The influence of thioether-substituted ligands in dicopper(II) complexes: Enhancing oxidation and biological activities.

This paper describes the synthesis, structural analysis, as well as the magnetic and spectroscopic characterizations of three new dicopper(II) complexes with dinucleating phenol-based ligands containing different thioether donor substituents: aromatic (1), aliphatic (2) or thiophene (3). Temperature-dependent magnetometry reveals the presence of antiferromagnetic coupling for 1 and 3 (J = -2.27 cm-1 and -5.01 cm-1, respectively, H = -2JS1S2) and ferromagnetic coupling for 2 (J = 5.72 cm-1). Broken symmetry DFT calculations attribute this behavior to a major contribution from the dz2 orbitals for 1 and 3, and from the dx2-y2 orbitals for 2, along with the p orbitals of the oxygens. The bioinspired catalytic activities of these complexes related to catechol oxidase were studied using 3,5-di-tert-butylcatechol as substrate. The order of catalytic rates for the substrate oxidation follows the trend 1 > 2 > 3 with kcat of (90.79 ± 2.90) × 10-3 for 1, (64.21 ± 0.99) × 10-3 for 2 and (14.20 ± 0.32) × 10-3 s-1 for 3. The complexes also cleave DNA through an oxidative mechanism with minor-groove preference, as indicated by experimental and molecular docking assays. Antimicrobial potential of these highly active complexes has shown that 3 inhibits both Staphylococcus aureus bacterium and Epidermophyton floccosum fungus. Notably, the complexes were found to be nontoxic to normal cells but exhibited cytotoxicity against epidermoid carcinoma cells, surpassing the activity of the metallodrug cisplatin. This research shows the multifaceted properties of these complexes, making them promising candidates for various applications in catalysis, nucleic acids research, and antimicrobial activities.

Enhancing the biological properties of zinc complexes with bis(indolyl)methane groups: Synthesis, characterization, DNA interaction, and biocide activity.

The unprecedented mononucleated ligand (6,6-di(1H-indol-3-yl)-N,N-bis(pyridin-2-ylmethyl)hexan-1-amine (LC5) with an N3-donor set and its complexes [Zn(LC5)Cl2] • 2CH3OH (1) and [Zn(LC5)2](ClO4)2 (2), were successfully prepared. All compounds were fully characterized by a suite of physicochemical methods. Fluid 1H and 13C NMR spectroscopy, as well as DFT and TD-DFT calculations, were carried out to propose a viable structural arrangement for both complexes. The interaction between these compounds and DNA was monitored in the UV region where binding constants (Kb) were estimated (2 > 1 > LC5). These data were corroborated by DNA cleavage assays using groove binders, circular dichroism, and docking studies. Both complexes confirmed their biocide activity against selected microorganisms: Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria, the filamentous fungi A. fumigatus and S. cerevisiae. Finally, the cytotoxic activities of 1 and 2 were tested against the erythroleukemia K562 cell line. For all biological studies, it was probed that the presence of the indole moieties and the zinc atoms in the chemical composition of the complexes studied could increase the magnitude of the activity following the order: 2 > 1 > LC5, where a linear relationship between the biological activity upon K562 cells (IC50) and DNA binding studies (Kb) was found.

Inhibiting IRE-1 RNase signaling decreases HIV-1 Tat-induced inflammatory M1 state in microglial cells.

HIV-1 transactivator (Tat) protein plays a critical role in neurological disorders resulting from viral infection, commonly known as HIV-1-associated neurocognitive disorders (HAND). Previous studies have shown that circulant Tat induces M1 microglial activation, one of the hallmark features of HAND, and this is coupled with ER stress and subsequent Unfolded Protein Response (UPR) triggering. Here, we demonstrate that bystander stimuli of Tat in microglial cells result in the simultaneous overexpression of IRE1-related markers and production of M1-typed proinflammatory mediators. We also show that blocking IRE1/XBP-1 signaling using 4µ8C diminishes such inflammatory response. These findings reinforce a role for the IRE1/XBP-1 pathway in HIV-1 Tat neuropathology and suggest that targeting IRE1 RNase activity using 4µ8C or analogue compounds may provide a therapeutic intervention to mitigate against neuroinflammation in HAND.

