From Proteome to Potential Drugs: Integration of Subtractive Proteomics and Ensemble Docking for Drug Repurposing against Pseudomonas aeruginosa RND Superfamily Proteins.

Pseudomonas aeruginosa (P. aeruginosa) poses a significant threat as a nosocomial pathogen due to its robust resistance mechanisms and virulence factors. This study integrates subtractive proteomics and ensemble docking to identify and characterize essential proteins in P. aeruginosa, aiming to discover therapeutic targets and repurpose commercial existing drugs. Using subtractive proteomics, we refined the dataset to discard redundant proteins and minimize potential cross-interactions with human proteins and the microbiome proteins. We identified 12 key proteins, including a histidine kinase and members of the RND efflux pump family, known for their roles in antibiotic resistance, virulence, and antigenicity. Predictive modeling of the three-dimensional structures of these RND proteins and subsequent molecular ensemble-docking simulations led to the identification of MK-3207, R-428, and Suramin as promising inhibitor candidates. These compounds demonstrated high binding affinities and effective inhibition across multiple metrics. Further refinement using non-covalent interaction index methods provided deeper insights into the electronic effects in protein-ligand interactions, with Suramin exhibiting superior binding energies, suggesting its broad-spectrum inhibitory potential. Our findings confirm the critical role of RND efflux pumps in antibiotic resistance and suggest that MK-3207, R-428, and Suramin could be effectively repurposed to target these proteins. This approach highlights the potential of drug repurposing as a viable strategy to combat P. aeruginosa infections.

Binding studies of a putative C. pseudotuberculosis target protein from Vitamin B12 Metabolism.

Vitamin B12 acts as a cofactor for various metabolic reactions important in living organisms. The Vitamin B12 biosynthesis is restricted to prokaryotes, which means, all eukaryotic organisms must acquire this molecule through diet. This study presents the investigation of Vitamin B12 metabolism and the characterization of precorrin-4 C(11)-methyltransferase (CobM), an enzyme involved in the biosynthesis of Vitamin B12 in Corynebacterium pseudotuberculosis. The analysis of the C. pseudotuberculosis genome identified two Vitamin B12-dependent pathways, which can be strongly affected by a disrupted vitamin metabolism. Molecular dynamics, circular dichroism, and NMR-STD experiments identified regions in CobM that undergo conformational changes after s-adenosyl-L-methionine binding to promote the interaction of precorrin-4, a Vitamin B12 precursor. The binding of s-adenosyl-L-methionine was examined along with the competitive binding of adenine, dATP, and suramin. Based on fluorescence spectroscopy experiments the dissociation constant for the four ligands and the target protein could be determined; SAM (1.4 ± 0.7 µM), adenine (17.8 ± 1.5 µM), dATP (15.8 ± 2.0 µM), and Suramin (6.3 ± 1.1 µM). The results provide rich information for future investigations of potential drug targets within the C. pseudotuberculosis's Vitamin B12 metabolism and related pathways to reduce the pathogen's virulence in its hosts.

Purinergic Antagonist Suramin Aggravates Myocarditis and Increases Mortality by Enhancing Parasitism, Inflammation, and Reactive Tissue Damage in Trypanosoma cruzi-Infected Mice.

Suramin (Sur) acts as an ecto-NTPDase inhibitor in Trypanosoma cruzi and a P2-purinoceptor antagonist in mammalian cells. Although the potent antitrypanosomal effect of Sur has been shown in vitro, limited evidence in vivo suggests that this drug can be dangerous to T. cruzi-infected hosts. Therefore, we investigated the dose-dependent effect of Sur-based chemotherapy in a murine model of Chagas disease. Seventy uninfected and T. cruzi-infected male C57BL/6 mice were randomized into five groups: SAL = uninfected; INF = infected; SR5, SR10, and SR20 = infected treated with 5, 10, or 20 mg/kg Sur. In addition to its effect on blood and heart parasitism, the impact of Sur-based chemotherapy on leucocytes myocardial infiltration, cytokine levels, antioxidant defenses, reactive tissue damage, and mortality was analyzed. Our results indicated that animals treated with 10 and 20 mg/kg Sur were disproportionally susceptible to T. cruzi, exhibiting increased parasitemia and cardiac parasitism (amastigote nests and parasite load (T. cruzi DNA)), intense protein, lipid and DNA oxidation, marked myocarditis, and mortality. Animals treated with Sur also exhibited reduced levels of nonprotein antioxidants. However, the upregulation of catalase, superoxide dismutase, and glutathione-S-transferase was insufficient to counteract reactive tissue damage and pathological myocardial remodeling. It is still poorly understood whether Sur exerts a negative impact on the purinergic signaling of T. cruzi-infected host cells. However, our findings clearly demonstrated that through enhanced parasitism, inflammation, and reactive tissue damage, Sur-based chemotherapy contributes to aggravating myocarditis and increasing mortality rates in T. cruzi-infected mice, contradicting the supposed relevance attributed to this drug for the treatment of Chagas disease.

