ABSTRACT
Previously, it was shown that the non-conventional toxin WTX from the venom of the cobra Naja kaouthia, when administered intravenously, caused a decrease in blood pressure (BP) and an increase in heart rate (HR) in rats [13]. To identify the site of the toxin molecule responsible for these effects, we studied the influence of synthetic peptide fragments of the WTX on BP and HR in normotensive male Sprague-Dawley rats under general anesthesia induced by Telazol and Xylazine. It was found that peptides corresponding to the WTX central polypeptide loop, stabilized by a disulfide bond, at intravenous injection at concentrations from 0.1 to 1.0 mg/mL caused a dose-dependent decrease in BP, with the HR increasing only in the first 5-10 min after administration. Thus, WTX fragments corresponding to the central polypeptide loop reproduce the decrease in blood pressure caused by the toxin.
Subject(s)
Elapid Venoms , Peptides , Rats , Male , Animals , Blood Pressure , Amino Acid Sequence , Rats, Sprague-Dawley , Elapid Venoms/chemistry , Elapid Venoms/pharmacology , Peptides/pharmacology , Anesthesia, General , Peptide Fragments/pharmacologyABSTRACT
The effects of extracts of ten plant species from Russia and five species from Vietnam on the growth and survival of ciliates Tetrahymena pyriformis were studied. T. pyriformis belongs to the subkingdom Protozoa, which also includes pathogens of protozoan infections. Extraction of dried plants was carried out with acidic and alkaline aqueous solutions, as well as with an aqueous ethanol. Various amounts of extracts were added to the ciliate cells, and the number of cells survived after incubation for 1 and 24 h was recorded. We found that our samples of several plants, including wormwood, harmala, and licorice, similarly to those studied earlier, exhibit antiprotozoal activity, which may indicate that the secondary metabolites are the same in plants from different regions. Using the ciliate T. pyriformis as a model organism, the presence of antiprotozoal activity in extracts of lilac, chondrilla, cinquefoil, hop, and elm was shown for the first time.
Subject(s)
Antiprotozoal Agents , Plant Extracts , Plants , Russia , Plants/chemistry , Antiprotozoal Agents/chemistry , Antiprotozoal Agents/pharmacology , Plant Extracts/chemistry , Plant Extracts/pharmacology , Tetrahymena pyriformis/drug effectsABSTRACT
The data available to date indicate that the activation of nicotinic acetylcholine receptors (nAChR) of α7 type can reduce heart damage resulting from ischemia and subsequent reperfusion. We have studied two new synthetic D-analogs of 6-bromohypaphorine, which are selective agonists of α7 nAChR, in a rat model of myocardial ischemia. Acute myocardial infarction in animals was induced by occlusion of the left coronary artery with its subsequent reperfusion under mechanical lung ventilation. It was found that one of the analogs was more active, and treatment with it at the onset of reperfusion statistically reduced infarct size. This analog also prevented changes in the concentration of potassium and sodium ions in the blood, occurring during occlusion/reperfusion injury. The data obtained indicate that hypaphorine analogs are promising for the development of drugs that reduce the adverse effects of myocardial infarction.
Subject(s)
Heart Injuries , Myocardial Infarction , Myocardial Ischemia , Myocardial Reperfusion Injury , Receptors, Nicotinic , Animals , Myocardial Infarction/drug therapy , Myocardial Ischemia/drug therapy , Myocardial Reperfusion Injury/drug therapy , Myocardial Reperfusion Injury/prevention & control , Rats , Reperfusion , Tryptophan/analogs & derivativesABSTRACT
To search for compounds with antiprotozoal activity, effects of snake venoms on the ciliates Tetrahymena pyriformis was studied. T. pyriformis from subkingdom of Protozoa, including the protozoal pathogens, was used as a model organism to select the venoms that are the most active against parasitic protozoans. Various concentrations of venoms were added to the cells, and the cells that survived after 24 h were counted. Among the six snake species from the Viperidae family, the venom of the viper Vipera berus, which completely killed the cells at 49 µg/mL, was the most active. Among four species from the Elapidae family, the previously studied cobra venoms containing cytotoxins with strong antiprotozoal activity as well as the venom of krait Bungarus multicinctus (10 µg/mL) were the most active. The venoms of the pit vipers and Nikolsky's viper did not show any activity at 12.5 mg/mL. Thus, the venoms of V. berus and B. multicinctus are promising for the isolation of new antiprotozoal compounds.