Pharmacological inhibition of UPR sensor PERK attenuates HIV Tat-induced inflammatory M1 phenotype in microglial cells.

HIV-1-associated neurocognitive disorders (HAND) are a major concern in HIV-infected individuals despite the currently available antiretroviral therapy regime. Impaired M1 pro-inflammatory microglial activation is considered one of the hallmark features of HAND neuropathogenesis, and it has been suggested that circulant HIV-1 transactivator protein (Tat) can play a critical role in this process. At the same time, endoplasmatic reticulum (ER) stress has also been implicated in neurodegenerative conditions resulting from the accumulation of misfolded proteins and subsequent unfolded protein response (UPR) deflagration. Here, we demonstrate that pharmacological inhibition of UPR-related protein kinase R-like endoplasmic reticulum kinase (PERK) can attenuate HIV-1 Tat-induced M1 inflammatory state in microglia in vitro. Our initial experiments demonstrate that the bystander stimulus of recombinant Tat on BV-2 microglial cells result in the coupled overexpression of central UPR markers and pro-inflammatory mediators such as iNOS, surface CD16/32 and secreted tumour necrosis factor-α (TNF-α), IL-6, monocyte chemoattractant protein (MCP)-1 and NO. We show that blocking PERK-eIF2-α-ATF4 signalling using the PERK inhibitor GSK2606414 leads to reduced inflammatory response in M1-like BV-2 cells activated by recombinant Tat. Taken together, these findings suggest that PERK targeting may provide a therapeutic intervention to mitigate against lasting neuroinflammation and neuronal loss in of HAND.

Crystal structure of the Cys-NO modified YopH tyrosine phosphatase.

Protein tyrosine phosphatases (PTPs) are key virulence factors in pathogenic bacteria, consequently, they have become important targets for new approaches against these pathogens, especially in the fight against antibiotic resistance. Among these targets of interest YopH (Yersinia outer protein H) from virulent species of Yersinia is an example. PTPs can be reversibly inhibited by nitric oxide (NO) since the oxidative modification of cysteine residues may influence the protein structure and catalytic activity. We therefore investigated the effects of NO on the structure and enzymatic activity of Yersinia enterocolitica YopH in vitro. Through phosphatase activity assays, we observe that in the presence of NO YopH activity was inhibited by 50%, and that this oxidative modification is partially reversible in the presence of DTT. Furthermore, YopH S-nitrosylation was clearly confirmed by a biotin switch assay, high resolution mass spectrometry (MS) and X-ray crystallography approaches. The crystal structure confirmed the S-nitrosylation of the catalytic cysteine residue, Cys403, while the MS data provide evidence that Cys221 and Cys234 might also be modified by NO. Interestingly, circular dichroism spectroscopy shows that the S-nitrosylation affects secondary structure of wild type YopH, though to a lesser extent on the catalytic cysteine to serine YopH mutant. The data obtained demonstrate that S-nitrosylation inhibits the catalytic activity of YopH, with effects beyond the catalytic cysteine. These findings are helpful for designing effective YopH inhibitors and potential therapeutic strategies to fight this pathogen or others that use similar mechanisms to interfere in the signal transduction pathways of their hosts.

A heterotrinuclear bioinspired coordination complex capable of binding to DNA and emulation of nuclease activity.