Structural and functional characterization of suramin-bound MjTX-I from Bothrops moojeni suggests a particular myotoxic mechanism.

Local myonecrosis is the main event resulting from snakebite envenomation by the Bothrops genus and, frequently, it is not efficiently neutralized by antivenom administration. Proteases, phospholipases A2 (PLA2) and PLA2-like toxins are found in venom related to muscle damage. Functional sites responsible for PLA2-like toxins activity have been proposed recently; they consist of a membrane docking-site and a membrane rupture-site. Herein, a combination of functional, biophysical and crystallographic techniques was used to characterize the interaction between suramin and MjTX-I (a PLA2-like toxin from Bothrops moojeni venom). Functional in vitro neuromuscular assays were performed to study the biological effects of the protein-ligand interaction, demonstrating that suramin neutralizes the myotoxic effect of MjTX-I. Calorimetric assays showed two different binding events: (i) inhibitor-protein interactions and (ii) toxin oligomerization processes. These hypotheses were also corroborated with dynamic light and small angle X-ray scattering assays. The crystal structure of the MjTX-I/suramin showed a totally different interaction mode compared to other PLA2-like/suramin complexes. Thus, we suggested a novel myotoxic mechanism for MjTX-I that may be inhibited by suramin. These results can further contribute to the search for inhibitors that will efficiently counteract local myonecrosis in order to be used as an adjuvant of conventional serum therapy.

Corneal Neovascularization: A Combined Approach of Bevacizumab and Suramin Showed Increased Antiangiogenic Effect Through Downregulation of BFGF and P2X2.

PURPOSE: The objective is to analyze the antiangiogenic mechanism of suramab, a pharmaceutical compound of bevacizumab and suramin, in a rabbit model of corneal angiogenesis. MATERIAL AND METHODS: Corneal neovascularization was induced in four groups of six New Zealand White rabbits by applying a filter paper disk soaked in 1 M Na (OH) on the central cornea. Group one was treated after injury with intravenous suramab at a dose equivalent to 3 mg/kg of bevacizumab and 10 mg/kg of suramin. Group two was treated with intravenous bevacizumab (5 mg/kg). Group three was treated with 10 mg/kg of suramin while the control group received no treatment. Digital photographs were taken at days 9, 15, 21, and 35. Neovessel formation was quantified giving a 0-4 score to each quadrant according to the centripetal growth of the longest vessel (neovessel index, NVI). Animals were sacrificed at day 35. Corneas were processed for histology, immunohistochemistry, and Western-blot using primary antibodies against P2X2, basic fibroblast growth factor (bFGF), LYVE-1, PECAM-1, and vascular endothelial growth factor-A (VEGF-A). RESULTS: Suramab significantly reduced neovessel growth (mean NVI: 4.2) compared to bevacizumab (8.4), suramin (7.22), and control animals (12.2) at 35 days post-injury (p < 0.01). A lower protein expression of P2X2, bFGF, LYVE-1, PECAM-1, and VEGF-A was found in the cornea of suramab animals than in the other groups of animals. CONCLUSIONS: Joint downregulation of bFGF, P2X2, bFGF, and LYVE-1 constitutes a mechanism that induces greater and longer inhibition of corneal angiogenesis. Results might be relevant to ophthalmic care. Ocular administration of suramab is currently being investigated.

PLA2-like proteins myotoxic mechanism: a dynamic model description.

