Second generation ß-elemene nitric oxide derivatives with reasonable linkers: potential hybrids against malignant brain glioma.

Elemene is a second-line broad-spectrum anti-tumour drug that has been used in China for more than two decades. However, its main anti-tumour ingredient, ß-elemene, has disadvantages, including excessive lipophilicity and relatively weak anti-tumour efficacy. To improve the anti-tumour activity of ß-elemene, based on its minor molecular weight character, we introduced furoxan nitric oxide (NO) donors into the ß-elemene structure and designed six series of new generation ß-elemene NO donor hybrids. The synthesised compounds could effectively release NO in vitro, displayed significant anti-proliferative effects on U87MG, NCI-H520, and SW620 cell lines. In the orthotopic glioma model, compound Id significantly and continuously suppressed the growth of gliomas in nude mice, and the brain glioma of the treatment group was markedly inhibited (>90%). In short, the structural fusion design of NO donor and ß-elemene is a feasible strategy to improve the in vivo anti-tumour activity of ß-elemene.

Reaction mechanisms relevant to the formation and utilization of [Ru(edta)(NO)] complexes in aqueous media.

The advancement of Ru(edta) complexes (edta4- = ethylenediamineteraacetate) mediated reactions, including NO generation and its utilization, has not been systematically reviewed to date. This review aims to report the research progress that has been made in exploring the application of Ru(edta) complexes in trapping and generation of NO. Furthermore, utilization of the potential of Ru(edta) complexes to mimic NO synthase and nitrite reductase activity, including thermodynamics and kinetics of NO binding to Ru(edta) complexes, their NO scavenging (in vitro), and antitumor activity will be discussed. Also, the role of [Ru(edta)(NO)] in mediating electrochemical reduction of nitrite, S-nitrosylation of biological thiols, and cross-talk between NO and H2S, will be covered. Reports on the NO-related chemistry of Fe(edta) complexes showing similar behavior are contextualized in this review for comparison purposes. The research contributions compiled herein will provide in-depth mechanistic knowledge for understanding the diverse routes pertaining to the formation of the [Ru(edta)(NO)] species, and its role in effecting the aforementioned reactions of biochemical significance.

Enzyme-immobilized metal-organic framework nanosheets as tandem catalysts for the generation of nitric oxide.

An enzyme-immobilized metal-organic framework (MOF) nanosheet system was developed as a tandem catalyst, which converted glucose into gluconic acid and H2O2, and sequentially the latter could be used to catalyze the oxidation of l-arginine to generate nitric oxide in the presence of porphyrinic MOFs as artificial enzymes under physiological pH, showing great potential in cancer depleting glucose for starving-like/gas therapy.

Novel H2S-NO hybrid molecule (ZYZ-803) promoted synergistic effects against heart failure.

Therapeutic strategies that increase hydrogen sulfide (H2S) or nitric oxide (NO) are cytoprotective in various models of cardiovascular injury. However, the nature of interaction between H2S and NO in heart failure and the underlying mechanisms for the protective effects remain undefined. The present study tested the cardioprotective effect of ZYZ-803, a novel synthetic H2S-NO hybrid molecule that decomposed to release H2S and NO. ZYZ-803 dose dependently improved left ventricular remodeling and preserved left ventricular function in the setting of isoprenaline-induced heart failure. The cardioprotective effect of ZYZ-803 is significantly more potent than that of H2S and/or NO donor alone. ZYZ-803 stimulated the expression of cystathionine γ-lyase (CSE) for H2S generation and the activity of endothelial NO synthase (eNOS) for NO production. Blocking CSE and/or eNOS suppressed ZYZ-803-induced H2S and NO production and cardioprotection. ZYZ-803 increased vascular endothelial growth factor (VEGF) concentration and cyclic guanosine 5'-monophosphate (cGMP) level. Moreover, ZYZ-803 upregulated the endogenous antioxidants, glutathione peroxidase (GPx) and heme oxygenase 1 (HO-1). These findings indicate that H2S and NO cooperatively attenuates left ventricular remodeling and dysfunction during the development of heart failure through VEGF/cGMP pathway and ZYZ-803 provide expanding insight into strategies for treatment of heart failure.

A pH-Responsive Carrier System that Generates NO Bubbles to Trigger Drug Release and Reverse P-Glycoprotein-Mediated Multidrug Resistance.