The investigation of compounds capable of strongly and selectively interacting with DNA comprises a field of research in constant development. In this work, we demonstrate that a trinuclear coordination complex based on a dinuclear Fe(III)Zn(II) core designed for biomimicry of the hydrolytic enzyme kidney bean purple acid phosphatase, containing an additional pendant arm coordinating a Pd(II) ion, has the ability to interact with DNA and to promote its hydrolytic cleavage. These results were found through analysis of plasmid DNA interaction and cleavage by the trinuclear complex 1 and its derivatives 2 and 3, in addition to the analysis of alteration in the DNA structure in the presence of the complexes through circular dichroism and DNA footprinting techniques. The suggested covalent interaction of the palladium-containing complex with DNA was analysed using an electrophoretic mobility assay, circular dichroism, high resolution gel separation techniques and kinetic analysis. This is a new and promising metal complex targeted to nucleic acids and acting in two separate ways: strong DNA interaction and hydrolytic cleavage.

Dinuclear copper(II) complexes with derivative triazine ligands as biomimetic models for catechol oxidases and nucleases.

The research reported herein focuses on the synthesis of two new Cu(II) complexes {[Cu2(2-X-4,6-bis(di-2-picolylamino)-1,3,5-triazine], with X = butane-1,4-diamine (2) or N-methylpyrenylbutane-1,4-diamine (3)}, the latter with a pyrene group as a possible DNA intercalating agent. The structure of complex (3) was determined by X-ray crystallography and shows the dinuclear {CuII(µ-OCH3)2CuII} unit in which the CuII···CuII distance of 3.040 Å is similar to that of 2.97 Å previously found for 1, which contains a {CuII(µ-OH)2CuII} structural unit. Complexes (2) and (3) were also characterized in spectroscopic and electrochemical studies, and catecholase-like activity were performed for both complexes. The kinetic parameters obtained for the oxidation of the model substrate 3,5-di-tert-butylcatechol revealed that the insertion of the spacer butane-1,4-diamine and the pyrene group strongly contributes to increasing the catalytic efficiency of these systems. In fact, Kass becomes significantly higher, indicating that these groups influence the interaction between the complex and the substrate. These complexes also show DNA cleavage under mild conditions with moderate reaction times. The rate of cleavage (kcat) indicated that the presence of butane-1,4-diamine and pyrene increased the activity of both complexes. The reaction mechanism seems to have oxidative and hydrolytic features and the effect of DNA groove binding compounds and circular dichroism indicate that all complexes interact with plasmid DNA through the minor groove. High-resolution DNA cleavage assays provide information on the interaction mechanism and for complex (2) a specificity for the unpaired hairpin region containing thymine bases was observed, in contrast to (3).

Evaluation of DNA-binding and DNA-photocleavage ability of tetra-cationic porphyrins containing peripheral [Ru(bpy)2Cl]+ complexes: Insights for photodynamic therapy agents.

The present work reports the spectroscopic and theoretical evaluation of the interaction between calf-thymus DNA (CT-DNA) and free-base meso-tetra-(ruthenated) porphyrin (H2RuTPyP) or its corresponding Zn(II) complex (ZnRuTPyP). Spectroscopic measurements (UV-vis, circular dichroism and steady-state fluorescence emission) combined with theoretical molecular docking calculations suggest that Ru(II)-porphyrins interact with the DNA backbone by external mode via electrostatic forces. In addition, gel electrophoresis analysis demonstrate that these porphyrins promote efficient plasmidial DNA photocleavage upon white-light irradiation conditions, indicating H2RuTPyP and ZnRuTPyP as potential candidates for photodynamic therapy.

A chalcone derivative binds a putative allosteric site of YopH: Inhibition of a virulence factor of Yersinia.

Identification of allosteric inhibitors of PTPs has attracted great interest as a new strategy to overcome the challenge of discover potent and selective molecules for therapeutic intervention. YopH is a virulence factor of the genus Yersinia, validated as an antimicrobial target. The finding of a second substrate binding site in YopH has revealed a putative allosteric site that could be further exploited. Novel chalcone compounds that inhibit PTPs activity were designed and synthesized. Compound 3j was the most potent inhibitor, interestingly, with different mechanisms of inhibition for the panel of enzymes evaluated. Further, our results showed that compound 3j is an irreversible non-competitive inhibitor of YopH that binds to a site different than the catalytic site, but close to the well-known second binding site of YopH.