Phospholipase A2-like (PLA2-like) proteins contribute to the development of muscle necrosis in Viperidae snake bites and are not efficiently neutralized by current antivenom treatments. The toxic mechanisms of PLA2-like proteins are devoid of catalytic activity and not yet fully understood, although structural and functional experiments suggest a dimeric assembly and that the C-terminal residues are essential to myotoxicity. Herein, we characterized the functional mechanism of bothropic PLA2-like structures related to global and local measurements using the available models in the Protein Data Bank and normal mode molecular dynamics (NM-MD). Those measurements include: (i) new geometric descriptions between their monomers, based on Euler angles; (ii) characterizations of canonical and non-canonical conformations of the C-terminal residues; (iii) accessibility of the hydrophobic channel; (iv) inspection of ligands; and (v) distance of clustered residues to toxin interface of interaction. Thus, we described the allosteric activation of PLA2-like proteins and hypothesized that the natural movement between monomers, calculated from NM-MD, is related to their membrane disruption mechanism, which is important for future studies of the inhibition process. These methods and strategies can be applied to other proteins to help understand their mechanisms of action.

P2 purinergic receptor antagonists disrupt maternal behavior in lactating rats.

The involvement of purinergic signaling in several brain functions has been recognized, but the modulation on maternal behavior by the purinergic system is not established, even though there are functional interactions between the purinergic and oxytocinergic systems. Therefore, the aim of our study was to investigate whether central administration of P2 receptor antagonists affected the maternal behavior of lactating rats and c-Fos immunoreactivity in the forebrain. On day 7 of lactation, female rats were treated with vehicle (5µL; i.c.v.), suramin (9.4-75.0µg/5µL; i.c.v.) or PPADS (9.4-75.0µg/5µL; i.c.v.) 30min before the experiment began. The maternal behavior was evaluated during the 30min following suramin or PPADS administration. In addition, c-Fos-positive nuclei were counted in the medial preoptic area (MPOA) and in the bed nucleus of the stria terminalis (BNST), and neurons that were double-labeled for c-Fos/OT were counted in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus of lactating rats. The results show that P2 receptor antagonists decreased maternal care and decreased neuronal activation in the MPOA and BNST and activation of oxytocinergic neurons in hypothalamic nuclei. Our results indicate that the purinergic system modulates maternal behavior and neuronal activation induced by suckling during lactation.

Characterization of E-NTPDase (EC 3.6.1.5) activity in hepatic lymphocytes: A different activity profile from peripheral lymphocytes.

The activity of ectonucleoside triphosphate diphosphohydrolase (E-NTPDase; EC 3.6.1.5) was characterized in hepatic lymphocytes (HL) of rats. For this purpose, a specific method for the isolation of lymphocytes from hepatic tissue was developed. Subsequently, E-NTPDase activity of rat HL was compared with that of rat peripheral lymphocytes. The HL showed high cell count and viability. Also, the characterization test revealed that the optimal E-NTPDase activities were attained at 37°C and pH 8.0 in the presence of Ca2+ . In addition, in the presence of specific E-NTPDase inhibitors (20mM sodium azide and 0.3mM suramin), there were significant inhibitions in nucleotide hydrolysis. However, there was no significant change in adenosine triphosphate (ATP) or adenosine diphosphate (ADP) hydrolysis in the presence of inhibitors of other E-ATPase (0.1mM Ouabain, 0.5mM orthovanadate, and 1mM, 5mM, and 10mM sodium azide). Furthermore, the kinetic behavior of the enzyme in HL showed apparent Km of 134.90 ± 0.03µM and 214.40 ± 0.06µM as well as Vmax of 345.0 ± 28.32 and 242.0 ± 27.55 Æžmol Pi/min/mg of protein for ATP and ADP, respectively. The Chevillard plot revealed that ATP and ADP were hydrolyzed at the same active site of the enzyme. Our results suggest that the degradation of extracellular nucleotides in HL may have been primarily accomplished by E-NTPDase. The higher E-NTPDase activity observed in HL may be attributed to the important physiological functions of ATP and ADP in HL. SIGNIFICANCE OF THE STUDY: Extracellular purine nucleotides are able to interact with specific receptors and trigger a number of important physiological functions in cells. This interaction is controlled by ectonucleoside triphosphate diphosphohydrolase (E-NTPDase), enzyme that present their catalytic site at the extracellular space and degrades nucleotides. This purinergic signaling has important functions in peripheral lymphocytes and may represent an important new therapeutic target for the treatment of immunological diseases. However, there is dearth of information on the involvement of E-NTPDase in liver lymphocytes. The liver is an important organ, which performs both metabolic and toxicological roles in living organism, and hepatic lymphocytes may play crucial action in the regulation of immune responses in the liver tissue. Furthermore, various chronic diseases such as cirrhosis may be treated with novel pharmacotherapy by targeting the modulation of hepatic lymphocytes. Thus, the significance of this study is to evaluate the activity of E-NTPDase in liver lymphocyte and compare its activity with the peripheral lymphocytes.

