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Resumo Venenos sao uma substancia tóxica (composta por uma ou mais toxinas) que podem causando lesao fisiológica dependente da dose. As toxinas sao moléculas bioativas formadas principalmente por compostos enzimáticos e nao enzimático que porque provocam consequéncias indesejáveis nas presas, além disso, exibem atividades biológicas únicas, diversas e específicas que perturbam os processos fisiológicos normais. Entretanto, muitas toxinas, de diferentes animais, tém sido isoladas e muitas delas sao consideradas ótimas ferramentas para pesquisa básica e alvos terapéuticos. Foi relatado que o estresse oxidativo desempenha um papel fundamental na patogénese de várias doengas, como distúrbios neurodegenerativos, distúrbios cardiovasculares e cáncer. O mecanismo pelo qual as toxinas animais atuam nos parametros de estresse oxidativo em várias doengas, ainda nao está estabelecido. O foco principal desta revisao é destacar os principais estudos com toxinas animais como ferramenta terapéutica em diversas doengas, atuando no balango redox do organismo.

Abstract Venoms are a toxic substance (comprised of one or more toxins) that can cause dose-dependent physiological injury. Toxins are bioactive molecules formed primarily by enzymatic and non-enzymatic compounds that cause undesirable conse-quences in prey, in addition, exhibit unique, diverse and specific biological activities that disrupt normal physiological processes. However, many toxins, from different animals, have been isolated and many of them are considered great tools for basic research and therapeutic targets. Oxidative stress has been reported to play a key role in the pathogenesis of various diseases such as neurodegenerative disorders, cardiovascular disorders and cancer. How animal toxins act on oxidative stress parameters in several diseases is not yet established. The main focus of this review is to highlight the main studies with animal toxins as a therapeutic tool in several diseases, acting on the organism's redox balance.

Resumen Los venenos son sustancias tóxicas (compuestas por una o más toxinas) que pueden causar daño fisiológico dependiente de la dosis. Las toxinas son moléculas bioactivas formadas principalmente por compuestos enzimáticos y no enzimáticos que debido a que causan consecuencias indeseables en las presas, además, exhiben actividades biológicas únicas, diversas y específicas que alteran los procesos fisiológicos normales. Sin embargo, se han aislado muchas toxinas de diferentes animales, y muchos de ellos se consideran grandes herramientas para la investigación básica y dianas terapéuticas. Se ha informado que el estrés oxidativo juega un papel clave en la patogenia de diversas enfermedades, como los trastornos neurodegenerativos, enfermedades cardiovasculares y cáncer. El mecanismo por el cual las toxinas animales actúan sobre los parámetros de estrés oxidativo en vários enfermedades, aún no está establecido. El enfoque principal de esta revisión es resaltar los principales estudios con toxinas animales como herramienta terapéutica en diversas enfermedades, actuando en el equilibrio redox del organismo.

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Background:Between 40,000-70,000 people die yearly of rabies, an incurable disease. Besides post-bite vaccination, no treatment is available for it.Methods:First, virus dilution for antiviral effects in mice was determined. Then, animals were treated as follows: control (NaCl 250 µL/animal/day); bufotenine (0.63, 1.05 and 2.1 mg in 250 µL of NaCl/animal/day); rabies (10-6,82CVS dilution); and test (10-6,82 CVS dilution and bufotenine, in the above-mentioned doses). Animals were observed daily for 21 days or until the 3rd stage of rabies infection. Twitch-tension and liposome studies were applied to understand the possible interaction of bufotenine with receptors, particularly acetylcholine.Results:Bufotenine was able to increase the survival rate of intracerebrally virus-infected mice from 15 to 40%. Bufotenine did not seem to interfere with the acetylcholine response in the skeletal muscle, indicating that its mechanism of action is not blocking the virus entrance due to nAChR antagonism. By analyzing liposomes, we could observe that bufotenine did not passively penetrates cell membranes, indicating the necessity of complementary structures to cell penetration.Conclusions:Bufotenine is a promising candidate for drug development. After further chemical modification, it might be possible to dissociate minor side effects, increase efficiency, efficacy and pharmacokinetics, yielding a true anti-rabies drug.(AU)

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Screening for new bioactive peptides in South American anurans has been pioneered in frogs of the genus Phyllomedusa. All frogs of this genus have venomous skin secretions, i.e., a complex mixture of bioactive peptides against potential predators and pathogens that presumably evolved in a scenario of predator-prey interaction and defense against microbial invasion. For every new anuran species studied new peptides are found, with homologies to hormones, neurotransmitters, antimicrobials, and several other peptides with unknown biological activity. From Vittorio Erspamer findings, this genus has been reported as a "treasure store" of bioactive peptides, and several groups focus their research on these species. From 1966 to 2009, more than 200 peptide sequences from different Phyllomedusa species were deposited in UniProt and other databases. During the last decade, the emergence of high-throughput molecular technologies involving de novo peptide sequencing via tandem mass spectrometry, cDNA cloning, pharmacological screening, and surface plasmon resonance applied to peptide discovery, led to fast structural data acquisition and the generation of peptide molecular libraries. Research groups on bioactive peptides in Brazil using these new technologies, accounted for the exponential increase of new molecules described in the last decade, much higher than in any previous decades. Recently, these secretions were also reported as a rich source of multiple antimicrobial peptides effective against multidrug resistant strains of bacteria, fungi, protozoa, and virus, providing instructive lessons for the development of new and more efficient nanotechnological-based therapies for infectious diseases treatment. Therefore, novel drugs arising from the identification and analysis of bioactive peptides from South American anuran biodiversity have a promising future role on nanobiotechnology.

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Accidents involving toad poisoning are frequent and dogs are the most common victims; they become poisoned by biting or ingesting a toad. When released in the organism, the venom is absorbed by both the oral mucosa and the digestive tract, initiating its toxic action. The aim of this work was to evaluate the clinical and electrocardiographic aspects of dogs subjected to experimental toad poisoning, as well as their response to treatment with propranolol. Twenty dogs were divided into two groups, a control group (n = 5) and a poisoned group (n = 15). After general anesthesia, the control group received a placebo, while the poisoned group received a venom aliquot through an orogastric tube. Results were tested through multivariate analysis (p < 0.05). The animals in the poisoned group had gastrointestinal symptoms including emesis, intense salivation, hyperemic or congested oral mucosa and pasty diarrhea. Non-responsive mydriasis, nystagmus, depression, stupor, tachypnea, opisthotonus and ataxia were also manifested by 100 percent of the poisoned animals. Affected dogs had an increase in blood pressure, statistically significant throughout study. Five poisoned animals developed ventricular tachycardia and were treated with propranolol (0.5 mg/kg IV). All propranolol-treated animals returned to normal sinus rhythm, which evidences the efficacy of this drug to treat ventricular arrhythmias caused by toad venom.(AU)

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