The antidiabetic drug lobeglitazone has the potential to inhibit PTP1B activity.

Protein tyrosine phosphatase 1B (PTP1B) is considered a potential therapeutic target for the treatment of type 2 diabetes mellitus (T2DM), since this enzyme plays a significant role to down-regulate insulin and leptin signalling and its over expression has been implicated in the development of insulin resistance, T2DM and obesity. Some thiazolidinediones (TZD) derivatives have been reported as promising PTP1B inhibitors with anti hyperglycemic effects. Recently, lobeglitazone, a new TZD, was described as an antidiabetic drug that targets the PPAR-γ (peroxisome γ proliferator-activated receptor) pathway, but no information on its effects on PTP1B have been reported to date. We investigated the effects of lobeglitazone on PTP1B activity in vitro. Surprisingly, lobeglitazone led to moderate inhibition on PTP1B (IC50 42.8 ± 3.8 µM) activity and to a non-competitive reversible mechanism of action. As lobeglitazone inhibits PTP1B activity in vitro, we speculate that it could also target PTP1B signalling pathway in vivo and thus contribute to potentiate its antidiabetic effects.

Targeting an Artificial Metal Nuclease to DNA by a Simple Chemical Modification and Its Drastic Effect on Catalysis.

A novel metal complex was synthesized containing a purine derived ligand in order to increase its binding to DNA. We observed a huge increase in nuclease activity and, quite interestingly, an improvement on DNA sequence selectivity. A potential site of specific cleavage in the presence of a reductant in the reaction medium is suggested. We were able to synthesize a novel metal nuclease with improved activity on DNA, and with sequence specificity when exposed to a coreactant, this opens up new possibilities to create site specific and redox status modulated artificial nucleases.

A Type IIa crustin from the pink shrimp Farfantepenaeus paulensis (crusFpau) is constitutively synthesized and stored by specific granule-containing hemocyte subpopulations.

Crustins are cysteine-rich antimicrobial peptides (AMPs) widely distributed across crustaceans. From the four described crustin Types (I to IV), crustins from the subtype IIa are the most abundant and diverse members found in penaeid shrimp. Despite the critical role of Type IIa crustins in shrimp antimicrobial defenses, there is still limited information about their synthesis and antimicrobial properties. Here, we report the subcellular localization and the antibacterial spectrum of crusFpau, a Type IIa crustin from the pink shrimp Farfantepenaeus paulensis. The recombinantly expressed crusFpau showed antimicrobial activity against both Gram-positive and Gram-negative bacteria at low concentrations. Results from immunofluorescence using anti-rcrusFpau antiserum revealed that crusFpau is synthetized and stored by both granular and semigranular hemocytes, but not by hyaline cells. Interestingly, not all granular and semigranular hemocytes stained for crusFpau, revealing that this crustin is produced by specific granule-containing hemocyte subpopulations. Finally, we showed that the granule-stored peptides are not constitutively secreted into the plasma of healthy animals.

Guanidine- and purine-functionalized ligands of FeIIIZnII complexes: effects on the hydrolysis of DNA.