Potential Implications for Designing Drugs Against the Brown Spider Venom Phospholipase-D.

Loxoscelism refers to the clinical symptoms that develop after brown spider bites. Brown spider venoms contain several phospholipase-D isoforms, which are the main toxins responsible for both the cutaneous and systemic effects of loxoscelism. Understanding of the phospholipase-D catalytic mechanism is crucial for the development of specific treatment that could reverse the toxic effects caused by the spider bite. Based on enzymatic, biological, structural, and thermodynamic tests, we show some features suitable for designing drugs against loxoscelism. Firstly, through molecular docking and molecular dynamics predictions, we found three different molecules (Suramin, Vu0155056, and Vu0359595) that were able to bind the enzyme's catalytic site and interact with catalytically important residues (His12 or His47) and with the Mg2+ co-factor. The binding promoted a decrease in the recombinant brown spider venom phospholipase-D (LiRecDT1) enzymatic activity. Furthermore, the presence of the inhibitors reduced the hemolytic, dermonecrotic, and inflammatory activities of the venom toxin in biological assays. Altogether, these results indicate the mode of action of three different LiRecDT1 inhibitors, which were able to prevent the venom toxic effects. This strengthen the idea of the importance of designing a specific drug to treat the serious clinical symptoms caused by the brown spider bite, a public health problem in several parts of the world, and until now without specific treatment. J. Cell. Biochem. 118: 726-738, 2017. © 2016 Wiley Periodicals, Inc.

P2Y2 purinergic receptors are highly expressed in cardiac and diaphragm muscles of mdx mice, and their expression is decreased by suramin.

INTRODUCTION: In Duchenne muscular dystrophy (DMD) and in the mdx mouse model of DMD, the lack of dystrophin leads to increased calcium influx and muscle necrosis. Patients suffer progressive muscle loss, and cardiomyopathy is an important determinant of morbidity. P2 purinergic receptors participate in the increased calcium levels in dystrophic skeletal muscles. METHODS: In this study, we evaluated whether P2 receptors are involved in cardiomyopathy in mdx mice at later stages of the disease. RESULTS: Western blotting revealed that P2Y2 receptor levels were upregulated (54%) in dystrophic heart compared with a normal heart. Suramin reduced the levels of P2Y2 to almost normal values. Suramin also decreased heart necrosis (reduced CK-MB) and the expression of the stretch-activated calcium channel TRPC1. CONCLUSIONS: This study suggests that P2Y2 may participate in cardiomyopathy in mdx mice. P2-selective drugs with specific actions in the dystrophic heart may ameliorate cardiomyopathy in dystrophinopathies. Muscle Nerve 55: 116-121, 2017.

Structural and functional evidence for membrane docking and disruption sites on phospholipase A2-like proteins revealed by complexation with the inhibitor suramin.

Local myonecrosis resulting from snakebite envenomation is not efficiently neutralized by regular antivenom administration. This limitation is considered to be a significant health problem by the World Health Organization. Phospholipase A2-like (PLA2-like) proteins are among the most important proteins related to the muscle damage resulting from several snake venoms. However, despite their conserved tertiary structure compared with PLA2s, their biological mechanism remains incompletely understood. Different oligomeric conformations and binding sites have been identified or proposed, leading to contradictory data in the literature. In the last few years, a comprehensive hypothesis has been proposed based on fatty-acid binding, allosteric changes and the presence of two different interaction sites. In the present study, a combination of techniques were used to fully understand the structural-functional characteristics of the interaction between suramin and MjTX-II (a PLA2-like toxin). In vitro neuromuscular studies were performed to characterize the biological effects of the protein-ligand interaction and demonstrated that suramin neutralizes the myotoxic activity of MjTX-II. The high-resolution structure of the complex identified the toxin-ligand interaction sites. Calorimetric assays showed two different binding events between the protein and the inhibitor. It is demonstrated for the first time that the inhibitor binds to the surface of the toxin, obstructing the sites involved in membrane docking and disruption according to the proposed myotoxic mechanism. Furthermore, higher-order oligomeric formation by interaction with interfacial suramins was observed, which may also aid the inhibitory process. These results further substantiate the current myotoxic mechanism and shed light on the search for efficient inhibitors of the local myonecrosis phenomenon.

