RESUMO
Staphylococcus aureus is a highly virulent pathogen, capable of biofilm formation and responsible for thousands of deaths each year. The prevalence of Methicillin-Resistant S. aureus (MRSA) strains has increased in recent years and thus, the development of new antibiotics has become necessary. Antimicrobial Peptides (AMPs) are effective against a variety of multidrug-resistant bacteria and low levels of resistance have been reported regarding these molecules. Dinoponera quadriceps ant venom (DqV) has been described regarding its effect against S. aureus. In this study, we have evaluated the antibacterial effect of DqV-AMPs, the dinoponeratoxins (DNTxs), against Methicillin-Sensitive and a Methicillin-Resistant S. aureus strains. Our results show DNTx M-PONTX-Dq3a as a potent inhibitor of both strains, being able to prevent biofilm formation at low micromolar range (0.78-3.12 µM). It also showed a short-time effect through membrane disruption. M-PONTX-Dq3a opens up new perspectives for the prevention of biofilm formation through the development of anti-adhesive surface coatings on medical devices, as well as the treatment of resistant strains in skin or soft tissue infections.
Assuntos
Venenos de Formiga/farmacologia , Antibacterianos/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Animais , Humanos , Testes de Sensibilidade MicrobianaRESUMO
Biofilm formation on exposed surfaces is a serious issue for the food industry and medical health facilities. There are many proposed strategies to delay, reduce, or even eliminate biofilm formation on surfaces. The present study focuses on the applicability of fire ant venom alkaloids (aka 'solenopsins', from Solenopsis invicta) tested on polystyrene and stainless steel surfaces relative to the adhesion and biofilm-formation by the bacterium Pseudomonas fluorescens. Conditioning with solenopsins demonstrates significant reduction of bacterial adhesion. Inhibition rates were 62.7% on polystyrene and 59.0% on stainless steel surfaces. In addition, solenopsins drastically reduced cell populations already growing on conditioned surfaces. Contrary to assumptions by previous authors, solenopsins tested negative for amphipathic properties, thus understanding the mechanisms behind the observed effects still relies on further investigation.
Assuntos
Alcaloides/farmacologia , Venenos de Formiga/farmacologia , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Pseudomonas fluorescens/efeitos dos fármacos , Animais , Formigas , Aderência Bacteriana/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Poliestirenos , Pseudomonas fluorescens/fisiologia , Aço InoxidávelRESUMO
The venom peptide bicarinalin, previously isolated from the ant Tetramorium bicarinatum, is an antimicrobial agent with a broad spectrum of activity. In this study, we investigate the potential of bicarinalin as a novel agent against Helicobacter pylori, which causes several gastric diseases. First, the effects of synthetic bicarinalin have been tested against Helicobacter pylori: one ATCC strain, and forty-four isolated from stomach ulcer biopsies of Peruvian patients. Then the cytoxicity of bicarinalin on human gastric cells and murine peritoneal macrophages was measured using XTT and MTT assays, respectively. Finally, the preventive effect of bicarinalin was evaluated by scanning electron microscopy using an adherence assay of H. pylori on human gastric cells treated with bicarinalin. This peptide has a potent antibacterial activity at the same magnitude as four antibiotics currently used in therapies against H. pylori. Bicarinalin also inhibited adherence of H. pylori to gastric cells with an IC50 of 0.12 µg·mL-1 and had low toxicity for human cells. Scanning electron microscopy confirmed that bicarinalin can significantly decrease the density of H. pylori on gastric cells. We conclude that Bicarinalin is a promising compound for the development of a novel and effective anti-H. pylori agent for both curative and preventive use.
Assuntos
Venenos de Formiga/farmacologia , Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Helicobacter pylori/efeitos dos fármacos , Animais , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Helicobacter pylori/ultraestrutura , Humanos , Macrófagos Peritoneais/efeitos dos fármacos , Camundongos , Células RAW 264.7RESUMO
Natural products, sources of new pharmacological substances, have large chemical diversity and architectural complexity. In this context, some toxins obtained from invertebrate venoms have anticonvulsant effects. Epilepsy is a neurological disorder that affects about 65 million people worldwide, and approximately 30% of cases are resistant to pharmacological treatment. Previous studies from our group show that the denatured venom of the ant Dinoponera quadriceps (Kempt) protects mice against bicuculline (BIC)-induced seizures and death. The aim of this study was to investigate the anticonvulsant activity of compounds isolated from D. quadriceps venom against seizures induced by BIC in mice. Crude venom was fractionated by high-performance liquid chromatography (HPLC) resulting in six fractions referred to as DqTx1-DqTx6. A liquid chromatography-mass spectrometry (LC/MS) analysis revealed a major 431 Da compound in fractions DqTx1 and DqTx2. Fractions DqTx3 and DqTx4 showed a compound of 2451 Da and DqTx5 revealed a 2436 Da compound. Furthermore, the DqTx6 fraction exhibited a major component with a molecular weight of 13,196 Da. Each fraction (1 mg/mL) was microinjected into the lateral ventricle of mice, and the animals were observed in an open field. We did not observe behavioral alterations when the fractions were given alone. Conversely, when the fractions were microinjected 20 min prior to the administration of BIC (21.6 nM), DqTx1, DqTx4, and DqTx6 fractions increased the latency for onset of tonic-clonic seizures. Moreover, all fractions, except DqTx5, increased latency to death. The more relevant result was obtained with the DqTx6 fraction, which protected 62.5% of the animals against tonic-clonic seizures. Furthermore, this fraction protected 100% of the animals from seizure episodes followed by death. Taken together, these findings indicate that compounds from ant venom might be a potential source of new anticonvulsants molecules.
