Pubblicazione: A dinuclear biomimetic Cu complex derived from l-histidine: synthesis and stereoselective oxidations. Perrone ML, Salvadeo E, Lo Presti E, Pasotti L, Monzani E, Santagostini L, Casella L. Dalton Trans. 2017 Mar 21;46(12):4018-4029. doi: 10.1039/c7dt00147a.

Abstract:

A dinuclear copper(ii) complex derived from the chiral N6 ligand (2S,2'S)-N,N'-(ethane-1,2-diyl)bis(2-((1-methyl-1H-imidazol-4-ylmethyl)-amino)-3-(1-trityl-1H-imidazol-4-yl)propanamide) (EHI) was synthesized and studied as a catalyst in stereoselective oxidation reactions. The ligand contains two sets of tridentate binding units, each of them giving rise to a coordination set consisting of a pair of 5- and 6-membered chelate rings, connected by an ethanediamide linker. Stereoselectivity effects were studied in the oxidations of a series of chiral l/d biogenic catechols and the pair of l/d-tyrosine methyl esters, in this case as their phenolate salts. The oxidation of β-naphthol has also been studied as a model monooxygenase reaction. The catechol oxidation was investigated in a range of substrate concentrations at slightly acidic pH and exhibited a marked dependence on the concentration of the [Cu2EHI]4+ complex. This behavior has been interpreted in terms of an equilibrium between a monomeric and a dimeric form of the catalyst. Binding studies of l- and d-tyrosine were performed as a support for the interpretation of the stereoselectivity effects observed in the reactions. In general, [Cu2EHI]4+ exhibits a binding preference for the l- rather than the d-enantiomer of the substrates, but it appears that in the catecholase reaction the oxidation of the d-isomer occurs at a faster rate than for the l counterpart. The same type of enantio-discriminating behavior is observed in the oxidation of l-/d-tyrosine methyl esters. In this case the reaction produces a complex mixture of products; the main product consisting of a trimeric compound, likely formed by radical coupling reactions, has been isolated and characterized. The oxidation of β-naphthol yields an additional product of the expected quinone but labeling experiments with 18-O2show no oxygen incorporation into the product, confirming that the oxidation likely proceeds through a radical mechanism.

Pubblicazione: Anti-hypertensive property of a nickel-piperazine/NO donor in spontaneously hypertensive rats. Monti M, Ciccone V, Pacini A, Roggeri R, Monzani E, Casella L, Morbidelli L. Pharmacol Res. 2016 May;107:352-9. doi: 10.1016/j.phrs.2016.03.033.

Abtract:

The nickel-piperazine/NO donor compound, Ni(PipNONO)Cl, belonging to the family of compounds labelled as "metal-nonoates", due to its promising vasodilating activity, has been considered as a potential drug candidate in anti-hypertensive therapy. Drug efficacy has been evaluated in spontaneously hypertensive rats (SHR) in comparison with normotensive animals (C57BL/6 mice and WKY rats). In normotensive animals the metal-nonoate maintained blood pressure at basal level both following acute administration and after 30 days of treatment. In SHR, Ni(PipNONO)Cl reduced blood pressure in the dose range of 3-10mg/kg. When compared with a commercial NONOate, DETA/NO, used at the same doses, Ni(PipNONO)Cl was more active in reducing blood pressure in SHR than DETA/NO in the first two weeks, while the effect of the two molecules was similar in the third and fourth week. The degradation and control compound Ni(Pip)Cl2 had no effect on blood pressure and heart rate in same animal models. Remarkably, the blood pressure reduction induced by the new NO-donor Ni(PipNONO)Cl does not evoke changes in the heart rate and tolerance. Considering the mechanisms of vascular protection, 30 days of administration of Ni(PipNONO)Cl improved endothelial function in SHR by upregulating endothelial NO synthase (eNOS) through increased eNOS protein levels and downregulated Caveolin-1 (Cav-1), and by increasing superoxide dismutase 1 (SOD1) protein level in aortae. In cultured endothelial cells Ni(PipNONO)Cl restored the cell functions (cytoskeletal protein expression, migration and proliferation) altered by the inflammatory mediator interleukin-1β (IL-1β), impairing the endothelial to mesenchimal transition. In conclusion, Ni(PipNONO)Cl maintained unaltered blood pressure in normotensive mice and rats, and it exerted anti-hypertensive effect in SHR through the restoration of vascular endothelial protective functions.

Pubblicazione: Neuronal effects of a nickel-piperazine/NO donor complex in rodents. Sanna MD, Monti M, Casella L, Roggeri R, Galeotti N, Morbidelli L. Pharmacol Res. 2015 Sep;99:162-73. doi: 10.1016/j.phrs.2015.06.004.