Multidrug resistance (MDR) resulting from the overexpression of drug transporters such as P-glycoprotein (Pgp) increases the efflux of drugs and thereby limits the effectiveness of chemotherapy. To address this issue, this work develops an injectable hollow microsphere (HM) system that carries the anticancer agent irinotecan (CPT-11) and a NO-releasing donor (NONOate). Upon injection of this system into acidic tumor tissue, environmental protons infiltrate the shell of the HMs and react with their encapsulated NONOate to form NO bubbles that trigger localized drug release and serve as a Pgp-mediated MDR reversal agent. The site-specific drug release and the NO-reduced Pgp-mediated transport can cause the intracellular accumulation of the drug at a concentration that exceeds the cell-killing threshold, eventually inducing its antitumor activity. These results reveal that this pH-responsive HM carrier system provides a potentially effective method for treating cancers that develop MDR.

Synthesis, nitric oxide release, and α-glucosidase inhibition of nitric oxide donating apigenin and chrysin derivatives.

α-Glucosidase (AG) play crucial roles in the digestion of carbohydrates. Inhibitors of α-glucosidase (AGIs) are promising candidates for the development of anti-diabetic drugs. Here, five series of apigenin and chrysin nitric oxide (NO)-donating derivatives were synthesised and evaluated for their AG inhibitory activity and NO releasing capacity in vitro. Except for 9a-c, twelve compounds showed remarkable inhibitory activity against α-glucosidase, with potency being better than that of acarbose and 1-deoxynojirimycin. All organic nitrate derivatives released low concentrations of NO in the presence of l-cysteine. Structure activity relationship studies indicated that 5-OH, hydrophobic coupling chain, and carbonyl groups of the coupling chain could enhance the inhibitory activity. Apigenin and chrysin derivatives therefore represents a new class of promising compounds that can inhibit α-glucosidase activity and supply moderate NO for preventing the development of diabetic complications.

Enlarging the panoply of site-directed spin labeling electron paramagnetic resonance (SDSL-EPR): sensitive and selective spin-labeling of tyrosine using an isoindoline-based nitroxide.

Site-directed spin labeling (SDSL) combined with electron paramagnetic resonance (EPR) spectroscopy has emerged as a powerful approach to study structure and dynamics in proteins. One limitation of this approach is the fact that classical spin labels are functionalized to be grafted on natural or site-directed mutagenesis generated cysteine residues. Despite the widespread success of cysteine-based modification strategies, the technique becomes unsuitable when cysteine residues play a functional or structural role in the protein under study. To overcome this limitation, we propose an isoindoline-based nitroxide to selectively target tyrosine residues using a Mannich type reaction, the feasibility of which has been demonstrated in a previous study. This nitroxide has been synthesized and successfully grafted successively on p-cresol, a small tetrapeptide and a model protein: a small chloroplastic protein CP12 having functional cysteines and a single tyrosine. Studying the association of the labeled CP12 with its partner protein, we showed that the isoindoline-based nitroxide is a good reporter to reveal changes in its local environment contrary to the previous study where the label was poorly sensitive to probe structural changes. The successful targeting of tyrosine residues with the isoindoline-based nitroxide thus offers a highly promising approach, complementary to the classical cysteine-SDSL one, which significantly enlarges the field of applications of the technique for probing protein dynamics.

Copper(II) complexes with 2NO and 3N donor ligands: synthesis, structures and chemical nuclease and anticancer activities.