Concomitant Benznidazole and Suramin Chemotherapy in Mice Infected with a Virulent Strain of Trypanosoma cruzi.

Although suramin (Sur) is suggested as a potential drug candidate in the management of Chagas disease, this issue has not been objectively tested. In this study, we examined the applicability of concomitant treatment with benznidazole (Bz) and suramin in mice infected with a virulent strain of Trypanosoma cruzi. Eighty 12-week-old male C57BL/6 mice were equally randomized in eight groups: (i) noninfected mice (negative control) and mice infected with T. cruzi Y strain receiving (ii) no treatment (positive control), (iii) Bz, 100 mg/kg of body weight per day, (iv) Sur, 20 mg/kg/day, and (v to viii) Sur, 20 mg/kg/day, combined with Bz, 100, 50, 25, or 5 mg/kg/day. Bz was administered by gavage, and Sur was administered intraperitoneally. Sur dramatically increased the parasitemia, cardiac content of parasite DNA, inflammation, oxidative tissue damage, and mortality. In response to high parasitic load in cardiac tissue, Sur stimulated the immune system in a manner typical of the acute phase of Chagas disease, increasing tissue levels of gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) and inducing a preferential IgG2a anti-T. cruzi serum pattern. When Sur and Bz were combined, the infection severity was attenuated, showing a dose-dependent Bz response. Sur therapy had a more harmful effect on the host than on the parasite and reduced the efficacy of Bz against T. cruzi infection. Considering that Sur drastically reinforced the infection evolution, potentiating the inflammatory process and the severity of cardiac lesions, the in vivo findings contradicted the in vitro anti-T. cruzi potential described for this drug.

Involvement of nucleotides in glial growth following scratch injury in avian retinal cell monolayer cultures.

When retinal cell cultures were mechanically scratched, cell growth over the empty area was observed. Only dividing and migrating, 2 M6-positive glial cells were detected. Incubation of cultures with apyrase (APY), suramin, or Reactive Blue 2 (RB-2), but not MRS 2179, significantly attenuated the growth of glial cells, suggesting that nucleotide receptors other than P2Y1 are involved in the growth of glial cells. UTPγS but not ADPßS antagonized apyrase-induced growth inhibition in scratched cultures, suggesting the participation of UTP-sensitive receptors. No decrease in proliferating cell nuclear antigen (PCNA(+)) cells was observed at the border of the scratch in apyrase-treated cultures, suggesting that glial proliferation was not affected. In apyrase-treated cultures, glial cytoplasm protrusions were smaller and unstable. Actin filaments were less organized and alfa-tubulin-labeled microtubules were mainly parallel to scratch. In contrast to control cultures, very few vinculin-labeled adhesion sites could be noticed in these cultures. Increased Akt and ERK phosphorylation was observed in UTP-treated cultures, effect that was inhibited by SRC inhibitor 1 and PI3K blocker LY294002. These inhibitors and the FAK inhibitor PF573228 also decreased glial growth over the scratch, suggesting participation of SRC, PI3K, and FAK in UTP-induced growth of glial cells in scratched cultures. RB-2 decreased dissociated glial cell attachment to fibronectin-coated dishes and migration through transwell membranes, suggesting that nucleotides regulated adhesion and migration of glial cells. In conclusion, mechanical scratch of retinal cell cultures induces growth of glial cells over the empty area through a mechanism that is dependent on activation of UTP-sensitive receptors, SRC, PI3K, and FAK.

The phosphoglycerate kinase isoenzymes have distinct roles in the regulation of carbohydrate metabolism in Trypanosoma cruzi.