In this paper, the catalytic effects of aminoguanidine and aminopurine groups in the second sphere of a FeIIIZnII complex that mimics the active site of the metallohydrolase purple acid phosphatase (PAP) are investigated, with a particular view on DNA as substrate. The ligand 3-(((3-((bis(2-(pyridin-2-yl)ethyl)amino)methyl)-2-hydroxy-5-methylbenzyl)(pyridin-2-ylmethyl)amino)meth-yl)-2 hydroxy-5-methylbenzaldehyde-(H2L1bpea) was synthesized and its complex [(OH)FeIII(µ-OH)ZnII(H2O)(L1bpea)](ClO4) was used as a base for comparison with similar complexes previously published in the literature. Subsequent modifications were conducted in the aldehyde group, where aminoguanidine (amig) and aminopurine (apur) were used as side chain derivatives. The complexes [(OH)FeIII(µ-OH)ZnII(H2O)(L1bpea)](ClO4) (1), [(OH)FeIII(µ-OH)ZnII(H2O)(L1bpea-amig)](ClO4) (2) and [(OH)FeIII(µ-OH)ZnII(H2O)(L1bpea-apur)](ClO4) (3) were characterized by spectroscopic methods (infrared, UV-Vis) and ESI-MS spectrometry. Density functional theory (DFT) was also used to better understand the structure of the complexes. The hydrolytic activity of complexes 1, 2 and 3 was analyzed using both the model substrate 2,4-BDNPP (bis-(2,4-dinitrophenyl)phosphate) and DNA. Complexes 2 and 3, containing the derivatized ligands, have a significantly higher association constant (Kassoc≅ 1/KM) for the activated substrate 2,4-BDNPP compared to complex 1. The catalytic efficiency (kcat/KM) is also higher due to hydrogen bonds and/or π-stacking interactions between the substrate and the aminoguanidine or aminopurine groups present in 2 and 3, respectively. In the DNA cleavage assays, all complexes were able to cleave DNA, with 1 and 2 having higher catalytic activity than 3. In addition, when compared to previously analyzed complexes, complex 2 is one of the most active, having a kcat of 0.21 h-1.

New Heteroleptic Ruthenium(II) Complexes with Sulfamethoxypyridazine and Diimines as Potential Antitumor Agents.

Two new complexes of Ru(II) with mixed ligands were prepared: [Ru(bpy)2smp](PF6) (1) and [Ru(phen)2smp](PF6) (2), in which smp = sulfamethoxypyridazine; bpy = 2,2'-bipyridine; phen = 1,10-phenanthroline. The complexes have been characterized by elemental and conductivity analyses; infrared, NMR, and electrospray ionization mass spectroscopies; and X-ray diffraction of single crystal. Structural analyses reveal a distorted octahedral geometry around Ru(II) that is bound to two bpy (in 1) or two phen (in 2) via their two heterocyclic nitrogens and to two nitrogen atoms from sulfamethoxypyridazine-one of the methoxypyridazine ring and the sulfonamidic nitrogen, which is deprotonated. Both complexes inhibit the growth of chronic myelogenous leukemia cells. The interaction of the complexes with bovine serum albumin and DNA is described. DNA footprinting using an oligonucleotide as substrate showed the complexes' preference for thymine base rich sites. It is worth notifying that the complexes interact with the Src homology SH3 domain of the Abl tyrosine kinase protein. Abl protein is involved in signal transduction and implicated in the development of chronic myelogenous leukemia. Nuclear magnetic resonance (NMR) studies of the interaction of complex 2 with the Abl-SH3 domain showed that the most affected residues were T79, G97, W99, and Y115.

Synthetic thiosemicarbazones as a new class of Mycobacterium tuberculosis protein tyrosine phosphatase A inhibitors.

Mycobacterium tuberculosis secretes two protein tyrosine phosphatases as virulence factors, PtpA and PtpB. Inhibition studies of these enzymes have shown significant attenuation of the M. tuberculosis growth in vivo. As PtpA mediates many effects on the regulation of host signaling ensuring the intracellular survival of the bacterium we report, for the first time, thiosemicarbazones as potential novel class of PtpA inhibitors. Several compounds were synthesized and biologically evaluated, revealing interesting results. Enzyme kinetic assays showed that compounds 5, 9 and 18 are non-competitive inhibitors of PtpA, with Ki values ranging from 1.2 to 5.6 µM. Modeling studies clarified the structure-activity relationships observed in vitro and indicated a possible allosteric binding site in PtpA structure. To the best of our knowledge, this is the first disclosure of potent non-competitive inhibitors of PtpA with great potential for future studies and development of analogues.

