Experimental Lachesis muta rhombeata envenomation and effects of soursop (Annona muricata) as natural antivenom

Abstract\ud \ud Background\ud In the Atlantic forest of the North and Northeast regions of Brazil, local population often uses the fruit juice and the aqueous extract of leaves of soursop (Annona muricata L.) to treat Lachesis muta rhombeata envenomation. Envenomation is a relevant health issue in these areas, especially due to its severity and because the production and distribution of antivenom is limited in these regions. The aim of the present study was to evaluate the relevance of the use of soursop leaf extract and its juice against envenomation by Lachesis muta rhombeata.\ud \ud \ud Methods\ud We evaluated the biochemical, hematological and hemostatic parameters, the blood pressure, the inflammation process and the lethality induced by Lachesis muta rhombeata snake venom. We also assessed the action of the aqueous extract of leaves (AmL) and juice (AmJ) from A. muricata on the animal organism injected with L. m. rhombeata venom (LmrV) in the laboratory environment.\ud \ud \ud Results\ud LmrV induced a decrease of total protein, albumin and glucose; and increase of creatine kinase, aspartate aminotransferase, and urea concentrations. It provoked hemoconcentration followed by reduction of hematocrit, an increase in prothrombin time and partial thromboplastin time and a decrease of the blood pressure. LmrV induced the release of interleukin-6, an increase in neutrophils and changes in the serum protein profile, characteristic of the acute inflammatory process. LD50 values were similar for the groups injected with LmrV and treated or untreated with AmJ and AmL. Both treatments play a role on the maintenance of blood glucose, urea and coagulation parameters and exert a protective action against the myotoxicity. However, they seem to worsen the hypotension caused by LmrV.\ud \ud \ud Conclusion\ud The treatments with AmJ and AmL present some beneficial actions, but they might intensify some effects of the venom. Therefore, additional studies on A. muricata are necessary to enable its use as natural antivenom for bushmaster snakebite.The authors are grateful to Dr. Marcelo Dias Baruffi, Luisa Helena Dias Costa,\ud Luciana Prado Turin, and Laboratory of Clinical Analysis of School of\ud Pharmaceutical Sciences of Ribeirão Preto for assistance in clinical analysis. This\ud study was supported by the following grants: the São Paulo Research\ud Foundation (FAPESP, grant no. 2005/54855–0 and doctoral scholarship to FAC\ud 2012/13590–8), the National Council for Scientific and Technological\ud Development (CNPq, masters scholarship to CMC 143472/2011–9) and\ud Research Support Center in Animal Toxins (NAP-TOXAN-USP, grant no. 12-\ud 125432.1.3). Thanks are also due to the Center for the Study of Venoms and\ud Venomous Animals (CEVAP) of UNESP for enabling the publication of this paper\ud (CAPES, grant no\ud . 23038.006285/2011–21, AUXPE – Toxinologia – 1219/2011)

ADDovenom: Thermostable Protein-Based ADDomer Nanoparticles as New Therapeutics for Snakebite Envenoming

Snakebite envenoming can be a life-threatening medical emergency that requires prompt medical intervention to neutralise the effects of venom toxins. Each year up to 138,000 people die from snakebites and threefold more victims suffer life-altering disabilities. The current treatment of snakebite relies solely on antivenom—polyclonal antibodies isolated from the plasma of hyperimmunised animals—which is associated with numerous deficiencies. The ADDovenom project seeks to deliver a novel snakebite therapy, through the use of an innovative protein-based scaffold as a next-generation antivenom. The ADDomer is a megadalton-sized, thermostable synthetic nanoparticle derived from the adenovirus penton base protein; it has 60 high-avidity binding sites to neutralise venom toxins. Here, we outline our experimental strategies to achieve this goal using state-of-the-art protein engineering, expression technology and mass spectrometry, as well as in vitro and in vivo venom neutralisation assays. We anticipate that the approaches described here will produce antivenom with unparalleled efficacy, safety and affordability

Caracterização estrutural e bioquímica da enzima fumarato hidratase classe II de Schistosoma mansoni