Subject(s)
Tetrahymena pyriformis , Viperidae , Animals , Bungarus , Elapid Venoms , Elapidae , Snake Venoms , Viper VenomsABSTRACT
Blockade of α6, α3ß2, α9α10, and α7 subtypes of nicotinic acetylcholine receptors slows tumor growth in vivo, increases cytotoxic activity of splenocytes from tumor-bearing mice, and, to some extent, reduces the viability of Ehrlich carcinoma cells in vitro. These data indicate that nicotinic acetylcholine receptors are involved in oncogenesis, affecting the survival of tumor cells, inter alia, via modulation of the antitumor immunity.
Subject(s)
Antineoplastic Agents/pharmacology , Carcinoma, Ehrlich Tumor/metabolism , Nicotinic Antagonists/pharmacology , Spleen/cytology , Animals , Antineoplastic Agents/chemistry , Carcinogenesis , Cell Proliferation , Cell Survival , Conotoxins/metabolism , Mice , Neoplasm Transplantation , Nicotinic Antagonists/chemistry , Receptors, Nicotinic/metabolism , alpha7 Nicotinic Acetylcholine Receptor/antagonists & inhibitorsABSTRACT
Using electrophysiology, the effect of nicotinic acetylcholine receptor (nAChR) ligands on acetylcholine-induced depolarization in the neurons of Helix lucorum snail was studied. It was found that the α-conotoxin PnIA [R9, L10], a selective antagonist of α7 nAChR, and α-cobratoxin (antagonist of α7 and muscle-type nAChR) suppressed neuronal depolarization. Fluorescence microscopy showed staining of the neurons with fluorescently labeled α-bungarotoxin; this staining was reduced by pretreatment with α-cobratoxin. Induced depolarization was also suppressed by α-conotoxin RgIA, a selective inhibitor of α9 nAChR. In contrast to Lymnaea stagnalis nAChR, which are weakly sensitive to neurotoxin II and α-conotoxin GI, antagonists of muscle-type nAChR, H. lucorum receptors were most effectively inhibited by these antagonists. The results obtained, as well as the previously found sensitivity of the receptors studied in this work to muscarinic receptor ligands, indicate an unusual atypical pharmacological profile of H. lucorum nAChR.
Subject(s)
Neurons/metabolism , Receptors, Cholinergic/metabolism , alpha7 Nicotinic Acetylcholine Receptor/metabolism , Acetylcholine/metabolism , Animals , Binding Sites , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Bungarotoxins/metabolism , Helix, Snails , Ligands , Microscopy, Confocal , Microscopy, Fluorescence , Neurotoxins/metabolism , Pyridines/pharmacology , Signal TransductionABSTRACT
The study of the influence of cobra Naja oxiana cardiotoxins on the contractility of the rat papillary muscles and its rhythmoinotropic characteristics has shown that the presence of toxins induces a slight contractility decrease in the stimulation frequency range up to 0.1 Hz. In the stimulation frequency range from 0.1 to 0.5 Hz, a positive inotropic effect is found. However, the positive inotropic effect is replaced by a negative one with further increase in the frequency up to 3 Hz. In the presence of cardiotoxins, the positive force-frequency relationship in the region of 1-3 Hz, characteristic of healthy rat myocardium, disappears and the relationship becomes completely negative. L-type calcium channel blocker nifedipine does not affect the changes induced by toxins, while a high concentration (10 mM) of calcium prevents the effects of cardiotoxins on the muscle. The results obtained show that the impairment of the force-frequency relationship occurs long before the development of irreversible damage in the myocardium and may be the first sign of the pathological action of cardiotoxins.