The glycolytic enzyme phosphoglycerate kinase (PGK) is present in Trypanosoma cruzi as three isoenzymes, two of them located inside glycosomes (PGKA and PGKC) and another one in the cytosol (PGKB). The three isoenzymes are expressed at all stages of the life cycle of the parasite. A heterologous expression system for PGKA (rPGKA) was developed and the substrate affinities of the natural and recombinant PGKA isoenzyme were determined. Km values measured for 3-phosphoglycerate (3PGA) were 174 and 850 µM, and for ATP 217 and 236 µM, for the natural and recombinant enzyme, respectively. No significant differences were found between the two forms of the enzyme. The rPGKA was inhibited by Suramin with Ki values of 10.08 µM and 12.11 µM for ATP and 3PGA, respectively, and the natural enzyme was inhibited at similar values. A site-directed mutant was created in which the 80 amino acids PGKA sequence, present as a distinctive insertion in the N-terminal domain, was deleted. This internally truncated PGKA showed the same Km values and specific activity as the full-length rPGKA. The natural PGKC isoenzyme was purified from epimastigotes and separated from PGKA through molecular exclusion chromatography and its kinetic characteristics were determined. The Km value obtained for 3PGA was 192 µM, and 10 µM for ATP. Contrary to PGKA, the activity of PGKC is tightly regulated by ATP (substrate inhibition) with a Ki of 270 µM, suggesting a role for this isoenzyme in regulating metabolic fluxes inside the glycosomes.

ADP is a vasodilator component from Lasiodora sp. mygalomorph spider venom.

Members of the spider genus Lasiodora are widely distributed in Brazil, where they are commonly known as caranguejeiras. Lasiodora spider venom is slightly harmful to humans. The bite of this spider causes local pain, edema and erythema. However, Lasiodora sp. spider venom may be a source of important pharmacological tools. Our research group has described previously that Lasiodora sp. venom produces bradycardia in the isolated rat heart. In the present work, we sought to evaluate the vascular effect of Lasiodora sp. venom and to isolate the vasoactive compounds from the venom. The results showed that Lasiodora spider venom induced a concentration-dependent vasodilation in rat aortic rings, which was dependent on the presence of a functional endothelium and abolished by the nitric oxide synthase (NOS) inhibitor L-NAME. Western blot experiments revealed that the venom also increased endothelial NOS function by increasing phosphorylation of the Ser¹¹77 residue. Assay-directed fractionation isolated a vasoactive fraction from Lasiodora sp. venom. Mass spectrometry (MS) and nuclear magnetic resonance (NMR) assays identified a mixture of two compounds: adenosine diphosphate (ADP, approximately 90%) and adenosine monophosphate (AMP, approximately 10%). The vasodilator effects of Lasiodora sp. whole venom, as well as ADP, were significantly inhibited by suramin, which is a purinergic P2-receptor antagonist. Therefore, the results of the present work indicate that ADP is a main vasodilator component of Lasiodora sp. spider venom.

Falcipain-2 inhibition by suramin and suramin analogues.

Falcipain-2 is a cysteine protease of the malaria parasite Plasmodium falciparum that plays a key role in the hydrolysis of hemoglobin, a process that is required by intraerythrocytic parasites to obtain amino acids. In this work we show that the polysulfonated napthylurea suramin is capable of binding to falcipain-2, inhibiting its catalytic activity at nanomolar concentrations against both synthetic substrates and the natural substrate hemoglobin. Kinetic measurements suggest that the inhibition occurs through an noncompetitive allosteric mechanism, eliciting substrate inhibition. Smaller suramin analogues and those with substituted methyl groups also showed inhibition within the nanomolar range. Our results identify the suramin family as a potential starting point for the design of falcipain-2 inhibitor antimalarials that act through a novel inhibition mechanism.

Susceptibility of Brazilian isolates of Trypanosoma evansi to suramin sodium: test in experimentally infected mice.