A series of water soluble copper(II) complexes of the types [Cu(L)Cl] 1-2, where LH is 2-(2-(1H-benzimidazol-2-yl)ethyliminomethyl)phenol (H(L1)), and 2-(2-(1H-benzimidazol-2-yl)-ethyliminomethyl)-4-methylphenol (H(L2)), and [Cu(L)Cl2] 3-6, where L is (2-pyridin-2-yl-ethyl)pyridin-2-ylmethyleneamine (L3), 2-(1H-benzimidazol-2-yl)ethylpyridin-2-yl-methyleneamine (L4), 2-(1H-benzimidazol-2-yl)ethyl(1H-imidazol-2-ylmethylene)amine (L5), and 2-(1H-benzimidazol-2-yl)ethyl-(4,4a-dihydroquinolin-2-ylmethylene)amine (L6), have been isolated and characterized by elemental analysis, electronic absorption, ESI-MS and EPR spectral techniques and the electrochemical method. The single crystal X-ray structures of [Cu(L1)Cl] 1 and [Cu(L2)Cl] 2 possess a distorted square-based coordination geometry while [Cu(L4)Cl2] 4 and [Cu(L6)Cl2] 6 possess a distorted trigonal bipyramidal coordination geometry. Both absorption spectral titration and an EthBr displacement assay reveal that all the complexes bind with calf thymus (CT) DNA through covalent mode of DNA interaction involving the replacement of an easily removable chloride ion with DNA nucleobases. All the complexes exhibit oxidative cleavage of supercoiled (SC) plasmid DNA in the presence of hydrogen peroxide as an activator. It is remarkable that at 50 µM concentration 5 and 6 completely degrade SC DNA into undetectable minor fragments and thus they act as efficient chemical nucleases. All the complexes are remarkable in displaying cytotoxicity against the HBL-100 human breast cancer cell line with potency more than that of the widely used drug cisplatin and hence they have the potential to act as promising anticancer drugs. Interestingly, they are non-toxic to normal cell lymphocytes isolated from human blood samples, revealing that they are selective in killing only the cancer cells.

Nitrite reduction mediated by heme models. Routes to NO and HNO?

The water-soluble ferriheme model Fe(III)(TPPS) mediates oxygen atom transfer from inorganic nitrite to a water-soluble phosphine (tppts), dimethyl sulfide, and the biological thiols cysteine (CysSH) and glutathione (GSH). The products with the latter reductant are the respective sulfenic acids CysS(O)H and GS(O)H, although these reactive intermediates are rapidly trapped by reaction with excess thiol. The nitrosyl complex Fe(II)(TPPS)(NO) is the dominant iron species while excess substrate is present. However, in slightly acidic media (pH ≈ 6), the system does not terminate at this very stable ferrous nitrosyl. Instead, it displays a matrix of redox transformations linking spontaneous regeneration of Fe(III)(TPPS) to the formation of both N2O and NO. Electrochemical sensor and trapping experiments demonstrate that HNO (nitroxyl) is formed, at least when tppts is the reductant. HNO is the likely predecessor of the N2O. A key pathway to NO formation is nitrite reduction by Fe(II)(TPPS), and the kinetics of this iron-mediated transformation are described. Given that inorganic nitrite has protective roles during ischemia/reperfusion (I/R) injury to organs, attributed in part to NO formation, and that HNO may also reduce net damage from I/R, the present studies are relevant to potential mechanisms of such nitrite protection.

Penile erectile activity of dinitrosyl iron complexes with thiol-containing ligands.

It has been established that intracavernous injections of water-soluble dinitrosyl iron complexes (DNIC) with glutathione or cysteine (0.4-6.0µmoles/kg) to male rats induce short-term (2-3 min) penile erection along with a short-term drop of arterial pressure and appearance of protein-bound DNIC in cavernous tissue and circulating blood. The duration of erection and the hypotensive activity of DNIC increase dramatically after simultaneous intracavernous injection of DNIC and the phosphodiesterase-5 inhibitor papaverine. Surgical denervation of cavernous bodies does not influence the erectile activity of DNIC. No penile erection takes place after intravenous (instead of intracavernous) injection of the same dose of DNIC; in this case, protein-bound DNIC are detected only in the blood. These findings suggest that water-soluble DNIC with thiol-containing ligands (cysteine or glutathione) can be used as a basis in the design of a novel class of drugs for treating erectile dysfunctions.

A new method for sustained generation of ultra-pure nitric oxide-containing gas mixtures via controlled UVA-photolysis of nitrite solutions.

