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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. [ABSTRACT FROM AUTHOR]

Abstract: 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 &y& Elsevier]

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]

Abstract: Diabetes mellitus is associated with a higher oxidative stress and reduced activity of the antioxidant defense system in different brain regions. Results from numerous studies reported impaired cognitive and neurochemical function in diabetic patients and streptozotocin induced diabetic rodents. It is well established that polyphenols exert potent antioxidant and protective functions. Based on recent findings, one potential target for the antioxidant/antinflammatory properties of polyphenols is the heme oxygenase (HO)-1 pathway. Among various compounds tested silibinin, the main component of silymarin, has been shown to possess a strong antioxidant effect in various experimental models; however a study on the possible neuroprotective effect of this compound on the brain of diabetic animals is currently lacking. Therefore, we studied and measured in lean mice (db/m) and knock out mice for the leptin receptors mice (db/db) the effect of silibinin on HO-1 protein levels, non proteic thiol groups, isoprostanes and 8-OH deoxyguanosine (markers of lipid peroxidation and DNA damage, respectively) in different brain regions. Our results showed that HO-1 is differently expressed in various brain regions in db/db mice when compared to lean animals. Furthermore, silibinin provides DNA protection and reduces oxidative stress in a brain specific area, in part via the activation of the HO system. Silibinin may provide a valid tool to counteract oxidative stress in the diabetic status in the central nervous system under diabetic condition. [Copyright &y& Elsevier]

Abstract: Human milk contains biological factors that are involved in a newborn''s growth and immune system regulation. By integrating standard biochemical experimental protocols with computational methods, the present study investigates the presence of heme oxygenase-1 (HO-1), a cytoprotective enzyme, in human milk at different levels of maturation and in milk formulae. Furthermore, we evaluated cytokine and glutathione S-transferase (GSH) levels. Samples were collected from colostrum (on Day 1 after birth), from transition milk (on Postdelivery Days 7 and 14) and from mature milk (on Day 30 after delivery) in 14 healthy women. HO-1 protein, GSH and cytokines levels were measured using enzyme-linked immunosorbent assay and flow cytometry. HO-1 protein levels were significantly higher in colostrum (1.33 ng/ml; 5th centile 0.92; 95th centile 2.38) and in transition milk at 14 days (0.97 ng/ml; 5th centile 0.87; 95th centile 1.45) than in mature milk (0.9 ng/ml; 5th centile 0.8; 95th centile 1.38). Levels of HO-1 in milk formulae were similar to those in colostrum. No significant differences in GSH content were observed in mature milk, transition milk and colostrum, whereas significantly higher GSH levels were observed in milk formulae. No significant levels of cytokines, with the exception of interleukin-8, were found. Computational studies on the possible interactions between HO-1 and CD91 were carried out by a battery of softwares, namely, GRAMM (version 1.03), DALI, CLUSTALW (version 2.0), PatchDock and FireDock, mutually counterchecking and validating each other. The computational results, the strong convergence (to the same “solution”) of which finally leads to an “experimental-like” character, showed that HO-1 may bind to CD91, thus suggesting its major role as a new chaperokine in immune response regulation. These findings, which connect and integrate biochemical data and computational data interpretation, represent a synergistic and powerful means of conducting biological research. [Copyright &y& Elsevier]

Pursuing previous researches on lipophilic conjugates of methotrexate, aimed at over-crossing a form of transport resistance shown by some tumor cell lines toward the drug, a new series of derivatives is described in which the drug α- and γ-carboxyl groups have been linked through amide bonds to short-chain α-alkylamino acids (4–6 carbon atoms). A specific NMR study was performed to delineate the stereochemistry of the conjugates. The inhibitory activity of these compounds against the target enzyme, (bovine liver) dihydrofolate reductase, and a sensitive (CCRF-CEM) and a transport-resistant tumor cell subline (CEM-MTX) were assessed. The conjugates showed the ability of retaining the same inhibitory activity also against the resistant cell subline, against which the parent drug was much less active than against the wild one; the α,γ-bis(hexyl) derivative was the most active term of the series. Docking studies are in agreement with the proposed mode of interaction of these conjugates with the human DHFR. [Copyright &y& Elsevier]