Subject(s)
Cobra Cardiotoxin Proteins/pharmacology , Heart/drug effects , Heart/physiology , Myocardial Contraction/drug effects , Naja naja , Animals , Dose-Response Relationship, Drug , RatsABSTRACT
Three-finger snake neurotoxins are selective antagonists of some nicotinic acetylcholine receptor subtypes and are widely used to study these receptors. The peptide neurotoxin azemiopsin, recently isolated from the venom of Azemipos feae, is a selective blocker of muscle-type nicotinic acetylcholine receptor. In order to reduce their toxicity and increase resistance under physiological conditions, we have encapsulated these toxins into nanomaterials. The study of nanomaterials after interaction with neurotoxins by the methods of transmission electron microscopy and dynamic light scattering revealed an increase in the size of nanoparticles, which indicates the inclusion of neurotoxins in nanomaterials.
Subject(s)
Drug Carriers/chemistry , Nanoparticles/chemistry , Neurotoxins/chemistry , Nicotinic Antagonists/chemistry , Polysaccharides/chemistry , Receptors, Nicotinic/metabolism , Sulfates/chemistry , Capsules , Neurotoxins/toxicity , Nicotinic Antagonists/toxicity , Particle Size , Snake Venoms/chemistryABSTRACT
Four dimeric disintegrins were isolated from the venom of the steppe viper V. ursinii using liquid chromatography. Disintegrins prevented adhesion of MCF7 cells to fibronectin, which indicates their interaction with integrin receptors of the αVß1 type. According to mass spectrometry data, the molar masses of disintegrins are about 14 kDa. The method of peptide mapping established the structure of a new heterodimeric disintegrin weighing 13 995.5 Da and shows that it belongs to the class of RGD/KGD-containing disintegrins.
Subject(s)
Disintegrins/chemistry , Protein Multimerization , Reptilian Proteins/chemistry , Viper Venoms/chemistry , Viperidae , Animals , Disintegrins/pharmacology , Humans , MCF-7 Cells , Receptors, Vitronectin/metabolism , Reptilian Proteins/pharmacology , Viper Venoms/pharmacologyABSTRACT
Genes encoding two three-finger toxins TFT-AF and TFT-VN, nucleotide sequences of which were earlier determined by cloning cDNA from venom glands of vipers Azemiops feae and Vipera nikolskii, respectively, were expressed for the first time in E. coli cells. The biological activity of these toxins was studied by electrophysiological techniques, calcium imaging, and radioligand analysis. It was shown for the first time that viper three-finger toxins are antagonists of nicotinic acetylcholine receptors of neuronal and muscle type.
Subject(s)
Muscles/metabolism , Neurons/metabolism , Receptors, Nicotinic/metabolism , Recombinant Proteins/metabolism , Toxins, Biological/metabolism , Viperidae/genetics , Animals , Calcium Signaling , Cell Line, Tumor , Humans , Muscles/cytology , Neurons/cytology , Recombinant Proteins/genetics , Toxins, Biological/geneticsABSTRACT
Compounds activating γ-aminobutyric acid type A receptor were isolated from the toad Bufo bufo venom as a result of chromatographic separation. Analysis of the structure of these compounds by mass spectrometry and nuclear magnetic resonance showed that they are arginine derivatives of dicarboxylic acids and represent suberylarginine, pimeloylarginine, and adipoylarginine.
