro inhibitors of both nNOS and eNOS is described herein. Most of these compounds showed improved nNOS and eNOS inhibitory activity with respect to reference inhibitors. Selected compounds were also tested to analyze their antioxidant properties. Some of them displayed good capacity to scavenge free radicals and ability to reduce lipid peroxidation. [Copyright &y& Elsevier]