Exogenous gaseous nitric oxide (gNO) is an FDA approved drug for treatment of a variety of human pathologies like Persistent Pulmonary Hypertension in neonates and premature babies, skin lesions and fungal dermatophyte infections. Substantial disadvantages of current gNO-based therapies are the high therapy costs, high storage costs of the gas cylinders, and the rapid contamination of compressed NO gases with various decomposition products. Here we describe a new, very simple, and inexpensive photolytic generator of uncontaminated NO-containing gas mixtures at therapeutic concentrations. The new method bases on UVA-induced and redox-assisted decomposition of nitrite ions in aqueous solutions. NO formation via UVA-induced photolysis of nitrite is accompanied by an OH radical-dependent production of NO(2) that beside its toxic character additionally strongly reduces the NO yield by consuming NO in its reaction to N(2)O(3). During the UVA-induced photodecomposition process both, inhibition of NO(2) formation or NO(2) depletion by antioxidants hinders the NO-consuming reaction with NO(2) and ensured a maximal purity and maximal yield of NO-containing gas mixtures. Therefore, NO-containing gas mixtures generated by the described method are suitable for medical applications like inhalation or gassing of chronic non-healing wounds. Control of temperature, UVA intensity and composition of the reaction mixture allows facile control over the final NO level in the carrier gas over a wide concentration range. We demonstrate the sustained and stable release of NO over a wide dynamic range (10-5000 ppm NO) for many hours. The method avoids contamination-prone long time storage of NO gas. As such, it appears particularly relevant for applications involving the additional presence of oxygen (e.g. inhalation).

Formation of the distinct redox-interrelated forms of nitric oxide from reaction of dinitrosyl iron complexes (DNICs) and substitution ligands.

Release of the distinct NO redox-interrelated forms (NO(+), *NO, and HNO/NO(-)), derived from reaction of the dinitrosyl iron complex (DNIC) [(NO)(2)Fe(C(12)H(8)N)(2)](-) (1) (C(12)H(8)N=carbazolate) and the substitution ligands (S(2)CNMe(2))(2), [SC(6)H(4)-o-NHC(O)(C(5)H(4)N)](2) ((PyPepS)(2)), and P(C(6)H(3)-3-SiMe(3)-2-SH)(3) ([P(SH)(3)]), respectively, was demonstrated. In contrast to the reaction of (PyPepS)(2) and DNIC 1 in a 1:1 stoichiometry that induces the release of an NO radical and the formation of complex [PPN][Fe(PyPepS)(2)] (4), the incoming substitution ligand (S(2)CNMe(2))(2) triggered the transformation of DNIC 1 into complex [(NO)Fe(S(2)CNMe(2))(2)] (2) along with N-nitrosocarbazole (3). The subsequent nitrosation of N-acetylpenicillamine (NAP) by N-nitrosocarbazole (3) to produce S-nitroso-N-acetylpenicillamine (SNAP) may signify the possible formation pathway of S-nitrosothiols from DNICs by means of transnitrosation of N-nitrosamines. Protonation of DNIC 1 by [P(SH)(3)] triggers the release of HNO and the generation of complex [PPN][Fe(NO)P(C(6)H(3)-3-SiMe(3)-2-S)(3)] (5). In a similar fashion, the nucleophilic attack of the chelating ligand P(C(6)H(3)-3-SiMe(3)-2-SNa)(3) ([P(SNa)(3)]) on DNIC 1 resulted in the direct release of [NO](-) captured by [((15)NO)Fe(SPh)(3)](-), thus leading to [((15)NO)((14)NO)Fe(SPh)(2)](-). These results illustrate one aspect of how the incoming substitution ligands ((S(2)CNMe(2))(2) vs. (PyPepS)(2) vs. [P(SH)(3)]/[P(SNa)(3)]) in cooperation with the carbazolate-coordinated ligands of DNIC 1 function to control the release of NO(+), *NO, or [NO](-) from DNIC 1 upon reaction of complex 1 and the substitution ligands. Also, these results signify that DNICs may act as an intermediary of NO in the redox signaling processes by providing the distinct redox-interrelated forms of NO to interact with different NO-responsive targets in biological systems.

Pterin-centered radical as a mechanistic probe of the second step of nitric oxide synthase.