Subject(s)
Arginine/chemistry , Bufo bufo , Dicarboxylic Acids/chemistry , Dicarboxylic Acids/pharmacology , GABA-A Receptor Agonists/chemistry , GABA-A Receptor Agonists/pharmacology , Parotid Gland/metabolism , Receptors, GABA-A/metabolism , Animals , Dicarboxylic Acids/metabolism , GABA-A Receptor Agonists/metabolism , HEK293 Cells , Humans , LigandsABSTRACT
Fluorescent derivatives are widely used to study the structure and functions of proteins. Quantum dots (QDs), fluorescent semiconductor nanocrystals, have a high quantum yield and are much more resistant to bleaching compared to organic dyes. Conjugates of α-neurotoxins with QDs were used for visualization of human α7 acetylcholine receptors heterologously expressed in GH4C1 pituitary adenoma cells. Specific staining of cells by the conjugated toxins was observed.
Subject(s)
Neurotoxins/chemistry , Neurotoxins/metabolism , Quantum Dots/chemistry , Snake Venoms/chemistry , alpha7 Nicotinic Acetylcholine Receptor/metabolism , Cell Line, Tumor , Humans , Molecular ImagingABSTRACT
Two low-molecular-weight compounds were isolated from the parotid gland secret of the toad Bufo bufo, which by absorption spectra and HPLC-MS/MS chromatography data correspond to di- and trimethyl derivatives of serotonin (5-hydorxytryptamine): bufotenine (confirmed by counter synthesis) and bufotenidine (5-HTQ). In experiments on competitive radioligand binding, these compounds showed a higher affinity and selectivity for neuronal α7 nicotinic acetylcholine receptors compared with the muscular cholinergic receptors. The most efficient compound in terms of binding value was bufotenine, the efficiency of 5-HTQ was an order of magnitude lower, and the minimal activity was exhibited by serotonin.
Subject(s)
Amphibian Venoms/pharmacology , Serotonin/analogs & derivatives , alpha7 Nicotinic Acetylcholine Receptor/metabolism , Amphibian Venoms/chemistry , Animals , Bufo bufo , Cell Line , Ligands , Protein Binding , Rats , alpha7 Nicotinic Acetylcholine Receptor/drug effectsABSTRACT
A new three-finger toxin nakoroxin was isolated from the cobra Naja kaouthia venom, and its complete amino acid sequence was established. Nakoroxin belongs to the group of "orphan" toxins, data on the biological activity of which are practically absent. Nakoroxin shows no cytotoxicity and does not inhibit the binding of α-bungarotoxin to nicotinic acetylcholine receptors of muscle and α7 types. However, it potentiates the binding of α-bungarotoxin to the acetylcholine-binding protein from Lymnaea stagnalis. This is the first toxin with such an unusual property.
Subject(s)
Elapid Venoms/chemistry , Toxins, Biological/chemistry , Toxins, Biological/isolation & purification , Amino Acid Sequence , Toxins, Biological/metabolismABSTRACT
Low-molecular-weight compounds with anticoagulant activity were isolated from the scorpion Heterometrus laoticus venom. The determination of the structure of the isolated compounds by nuclear magnetic resonance and mass spectrometry showed that one of the isolated compounds is adenosine, and the other two are dipeptides leucyl-tryptophan and isoleucyl-tryptophan. The anticoagulant properties of adenosine, which is an inhibitor of platelet aggregation, is well known, but its presence in scorpion venom is shown for the first time. The ability of leucyl-tryptophan and isoleucyl-tryptophan to slow down blood clotting and their presence in scorpion venom are also established for the first time.
Subject(s)
Anticoagulants/chemistry , Anticoagulants/pharmacology , Scorpion Venoms/chemistry , Scorpions , Animals , Mice , Molecular WeightABSTRACT
With the use of surface plasmon resonance (SPR) it was shown that ws-Lynx1, a water-soluble analog of the three-finger membrane-bound protein Lynx1, that modulates the activity of brain nicotinic acetylcholine receptors (nAChRs), interacts with the acetylcholine-binding protein (AChBP) with high affinity, K D = 62 nM. This result agrees with the earlier demonstrated competition of ws-Lynx1 with radioiodinated α-bungarotoxin for binding to AChBP. For the first time it was shown that ws-Lynx1 binds to GLIC, prokaryotic Cys-loop receptor (K D = 1.3 µM). On the contrary, SPR revealed that α-cobratoxin, a three-finger protein from cobra venom, does not bind to GLIC. Obtained results indicate that SPR is a promising method for analysis of topography of ws-Lynx1 binding sites using its mutants and those of AChBP and GLIC.