Abtract:

In the brain, NO is a very important molecule in the regulation of cerebral and extra cerebral cranial blood flow and arterial diameters. It is also importantly involved in many neuronal functions and innumerable roles of NO in many brain related disorders including epilepsy, schizophrenia, drug addiction, anxiety, major depression, have been postulated. The present study aimed to explore the neuronal role exerted by the metal-nonoate compound Ni(PipNONO)Cl, a novel NO donor whose vascular protective effects have been recently demonstrated. Ni(PipNONO)Cl showed antidepressant-like properties in the tail suspension test and antiamnesic activity in the passive avoidance test in the absence of any hypernociceptive response to a mechanical stimulus. These effects were related to the NO-releasing properties of the compound within the central nervous system as demonstrated by the increase of iNOS levels in the brain, spinal cord and dura mater. The modulation of neuronal functions appeared after acute and repeated treatment, showing the lack of any tolerance to neuronal effects. At the dose used (10 mg/kg i.p.), Ni(PipNONO)Cl did not induce any visible sign of toxicity and experiments were performed in the absence of locomotor impairments. In addition to the NO-related neuronal activities of Ni(PipNONO)Cl, the decomposition control compound Ni(Pip)Cl2 showed anxiogenic-like and procognitive effects. The present findings showed neuronal modulatory activity of Ni(PipNONO)Cl through a NO-mediated mechanism. The activities of the decomposition compound Ni(Pip)Cl2 attributed to Ni(PipNONO)Cl the capability to modulate additional neuronal functions independently from NO releasing properties extending and improving the therapeutic perspectives of the NO donor.

Pubblicazione: Protective effects of novel metal-nonoates on the cellular components of the vascular system. Monti M, Solito R, Puccetti L, Pasotti L, Roggeri R, Monzani E, Casella L, Morbidelli L. J Pharmacol Exp Ther. 2014 Dec;351(3):500-9. doi: 10.1124/jpet.114.218404.

Abtract:

At cardiovascular level, nitric oxide (NO) controls smooth muscle functions, maintains vascular integrity and exerts anti-hypertensive effect. Metal-nonoates are a recently discovered class of NO donors, with NO release modulated through the complexation of the N-aminoethylpiperazine N-diazeniumdiolate ligand to metal ions and therefore representing a significant innovation with respect to the drugs traditionally used. In this study, we characterized the vascular protective effects of the most effective compound of this class, Ni(PipNONO)Cl, compared to the commercial NONOate derivate DETA/NO. Ni(PipNONO)Cl induced a concentration dependent relaxation of pre-contracted rat aortic rings. The ED50 was 0.67 μM, compared to 4.3 μM obtained with DETA/NO. When tested on cultured microvascular endothelial cells, Ni(PipNONO)Cl exerted a protective effect on the endothelium, promoting cell proliferation and survival in the range of pM. The administration of Ni(PipNONO)Cl to vascular smooth muscle cells reduced cell number, promoting their apoptosis at high concentration (10 μM). Inhibition of smooth muscle cell migration, a hallmark of atherosclerosis, was accompanied by cytoskeletal rearrangement and loss of lamellipodia. When added to isolated platelets, Ni(PipNONO)Cl significantly reduced ADP induced aggregation. Since atherosclerosis is accompanied by an inflammatory environment, cultured endothelial cells were exposed to interleukin-1 beta (IL-1β). In the presence of IL-1β, Ni(PipNONO)Cl inhibited cyclooxygenase.2 (COX-2) and inducible nitric oxide synthase (iNOS) upregulation, reduced endothelial permeability and the platelet and monocyte adhesion markers CD31 and CD40 at the plasma membrane. Overall, these data indicate that Ni(PipNONO)Cl exerts vascular protective effects relevant for vascular dysfunction and prevention of atherosclerosis and thrombosis

Pubblicazione: Nitric oxide releasing metal-diazeniumdiolate complexes strongly induce vasorelaxation and endothelial cell proliferation. Ziche M, Donnini S, Morbidelli L, Monzani E, Roncone R, Gabbini R, Casella L. ChemMedChem. 2008 Jul;3(7):1039-47. doi: 10.1002/cmdc.200700354. 

Abstract:

The preparation, characterization, and NO-releasing properties of metal complexes derived from N-aminoethylpiperazine-N-diazeniumdiolate (HPipNONO), [Cu(PipNONO)Cl] and [Ni(PipNONO)Cl], and the NiII complex derived from the Schiff base between HPipNONO and salicylaldehyde, [Ni(SalPipNONO)], are described. Compounds [Cu(PipNONO)Cl] and [Ni(SalPipNONO)] release NO at a much slower rate than HPipNONO in aqueous buffer in the pH range between 6.8 and 8.0. The kinetics of NO release by [Ni(SalPipNONO)] is complex, with an apparent stepwise release of NO molecules. Both [Cu(PipNONO)Cl] and [Ni(SalPipNONO)] are effective vasorelaxant agents of precontracted rabbit aorta rings, and are active in the nM concentration range. In addition, these complexes promote the proliferation of endothelial cells. Both vascular activities were inhibited by a specific inhibitor of guanylate cyclase, suggesting the involvement of the cGMP pathway. In all biological assays, the reference agent sodium nitroprusside was shown to be 10–1000-fold less potent than the two metal–NONOates.

 

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