Posttranslational Chemical Mutagenesis: To Reveal the Role of Noncatalytic Cysteine Residues in Pathogenic Bacterial Phosphatases.

The field of chemical site-selective modification of proteins has progressed extensively in recent decades to enable protein functionalization for imaging, drug delivery, and functional studies. In this Perspective, we provide detailed insight into an alternative use of site-selective protein chemistry to probe the role(s) of unpaired Cys residues in the structure and function of disease relevant proteins. Phosphatases are important players in the successful infection of pathogenic bacteria, which represent a significant health burden, particularly in multi-drug-resistant strains. Therefore, a strategy for readily probing the key amino acid role(s) in structure and function may facilitate the targeting and inhibition of these virulence factors. With a dehydroalanine-based posttranslational chemical mutagenesis approach, it is possible to reveal hitherto unknown function(s) of noncatalytic Cys residues and confirm their role and interplay in pathogenic bacterial phosphatases. By selectively modifying reactive sulfhydryl side chains in different protein local environments, this posttranslational site-selective chemical mutagenesis approach reveals structural information about binding pockets and regulatory roles of the modified residues, which can be further validated by conventional site-directed mutagenesis. Ultimately, these new binding pockets can serve as templates for enhanced structure-based drug design platforms and aid the development of potent and specific inhibitors.

S-Nitrosylation of cIAP1 Switches Cancer Cell Fate from TNFα/TNFR1-Mediated Cell Survival to Cell Death.

TNFα is a prominent proinflammatory cytokine and a critical mediator for the development of many types of cancer such as breast, colon, prostate, cervical, skin, liver, and chronic lymphocytic leukemia. Binding of TNFα to TNFR1 can lead to divergent signaling pathways promoting predominantly NF-κB activation but also cell death. We report here that the nitric oxide (NO) donor glyceryl trinitrate (GTN) converts TNFα, generated from immune cells or cancer cells stimulated by chemotherapy, into a prodeath mediator in colon and mammary cancer cells. GTN-mediated S-nitrosylation of cIAP1 on cysteines 571 and 574 inhibited its E3 ubiquitin ligase activity, which in turn reduced Lys63-linked ubiquitination of RIP1 and initiated assembly of a death complex. These findings provide insights into how NO can harness advantageous aspects of inflammation in cancer and provide new therapeutic strategies.Significance: Combination of an NO donor with chemotherapeutic drug-induced TNFα represents a potentially valuable anticancer strategy. Cancer Res; 78(8); 1948-57. ©2018 AACR.

Second-Sphere Effects in Dinuclear FeIIIZnII Hydrolase Biomimetics: Tuning Binding and Reactivity Properties.

Herein, we report the synthesis and characterization of two dinuclear FeIIIZnII complexes [FeIIIZnIILP1] (1) and [FeIIIZnIILP2] (2), in which LP1 and LP2 are conjugated systems containing one and two pyrene groups, respectively, connected via the diamine -HN(CH2)4NH- spacer to the well-known N5O2-donor H2L ligand (H2L = 2-bis{[(2-pyridylmethyl)aminomethyl]-6-[(2-hydroxybenzyl)(2-pyridylmethyl)]aminomethyl}-4-methylphenol). The complex [FeIIIZnIIL1] (3), in which H2L was modified to H2L1, with a carbonyl group attached to the terminal phenol group, was included in this study for comparison purposes.1 Both complexes 1 and 2 were satisfactorily characterized in the solid state and in solution. Extended X-ray absorption fine structure data for 1 and 3 in an acetonitrile solution show that the multiply bridged structure seen in the solid state of 3 is retained in solution. Potentiometric and UV-vis titration of 1 and 2 show that electrostatic interaction between the protonated amino groups and coordinated water molecules significantly decreases the pKa of the iron(III)-bound water compared to those of 3. On the other hand, catalytic activity studies using 1 and 2 in the hydrolysis of the activated substrate bis(2,4-dinitrophenyl)phosphate (BDNPP) resulted in a significant increase in the association of the substrate (Kass ≅ 1/KM) compared to that of 3 because of electrostatic and hydrophobic interactions between BDNPP and the side-chain diaminopyrene of the ligands H2LP1 and H2LP2. In addition, the introduction of the pyrene motifs in 1 and 2 enhanced their activity toward DNA and as effective antitumor drugs, although the biochemical mechanism of the latter effect is currently under investigation. These complexes represent interesting examples of how to promote an increase in the activity of traditional artificial metal nucleases by introducing second-coordination-sphere effects.