Subject(s)
Bacterial Proteins/metabolism , Brain/metabolism , Cobra Neurotoxin Proteins/metabolism , Cysteine Loop Ligand-Gated Ion Channel Receptors/metabolism , Membrane Glycoproteins/metabolism , alpha7 Nicotinic Acetylcholine Receptor/metabolism , Animals , Aplysia , Bacterial Proteins/chemistry , Binding Sites , Cell Line , Cell Line, Tumor , Cyanobacteria , Cysteine Loop Ligand-Gated Ion Channel Receptors/chemistry , Drosophila melanogaster , Elapid Venoms/chemistry , Elapid Venoms/metabolism , Elapidae , Escherichia coli , HEK293 Cells , Humans , Membrane Glycoproteins/chemistry , Membrane Glycoproteins/genetics , Models, Molecular , Protein Structure, Secondary , Surface Plasmon Resonance , alpha7 Nicotinic Acetylcholine Receptor/chemistryABSTRACT
Cobra venom factor (CVF) depletes the complement system of the blood by forming stable convertase C3/C5 of the alternative pathway. We found that CVF from the Thailand cobra venom slows down the growth of subcutaneous Ehrlich carcinoma (EC) in mice at a dose of 1.7 nmol/g. Previously, we described a similar effect for the nerve growth factor (NGF) from the venom of this cobra. However, these factors did not exhibit either synergy or additive effect. On the contrary, they neutralized the antitumor effect of each other when they were administered simultaneously. Therefore, on the one hand, the NGF antitumor effect against EC manifests itself under the conditions of inflammation, and normal functioning of the complement system is necessary for this effect to occur. On the other hand, suppression of the humoral immune system leads to a slowdown of the EC growth, but administration of NGF prevents this.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Body Weight/drug effects , Carcinoma, Ehrlich Tumor/drug therapy , Carcinoma, Ehrlich Tumor/pathology , Elapid Venoms/administration & dosage , Nerve Growth Factor/administration & dosage , Animals , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Complement Inactivating Agents/administration & dosage , Dose-Response Relationship, Drug , Mice , Mice, Inbred C57BL , Treatment Outcome , Tumor Burden/drug effectsABSTRACT
Multiple injections of conotoxin MII, a blocker of alfa3-ß2 and alfa6-containing subtypes of nicotinic acetylcholine receptors (n-AChRs), as well as conotoxin ArIB11L16D, a blocker of alfa7 subtype n-AChR, at a dose of 1 nmol/kg reduce both the lactate dehydrogenase level in tumor cells and the inflammatory leukocyte infiltration in tumor tissue in mice bearing Ehrlich carcinoma. The first stage of pathomorphism was detected in the tumor tissue after the treatment with the ArIB11L16D conotoxin, whereas the second stage was observed after the treatment with conotoxins RgIA and MII. Only MII injections led to a significant reduction in tumor growth. Our results show the involvement of n-AChRs in the regulation of metabolic processes and cell-cell interactions related to carcinogenesis and tumor-associated inflammation.
Subject(s)
Carcinogenesis/drug effects , Carcinoma, Ehrlich Tumor/metabolism , Carcinoma, Ehrlich Tumor/pathology , Conotoxins/pharmacology , Nicotinic Antagonists/pharmacology , Receptors, Nicotinic/metabolism , Animals , Carcinoma, Ehrlich Tumor/complications , Inflammation/complications , Inflammation/metabolism , MiceABSTRACT
Nonconventional three-finger toxin BMLCL was isolated from B. multicinctus venom, and its interaction with different subtypes of nicotinic acetylcholine receptor (nAChR) was studied. It was found that BMLCL is able to interact with high efficiency with both α7 and muscle type nAChRs.