Schistomiasis is a neglected tropical disease caused by trematodes worms from the genus Schistosoma. Schistosomiasis is the second most devastating parasitic disease after malaria. The disease has a high economic burden and affects mainly poor population without access to proper sanitation. Praziquantel is the only drug approved for the treatment of schistosomiasis and resistance is already reported. Fumarate hydratases or fumarases are enzymes that catalyze the reversible hydration of fumarate to L-malate. This enzyme participates in DNA repair and important metabolic processes such as the urea and the tricarboxylic acid cycles. Fumarases are divided in two classes, and Schistosoma mansoni possess both, being class I localized in mitochondria, while class II is cytosolic. The fundamental role of fumarases in the metabolism make them potential target for drug design against schistosomiasis. This work describes, for the first time, the cloning, expression and purification protocol for the class II fumarate hydratase from Schistosoma mansoni (SmFHII). In order to estimate the contribution of the reverse reaction, the enzyme was kinetically characterized using both substrates concomitantly. SmFHII was shown to follow a MichaelisMenten mechanism of catalysis with of 19 mM-1s-1 and of 49 mM-1s-1, and of 0.56 mM and of 0.15 mM. Differential scanning fluorimetry (DSF) performed under different chemical environments shows that the highest thermal stability is reached at pH 7.5 and at higher ionic strength. The significant thermoshift observed for SmFHII in presence of well known ligands makes DSF the adequate technique for ligand screening. SmFHII structure in complex with L-malate was determined by single crystal X-ray diffraction, at 1.85 Å resolution. A new construct [SmFHII(Δ263-277)] lacking the additional portion only found in trematode worms was also evaluated by kinetic and DSF experiments. Although not essential for activity, the results suggest that the removal of this region impacts on protein stability and may has influence on L-malate catalysis. The differences between SmFHII and human fumarase are distributed all over the structure, and could be explored to design new selective inhibitors.A esquistossomose é uma doença tropical negligenciada causada por parasitas trematódeos do gênero Schistosoma. A esquistossomose é a segunda doença parasitária mais devastadora do mundo, atrás apenas da malária. A doença tem um alto impacto econômico, afetando principalmente a população pobre sem acesso a saneamento adequado. Praziquantel é o único medicamento aprovado para o tratamento da esquistossomose e já existem relatos de parasitas resistentes a esse fármaco. Fumarato hidratases ou fumarases são enzimas que catalisam a hidratação reversível de fumarato em L-malato. Essa enzima participa do reparo ao dano do DNA e de processos metabólicos importantes, como os ciclos da uréia e do ácido tricarboxílico. As fumarases são divididas em duas classes e o S. mansoni possui ambas, sendo a classe I mitocondrial, enquanto a classe II é citosólica. O papel fundamental da fumarase no metabolismo faz dela um alvo potencial para o planejamento de fármacos contra a esquistossomose. Este trabalho descreve, pela primeira vez, o protocolo de clonagem, expressão e purificação da fumarato hidratase classe II de Schistosoma mansoni (SmFHII). De forma a estimar a contribuição da reação reversa, a enzima foi caracterizada cineticamente utilizando os dois substratos concomitantemente. A SmFHII demonstrou seguir o mecanismo de catálise de Michaelis-Menten, tendo um de 19 mM-1s-1 e de 49 mM-1s-1, e de 0,56 mM e de 0,15 mM. Fluorimetria de varredura diferencial (DSF) realizada em diferentes ambientes químicos demonstrou que a maior estabilidade térmica da proteína é alcançada em pH 7,5 e também com o aumento alta força iônica, além de ser uma técnica útil para a triagem de ligantes. A estrutura da SmFHII foi determinada por difração de raios-X de monocristal, com uma resolução de 1,85 Å. Uma nova construção [SmFHII(Δ263-277)] sem a porção adicional, encontrada apenas em vermes de trematódeos, também foi avaliada por ensaios cinéticos e de DSF. Embora não seja essencial para a atividade enzimática, os resultados sugerem que a remoção dessa região afeta a estabilidade da proteína e pode ter influência na catálise do L-malato. As diferenças entre SmFHII e fumarase humana estão distribuídas por toda a estrutura e podem ser exploradas para delinear novos inibidores seletivos

Tityus serrulatus envenoming in non-obese diabetic mice: a risk factor for severity

Abstract Background In Brazil, accidents with venomous animals are considered a public health problem. Tityus serrulatus (Ts), popularly known as the yellow scorpion, is most frequently responsible for the severe accidents in the country. Ts envenoming can cause several signs and symptoms classified according to their clinical manifestations as mild, moderate or severe. Furthermore, the victims usually present biochemical alterations, including hyperglycemia. Nevertheless, Ts envenoming and its induced hyperglycemia were never studied or documented in a patient with diabetes mellitus (DM). Therefore, this is the first study to evaluate the glycemia during Ts envenoming using a diabetic animal model (NOD, non-obese diabetic). Methods Female mice (BALB/c or NOD) were challenged with a non-lethal dose of Ts venom. Blood glucose level was measured (tail blood using a glucose meter) over a 24-h period. The total glycosylated hemoglobin (HbA1c) levels were measured 30 days after Ts venom injection. Moreover, the insulin levels were analyzed at the glycemia peak. Results The results demonstrated that the envenomed NOD animals presented a significant increase of glycemia, glycosylated hemoglobin (HbA1c) and insulin levels compared to the envenomed BALB/c control group, corroborating that DM victims present great risk of developing severe envenoming. Moreover, the envenomed NOD animals presented highest risk of death and sequelae. Conclusions This study demonstrated that the diabetic victims stung by Ts scorpion should be always considered a risk group for scorpion envenoming severity

Heterologous expression of Ts8, a neurotoxin from Tityus serrulatus venom, evidences its antifungal activity.