The enzyme nitric oxide synthase is both medically relevant and of particular interest from a basic sciences perspective due to the complex nature of the chemical mechanism used to generate NO. The enzyme utilizes multiple redox-active cofactors and substrates to catalyze the five-electron oxidation of substrate l-arginine to citrulline and nitric oxide. Two flavins, a cysteine-coordinated heme cofactor and, uniquely, a tetrahydrobiopterin cofactor, are used to deliver electrons from the cosubstrate NADPH to molecular oxygen, analogous to other P450s. The unprecedented involvement of the pterin cofactor as a single electron donor is unique among P450s and pterin utilizing proteins alike and adds to the complexity of this enzyme. In this report, the peroxide shunt with both Mn- and Fe-containing heme domain constructs of iNOS(heme) was used to characterize the formation of HNO as the initial inorganic product produced when oxygen activation occurs without pterin radical formation. To recover NO formation, preturnover of the iron-containing enzyme with l-arginine was used to generate the pterin-centered radical, followed by peroxide shunt chemistry. Comparison of NO produced by this reaction with reactions that do not undergo preturnover, do not have peroxide added, or are performed with a pterin unable to generate a radical shows NO production to be dependent on both a pterin-centered radical and activated oxygen. Finally, the chemical HNO donor, Angeli's salt, was used to form the ferrous nitrosyl in the presence of the pterin radical intermediate. Under these conditions, the rate of pterin radical decay was increased as monitored by EPR spectroscopy. In comparison to pterin that aerobically decays, the Angeli's salt treated sample is also significantly protected from oxidation, suggesting ferrous-nitrosyl-mediated reduction of the radical. Taken together, these results support a dual redox cycling role for the pterin cofactor during NOS turnover of NHA with particular importance for the proper release of NO from a proposed ferrous nitrosyl intermediate.

Preventive effect of curcumin and quercetin against nitric oxide mediated modification of goat lung cystatin.

Cysteine proteinase inhibitors are of prime physiologic importance inside the cells, controlling the activities of lysosomal cysteine proteases. The present work aimed to realize the effects of nitric oxide on the structure and function of goat lung cystatin (GLC) and to evaluate antinitrostative efficacy of curcumin and quercetin. Nitric oxide induced structural modifications were followed by fluorescence spectroscopy and PAGE and functional inactivation by monitoring the inhibition of caseinolytic activity of papain. Ten millimolar sodium nitroprusside (SNP) caused time dependent inactivation of GLC-I with complete functional loss precipitating at 180 min. Curcumin (50 microM) and quercetin (250 microM) opposed such loss in papain inhibitory activity of GLC-I. Loss in tertiary structure of GLC-I (fluorescence quenching and 15 nm red shift) was observed on SNP treatment. Inhibition of functional and structural SNP mediated damage of GLC-I by curcumin (50 microM) and quercetin (250 microM) reaffirms their NO scavenging potency.

Estudo da expressão imunoistoquímica e do valor prognóstico de sintases do óxido nítrico (NOS), metaloproteinases da matriz extracelular (MMP), fator de crescimento endotelial vascular (VEGF), caderina e, densidade de microvasos (DMV) e da densidade de vasos linfáticos (DVL) em pacientes portadores de carcinoma de células renais / Study of immunohistochemical expression and value prognosis of nitric oxide synthases (NOS), metalloproteinases of extracellular matrix (MMP), vascular endothelial growth factor (VEGF), cadherin e, microvessel density (DMV) and the density of lymphatic vessels (DVL) in patients with carcinoma of renal cells

Introdução: O carcinoma de células renais (CCR) é neoplasia altamente letal, com evolução incerta. Novos fatores prognósticos biomoleculares em CCR são necessários. ... Dados epidemiológicos clínicos e patológicos foram coletados. Empregaram-se classificações de performance status da Eastern Cooperative Oncologic Group (ECOG), Karnofsky Performance Status (KPS) e a classificação da American Society of Anesthesiology (ASA) ... A partir da análise univariada, criou-se um Modelo Multivariado Hierárquico (MMH), que submetido à análise multivariada, permitiu a elaboração de um escore com as variáveis prognósticas mais significativas para SG e SLD. Resultados: Na análise univariada, dentre os marcadores biomoleculares, apenas a NOS-3 (p=0,047) e DMV (p=0, 052) tiveram impacto na SG. .... Na análise univariada de SLD para os 94 pacientes sem metástases, nenhum marcador biomolecular teve impacto significativo (p>0,05). Na análise multivariada para SLD, apenas o estádio Clínico foi fator independente. O estádio III (ajustado pelo estádio I) teve HR de 9,5 vezes para recidiva. Conclusão: Fatores clínicos usuais permaneceram como os fatores preditivos mais significativos em CCR e permitiram a elaboração de um escore prognóstico, no qual pacientes com mais de 4 pontos tiveram chance de óbito de mais de 50%. Este escore deve ser testado em outras casuísticas. Futuros estudos sobre as correlações da NOS-3 e seu papel prognóstico no CCR devem ser realizados.