This study aimed to evaluate the susceptibility of Brazilian isolates of Trypanosoma evansi to suramin sodium. For this purpose, three isolates of T. evansi (LPV-2005, LPV-2009 and LPV-2010) and seventy mice were used, with the animals divided in 10 groups (A, B, C, D, E, F, G, H, I and J) with seven animals each group. Mice of groups A, B, and C were infected with LPV-2005; Groups D, E and F with LPV-2009 and the groups G, H and I with LPV-2010. The group J was composed by healthy mice or uninfected. The parasitemia was monitored daily through blood smear, and the treatment of all groups was performed three days post-infection (PI), when all mice showed increased parasitemia. Groups A, D and G represented the positives controls, while groups B, E and H received a single dose of suramin sodium at 10 mgkg(-1) intramuscularly. Groups C, F and I were treated with three doses of suramin sodium at 10 mgkg(-1), respecting an interval of 24 h between each dose. Negative blood smears from all animals were obtained 24 h after treatment (AT), status maintained until the end of the experiment (50 days PI). The specific PCR for T. evansi was carried out from blood, showing negative results AT. Therefore, this study showed that a single dose of suramin sodium at 10 mgkg(-1) has the same efficacy of three doses, as recommended by the therapeutic literature. Furthermore, we observed that Brazilian isolates did not show resistance to the drug.

Suramin attenuates dystrophin-deficient cardiomyopathy in the mdx mouse model of duchenne muscular dystrophy.

INTRODUCTION: The purpose of this study was to determine the effects of suramin, an antifibrotic agent, on cardiac function and remodeling in mdx mice. METHODS: mdx mice (8 months old) received intraperitoneal injections of suramin twice a week for 3 months. Control mdx mice (8 months old) were injected with saline. RESULTS: Suramin improved the electrocardiography profile with the main corrections seen in S- to R-wave ratio, PR interval, and Q amplitude, and a significant decrease in the cardiomyopathy index. Suramin decreased myocardial fibrosis, inflammation, and myonecrosis. CONCLUSIONS: These findings suggest that suramin may be a new adjunctive therapy to help improve cardiomyopathy in DMD.

Neutralization of Apis mellifera bee venom activities by suramin.

In this work we evaluated the ability of suramin, a polysulfonated naphthylurea derivative, to antagonize the cytotoxic and enzymatic effects of the crude venom of Apis mellifera. Suramin was efficient to decrease the lethality in a dose-dependent way. The hemoconcentration caused by lethal dose injection of bee venom was abolished by suramin (30 µg/g). The edematogenic activity of the venom (0.3 µg/g) was antagonized by suramin (10 µg/g) in all treatment protocols. The changes in the vascular permeability caused by A. mellifera (1 µg/g) venom were inhibited by suramin (30 µg/g) in the pre- and posttreatment as well as when the venom was preincubated with suramin. In addition, suramin also inhibited cultured endothelial cell lesion, as well as in vitro myotoxicity, evaluated in mouse extensor digitorum longus muscle, which was inhibited by suramin (10 and 25 µM), decreasing the rate of CK release, showing that suramin protected the sarcolemma against damage induced by components of bee venom (2.5 µg/mL). Moreover, suramin inhibited the in vivo myotoxicity induced by i.m. injection of A. mellifera venom in mice (0.5 µg/g). The analysis of the area under the plasma CK vs. time curve showed that preincubation, pre- and posttreatment with suramin (30 µg/g) inhibited bee venom myotoxic activity in mice by about 89%, 45% and 40%, respectively. Suramin markedly inhibited the PLA2 activity in a concentration-dependent way (1-30 µM). Being suramin a polyanion molecule, the effects observed may be due to the interaction of its charges with the polycation components present in A. mellifera bee venom.

Suramin affects metalloproteinase-9 activity and increases ß-dystroglycan levels in the diaphragm of the dystrophin-deficient mdx mouse.

INTRODUCTION: In Duchenne muscular dystrophy and in the mdx mouse, muscle fiber degeneration and subsequent fibrosis lead to cardiorespiratory failure. Previously, we demonstrated that the anti-fibrotic agent suramin was effective in decreasing fibrosis in mdx muscles. In this study, we were interested to see whether suramin could affect metalloproteinases (MMP) and improve the functional activity of the mdx diaphragm muscle. METHODS: Zymography was performed to evaluate MMP-2 and MMP-9 activity. Western blotting was used to analyze the levels of beta-dystroglycan. Muscle function was assessed in hemidiaphragm in vitro preparations. RESULTS: We found that suramin affects metalloproteinase-9 activity and increases beta-dystroglycan. Furthermore, suramin also protects against diaphragm muscle fatigue over time. CONCLUSIONS: These results show the potential benefits of suramin in maintaining the structure of the dystrophin-glycoprotein complex.