Naturally occurring Diels-Alder-type adducts from Morus nigra as potent inhibitors of Mycobacterium tuberculosis protein tyrosine phosphatase B.

Mycobacterium tuberculosis (Mtb) protein tyrosine phosphatases A and B (PtpA and PtpB) have been recognized as potential molecular targets for the development of new therapeutic strategies against tuberculosis (TB). In this context, we have recently reported that the naturally occurring Diels-Alder-type adduct Kuwanol E is an inhibitor of PtpB (Ki = 1.6 ± 0.1 µM). Here, we describe additional Diels-Alder-type adducts isolated from Morus nigra roots bark that inhibit PtpB at sub-micromolar concentrations. The two most potent compounds, namely Kuwanon G and Kuwanon H, showed Ki values of 0.39 ± 0.27 and 0.20 ± 0.01 µM, respectively, and interacted with the active site of the enzyme as suggested by kinetics and mass spectrometry studies. Molecular docking coupled with intrinsic fluorescence analysis and isothermal titration calorimetry (ITC) further characterized the interaction of these promising PtpB inhibitors. Notably, in an Mtb survival assay inside macrophages, Kuwanon G showed inhibition of Mtb growth by 61.3%. All these results point to the common Diels-Alder-type adduct scaffold, and highlight its relevance for the development of PtpB inhibitors as candidate therapeutics for TB.

The therapeutic value of protein (de)nitrosylation in experimental septic shock.

Cardiovascular dysfunction and organ damage are hallmarks of sepsis and septic shock. Protein S-nitrosylation by nitric oxide has been described as an important modifier of protein function. We studied whether protein nitrosylation/denitrosylation would impact positively in hemodynamic parameters of septic rats. Polymicrobial sepsis was induced by cecal ligation and puncture. Female Wistar rats were treated with increasing doses of DTNB [5,5'-dithio-bis-(2-nitrobenzoic acid)] 30min before or 4 or 12h after sepsis induction. Twenty-four hours after surgery the following data was obtained: aorta response to phenylephrine, mean arterial pressure, vascular reactivity to phenylephrine, biochemical markers of organ damage, survival and aorta protein nitrosylation profile. Sepsis substantially decreases blood pressure and the response of aorta rings and of blood pressure to phenylephrine, as well as increased plasma levels of organ damage markers, mortality of 60% and S-nitrosylation of aorta proteins increased during sepsis. Treatment with DTNB 12h after septic shock induction reversed the loss of response of aorta rings and blood pressure to vasoconstrictors, reduced organ damage and protein nitrosylation and increased survival to 80%. Increases in protein S-nitrosylation are related to cardiovascular dysfunction and multiple organ injury during sepsis. Treatment of rats with DTNB reduced the excessive protein S-nitrosylation, including that in calcium-dependent potassium channels (BKCa), reversed the cardiovascular dysfunction, improved markers of organ dysfunction and glycemic profile and substantially reduced mortality. Since all these beneficial consequences were attained even if DTNB was administered after septic shock onset, protein (de)nitrosylation may be a suitable target for sepsis treatment.