Assuntos
Venenos de Formiga/farmacologia , Anticonvulsivantes/farmacologia , Formigas , Convulsões/tratamento farmacológico , Animais , Venenos de Formiga/química , Anticonvulsivantes/química , Bicuculina , Modelos Animais de Doenças , Masculino , Camundongos , Convulsões/induzido quimicamenteRESUMO
Ants cause a series of accidents involving humans. Such accidents generate different reactions in the body, ranging from a mild irritation at the bite site to anaphylactic shock, and these reactions depend on the mechanism of action of the venom. The study of animal venom is a science known as venomics. Through venomics, the composition of the venom of several ant species has already been characterized and their biological activities described. Thus, the aim of this study was to evaluate the protein composition and biological activities (hemolytic and immunostimulatory) of the venom of Neoponera villosa (N. villosa), an ant widely distributed in South America. The protein composition was evaluated by proteomic techniques, such as two-dimensional electrophoresis. To assess the biological activity, hemolysis assay was carried out and cytokines were quantified after exposure of macrophages to the venom. The venom of N. villosa has a profile composed of 145 proteins, including structural and metabolic components (e.g., tubulin and ATPase), allergenic and immunomodulatory proteins (arginine kinase and heat shock proteins (HSPs)), protective proteins of venom (superoxide dismutase (SOD) and catalase) and tissue degradation proteins (hyaluronidase and phospholipase A2). The venom was able to induce hemolysis in human erythrocytes and also induced release of both pro-inflammatory cytokines, as the anti-inflammatory cytokine release by murine macrophages. These results allow better understanding of the composition and complexity of N. villosa venom in the human body, as well as the possible mechanisms of action after the bite.
Assuntos
Venenos de Formiga/farmacologia , Hemolíticos/farmacologia , Proteoma , Animais , Venenos de Formiga/química , Venenos de Formiga/isolamento & purificação , Formigas , Brasil , Células Cultivadas , Citocinas/metabolismo , Eritrócitos/efeitos dos fármacos , Humanos , Macrófagos/efeitos dos fármacos , CamundongosRESUMO
AIMS: Dinoponera quadriceps venom (DqV) was examined to evaluate the antibacterial activity and its bactericidal action mechanism against Staphylococcus aureus. METHODS AND RESULTS: DqV was tested against a standard strain of methicillin-sensitive Staphylococcus aureus (MSSA), Staph. aureus ATCC 6538P and two standard strains of methicillin-resistant Staphylococcus aureus (MRSA), Staph. aureus ATCC 33591 and Staph. aureus CCBH 5330. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), the rate of kill and pH sensitivity of the DqV were determined by microdilution tests. Bactericidal and inhibitory concentrations of DqV were tested to check its action on Staph. aureus membrane permeability and cell morphology. The MIC and MBC of DqV were 6·25 and 12·5 µg ml(-1) for Staph. aureus ATCC 6538P, 12·5 and 50 µg ml(-1) for Staph. aureus CCBH 5330 and 100 and 100 µg ml(-1) for Staph. aureus ATCC 33591, respectively. Complete bacterial growth inhibition was observed after 4 h of incubation with the MBC of DqV. A lowest MIC was observed in alkaline pH. Alteration in membrane permeability was observed through the increase in crystal violet uptake, genetic material release and morphology in atomic force microscopy. CONCLUSIONS: The results suggest antibacterial activity of DqV against Staph. aureus and that the venom acts in the cell membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: Alteration in membrane permeability may be associated with the antimicrobial activity of hymenopteran venoms.
Assuntos
Venenos de Formiga/farmacologia , Antibacterianos/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Animais , FormigasRESUMO
Arthropod venoms are potential sources of neuroactive substances, providing new tools for the design of drugs. The aim of this study was to evaluate the effects of Dinoponera quadriceps venom (DqV) on seizure models in mice induced by pentylenetetrazole (PTZ), pilocarpine, and strychnine. In the PTZ model, intraperitoneal treatment with DqV (0.5mg/kg) increased the time until the first seizure and the percentage of survival (155.4±27.7s/12.5%, p<0.05) compared to the control group (79.75±3.97s/0%), whereas endovenous treatment (0.1 and 0.5mg/kg) decreased the time until the first seizure (0.1mg/kg: 77.83±5.3s versus 101.0±3.3s in the control group; 0.5mg/kg: 74.43±3.9s versus 101.0±3.3s for the control group, p<0.05). We did not observe significant changes in the pilocarpine- and strychnine-induced seizure models. In assays that measured oxidative parameters in the PTZ model, intraperitoneal treatment with DqV (0.5 and 2.0mg/kg) only decreased the levels of MDA and nitrite in the cortex. However, endovenous treatment with DqV (0.1 and 0.5mg/kg) increased the levels of MDA in the cortex and hippocampus and at a dose of 0.5mg/kg in the striatum. Moreover, increased in nitrite content was observed in all three of the brain regions analyzed. Taken together, the D. quadriceps venom caused both neuroprotective and neurotoxic effects in a PTZ-induced seizure model, and this effect was dependent on the route of administration used.