Introduction: Renal cell carcinoma (RCC) is a tumor with high mortality rate and uncertain evolution. Therefore, new molecular factors in RCC are necessary. This study aims: to evaluate the expression of Nitric Oxide Sintases types 1, 2 and 3 (NOS-1, NO-2, NOS-3), matrix metalloproteases types 2 and 9 (MMP-2 and MMP-9), E-Cadherin and vascular endothelial growth factor (VEGF) through imunohistochemical analysis; to evaluate microvessel density (MVD) and lymphatic vessel density (LVD); to verify the association among biomarkers expression and epidemiological, clinic and pathological variables; to verify the impact of the variables as prognostic factors in 5 years overall survival (OS) and disease free survival (DFS). Material and Methods: One-hundred and ten patients with RCC were included. Clinical, epidemiological and pathological data were collected from medical charts. Performance status classifications used were: Eastern Cooperative Oncologic Group Classification (ECOG) and Karnofsky Performance Status (KPS) and the American Society of Anesthesiology Classification (ASA). The Tissue Microarray (TMA) was used and a digital microscopy program (ACIS III) was empregated. To predict recurrence, progression our death, the variables selected by univariate analysis were included in a Hierarchic Multivariate Model (HMM), to estimate the odds of deaths or disease progression or recurrence. Results: In the univariate analysis, NOS-3 (p=0.047) and MVD (p=0.052) had impact in OS. Patients with low expression of NOS-3 had an OS of 79% versus 58.1% for patients with high expression of NOS-3. The MVD showed direct correlation with OS rates: patients with high MVD had higher OS (79.9%) than the patients with low MVD (58%). E-cadherin, the VEGF, the MMP-2, MMP-9 and DVL expression were not correlated with OS and DFS. NOS expression (NOS- 1, NOS - 2 and NOS - 3) were directly correlated with tumor size: patients with low NOS expression had tumors 2.0 to 3.0cm smaller than patients with high NOS expression. High expression of NOS-3 was correlated with lymph node metastasis (31% versus 9.7%, p=0.029), with renal pelvis and ureter invasion (16% versus 3.3%, p= 0.0041) and with a higher rate of radical nephrectomies (88% versus 63.3%, p=0.003). The high expression of the MMP-2 and the MMP-9 were correlated with high grade tumors (p=0.046 and p=0.009 respectively) and with histological type not clear cell (p=0.029 and p=0.009, respectively). In the OS multivariate analysis, the significant prognostic factors were: TNM clinical staging (HR=4.5), grade (HR=2.9), KPS (HR=2.5), the occurrence of post-nephrectomy progression (HR = 5.3) and/or recurrence (HR= 6.5), all of them adjusted by the age (HR=1.1). The HMM score ranged of 0 the 7 points. There were no deaths among patients with 0 point and all patients with 7 points have died. According to the HMM score, the probability to be alive for 0, 1-2, 3-4, 5-7 score levels was respectively 100%, 83.5%, 53,5 and 13.5%. In the univariate DFS analysis for the 94 patients without metastases (16 of the 110 patients had metastasis at diagnosis), no molecular marker had significant impact. In the multivariate analysis for DFS, only the TNM clinical staging was an independent prognostic factor. Clinical staging III had HR of 9.5 times for recurrence. Conclusions: Usual clinical factors remained as most important prognostic factors in RCC and had allowed the elaboration of one score, in which patients with more than 4 points has a death probability rate higher than 50%. This MMH score must be validated for other groups. Future studies regarding the correlations and the prognostic role of NOS-3 in RCC must be conducted.

Escenciales en biomedicina (biología, patobiología y bioclínica) humana de las NOSS (Óxido Nítrico-Sintetasas): [revisión] / Essentials in human biomedicine (biology, patobiology and bioclinic)of the nitric oxide synthetases (NOS): [review]

El Óxido Nítrico (NO) es un radical libre gaseoso que juega roles prominentes en señalamiento celular, expresión y regulación génica, energética celular, proliferación celular y citostasis, e inmunidad celular y tolerancia, incluyendo funciones inflamatorias. Aunque NO sirve a roles beneficiosos como citotrófico, vasodilatador, antiangiogénico, anti-trombótico, anti-inflamatorio, defensa inmune del huésped, antiproliferativo y antioxidante, su excesiva producción puede ser citotóxica, vasoconstrictora, pro-angiogénica, protrombótica, pro-inflamatoria, proproliferativa y oxidante, a causa de la endógena producción de intermediarios reactivos del nitrógeno y/o el oxígeno. Esta revisión explora el conocimiento colectivo del rol de las NO-Sintetasas (NOSs) en biología, patobiología, bioclínica humana y nuevas oportunidades en prevención y tratamiento...