peer reviewedIn this study we expressed the Ts8, a neurotoxin from Tityus serrulatus scorpion venom, in Pichia pastoris yeast. We evaluated the peptide expression in different conditions, such as pH, temperature, and addition of casamino acids supplement. Analyses of expressed products by mass spectrometry and Edman degradation showed that rTs8 has sites that allow its cleavage by yeast proteases released into the culture medium. The casamino acids addition was favourable for toxin expression, however, was not sufficient to minimize proteolytic degradation. Functional assays with recombinant toxin fragments and native toxins have demonstrated the release of cytokines such as TNF-α and IL-1β in some peptides tested. In addition, the toxins were shown to inhibit the Pichia pastoris growth in antifungal test and were not toxic to alveolar macrophages cells at the concentrations analyzed The electrophysiological screening, by voltage clamp technique, showed that the rTs8 fragment with the highest molecular weight inhibited the Kv1.3 channel, whereas the N-terminal fragment had no activity on the ion channels tested

Cell migration inhibition activity of a non-RGD disintegrin from Crotalus durissus collilineatus venom

Abstract Background In recent decades, snake venom disintegrins have received special attention due to their potential use in anticancer therapy. Disintegrins are small and cysteine-rich proteins present in snake venoms and can interact with specific integrins to inhibit their activities in cell-cell and cell-ECM interactions. These molecules, known to inhibit platelet aggregation, are also capable of interacting with certain cancer-related integrins, and may interfere in important processes involved in carcinogenesis. Therefore, disintegrin from Crotalus durissus collilineatus venom was isolated, structurally characterized and evaluated for its toxicity and ability to interfere with cell proliferation and migration in MDA-MB-231, a human breast cancer cell line. Methods Based on previous studies, disintegrin was isolated by FPLC, through two chromatographic steps, both on reversed phase C-18 columns. The isolated disintegrin was structurally characterized by Tris-Tricine-SDS-PAGE, mass spectrometry and N-terminal sequencing. For the functional assays, MTT and wound-healing assays were performed in order to investigate cytotoxicity and effect on cell migration in vitro, respectively. Results Disintegrin presented a molecular mass of 7287.4 Da and its amino acid sequence shared similarity with the disintegrin domain of P-II metalloproteases. Using functional assays, the disintegrin showed low cytotoxicity (15% and 17%, at 3 and 6 μg/mL, respectively) after 24 h of incubation and in the wound-healing assay, the disintegrin (3 μg/mL) was able to significantly inhibit cell migration (24%, p < 0.05), compared to negative control. Conclusion Thus, our results demonstrate that non-RGD disintegrin from C. d. collilineatus induces low cytotoxicity and inhibits migration of human breast cancer cells. Therefore, it may be a very useful molecular tool for understanding ECM-cell interaction cancer-related mechanisms involved in an important integrin family that highlights molecular aspects of tumorigenesis. Also, non-RGD disintegrin has potential to serve as an agent in anticancer therapy or adjuvant component combined with other anticancer drugs

Unraveling the structure and function of <i>Cdc</i>PDE: A novel phosphodiesterase from <i>Crotalus durissus collilineatus</i> snake venom

This study reports the isolation, structural, biochemical, and functional characterization of a novel phosphodiesterase from Crotalus durissus collilineatus venom (CdcPDE). CdcPDE was successfully isolated from whole venom using three chromatographic steps and represented 0.7% of total protein content. CdcPDE was inhibited by EDTA and reducing agents, demonstrating that metal ions and disulfide bonds are necessary for its enzymatic activity. The highest enzymatic activity was observed at pH 8-8.5 and 37 °C. Kinetic parameters indicated a higher affinity for the substrate bis(p-nitrophenyl) phosphate compared to others snake venom PDEs. Its structural characterization was done by the determination of the protein primary sequence by Edman degradation and mass spectrometry, and completed by the building of molecular and docking-based models. Functional in vitro assays showed that CdcPDE is capable of inhibiting platelet aggregation induced by adenosine diphosphate in a dose-dependent manner and demonstrated that CdcPDE is cytotoxic to human keratinocytes. CdcPDE was recognized by the crotalid antivenom produced by the Instituto Butantan. These findings demonstrate that the study of snake venom toxins can reveal new molecules that may be relevant in cases of snakebite envenoming, and that can be used as molecular tools to study pathophysiological processes due to their specific biological activities

ADDovenom : Thermostable Protein-Based ADDomer Nanoparticles as New Therapeutics for Snakebite Envenoming

Snakebite envenoming can be a life-threatening medical emergency that requires prompt medical intervention to neutralise the effects of venom toxins. Each year up to 138,000 people die from snakebites and threefold more victims suffer life-altering disabilities. The current treatment of snakebite relies solely on antivenom—polyclonal antibodies isolated from the plasma of hyperimmunised animals—which is associated with numerous deficiencies. The ADDovenom project seeks to deliver a novel snakebite therapy, through the use of an innovative protein-based scaffold as a next-generation antivenom. The ADDomer is a megadalton-sized, thermostable synthetic nanoparticle derived from the adenovirus penton base protein; it has 60 high-avidity binding sites to neutralise venom toxins. Here, we outline our experimental strategies to achieve this goal using state-of-the-art protein engineering, expression technology and mass spectrometry, as well as in vitro and in vivo venom neutralisation assays. We anticipate that the approaches described here will produce antivenom with unparalleled efficacy, safety and affordability