The Nitric Oxide (NO) is a gaseosus free radical that plays prominent roles in cell signaling, gene expression and regulation, cellular energetics, cell proliferation and cytostasis, and cell immunity and tolerence including inflammatory functions. Althoug NO serves benificial rolesas cytotrophic, vasodilator, anti-angiogenic, antithrombotic, anti-inflammatory, host defense, antiproliferativeand antioxidant, excessive production can be cytotoxic, vasoconstrictor, pro-angiogenic, prothrombotic, proinflammatory, pro-proliferative and oxidant, because endogenous production of reactive nitrogen and/o oxygen intermediates. The review explores the collective knowledge of the role of NO-Synthetases (NOSs) in human biology, pathobiology, bioclinic and new opportunities in prevention and treatment.

Chemical insights in the concept of hybrid drugs: the antitumor effect of nitric oxide-donating aspirin involves a quinone methide but not nitric oxide nor aspirin.

Hybrid drug 1 (NO-ASA) continues to attract intense research from chemists and biologists alike. It consists of ASA and a -ONO2 group connected through a spacer and is in preclinical development as an antitumor drug. We report that, contrary to current beliefs, neither ASA nor NO contributes to this antitumor effect. Rather, an unsubstituted QM was identified as the sole cytotoxic agent. QM forms from 1 after carboxylic ester hydrolysis and, in accordance with the HSAB theory, selectively reacts with cellular GSH, which in turn triggers cell death. Remarkably, a derivative lacking ASA and the -ONO2 group is 10 times more effective than 1. Thus, our data provide a conclusive molecular mechanism for the antitumor activity of 1. Equally importantly, we show for the first time that a "presumed invisible" linker in a hybrid drug is not so invisible after all and is in fact solely responsible for the biological effect.

PABA/NO as an anticancer lead: analogue synthesis, structure revision, solution chemistry, reactivity toward glutathione, and in vitro activity.

PABA/NO is a diazeniumdiolate of structure Me(2)NN(O)=NOAr (where Ar is a 5-substituted-2,4-dinitrophenyl ring whose 5-substituent is N-methyl-p-aminobenzoic acid). It has shown activity against human ovarian cancer xenografts in mice rivaling that of cisplatin, but it is poorly soluble and relatively unstable in water. Here we report structure-based optimization efforts resulting in three analogues with improved solubility and stability in aqueous solution. We sought to explain PABA/NO's physicochemical uniqueness among these four compounds, whose aminobenzoic acid precursors differ structurally only in the presence or absence of the N-methyl group and/or the position of the carboxyl moiety (meta or para). Studies revealed that PABA/NO's N-methyl-p-aminobenzoic acid substituent is bound to the dinitrobenzene ring via its carboxyl oxygen while the other three are linked through the aniline nitrogen. This constitutes a revision of the previously published PABA/NO structure. All four analogues reacted with GSH to produce bioactive nitric oxide (NO), but PABA/NO was the most reactive. Consistent with PABA/NO's potent suppression of A2780 human ovarian cancer xenograft growth in mice, it was the most potent of the four in the OVCAR-3 cell line.

Photoinduced nitric oxide release from nitrobenzene derivatives.

A new type of photoinduced nitric oxide (NO) donors was designed from nitrobenzene derivatives. Visible-light irradiation of 2,6-dimethylnitrobenzenes bearing extended pi-electron systems at the 4-position revealed efficient NO release using ESR analysis and the Griess assay. Computational study and ultraviolet spectrum analysis suggested that the NO-releasing activity was closely related to the conformation of the nitro group, the absorption intensity, and the length of the conjugated pi-electron system. Employing the photodependent cytotoxicity of compound 14 against HCT116 human colon cancer cells, it was demonstrated that 4-substituted-2,6-dimethylnitrobenzene analogues are useful NO donors for the time- and site-controlled NO treatment.