Cytotoxic effects of crotoxin from Crotalus durissus terrificus snake in canine mammary tumor cell lines

Background: Mammary gland tumors are the most prevalent neoplasm in intact female dogs, and they are good natural models to study comparative oncology. Most canine mammary malignancies, as in women, are commonly refractory to conventional therapies and demand continuous new therapeutic approaches. Crotalus durissus terrificus, also called rattlesnake, has more than 60 different proteins in its venom with multiple pharmaceutical uses, such as antitumor, antiviral, and antimicrobial action. Crotoxin, a potent β-neurotoxin formed by the junction of two subunits, a basic subunit (CB-PLA2) and an acidic subunit (crotapotin), has already been reported to have anticancer properties in different types of cancers. Methods: In this work, we describe the cytotoxic potential of crotoxin and its subunits compared to doxorubicin (drug of choice) in two canine mammary carcinoma cell lines. Results: Crotoxin, CB-PLA2, crotalic venom, and doxorubicin decreased cell viability and the ability to migrate in a dose-dependent manner, and crotapotin did not present an antitumoral effect. For all compounds, the predominant cell death mechanism was apoptosis. In addition, crotoxin did not show toxicity in normal canine mammary gland cells. Conclusion: Therefore, this work showed that crotoxin and CB-PLA2 had cytotoxic activity, migration inhibition, and pro-apoptotic potential in canine mammary gland carcinoma cell lines, making their possible use in cancer research.

Antileishmanial effects of γCdcPLI, a phospholipase A2 inhibitor from Crotalus durissus collilineatus snake serum, on Leishmania (Leishmania) amazonensis

BACKGROUND Leishmaniasis, a neglected disease caused by the parasite Leishmania, is treated with drugs associated with high toxicity and limited efficacy, in addition to constant reports of the emergence of resistant parasites. In this context, snake serums emerge as good candidates since they are natural sources with the potential to yield novel drugs. OBJECTIVES We aimed to show the antileishmanial effects of γCdcPLI, a phospholipase A2 inhibitor from Crotalus durissus collilineatus snake serum, against Leishmania (Leishmania) amazonensis. METHODS Promastigotes forms were exposed to γCdcPLI, and we assessed the parasite viability and cell cycle, as well as invasion and proliferation assays. FINDINGS Despite the low cytotoxicity effect on macrophages, our data indicate that γCdcPLI has a direct effect on parasites promoting an arrest in the G1 phase and reduction in the G2/M phase at the highest dose tested. Moreover, this PLA2 inhibitor reduced the parasite infectivity when promastigotes were pre-treated. Also, we demonstrated that the γCdcPLI treatment modulated the host cell environment impairing early and late steps of the parasitism. MAIN CONCLUSIONS γCdcPLI is an interesting tool for the discovery of new essential targets on the parasite, as well as an alternative compound to improve the effectiveness of the leishmaniasis treatment.

Oxidative stress and changes in hematological and biochemical biomarkers in Crotalus durissus terrificus (South American rattlesnake) venom-induced acute kidney injury in rats / Estrés oxidativo y alteraciones en biomarcadores hematológicos y bioquímicos en lesión renal aguda inducida por el veneno de Crotalus durissus terrificus (cascabel de America del Sur) en ratones

Abstract Acute kidney injury (AKI) is the major cause of mortality following bites by the South American rattlesnake Crotalus durissus terrificus. We investigated the early onset of Crotalus durissus terrificus venom-induced AKI in rats within 2 h of venom injection and its attenuation by antivenom. Several biomarkers were used to monitor AKI in the absence or presence of antivenom. Male Wistar rats were divided into five groups (n=5 each): G1, rats injected with saline (control); G2, rats injected with venom (6 mg kg-1, intraperitoneally) and euthanized after 2 h to evaluate AKI; G3 and G4, rats injected with 0.9% sterile saline or antivenom 2 h after venom, respectively, and monitored until death or up to 24 h post-venom, and G5, rats injected with antivenom alone and monitored for 24 h. Blood, urine and renal tissue samples were collected immediately after death to assess oxidative stress, hematological and biochemical alterations, and renal histological damage. Venom caused AKI within 2 h (G2) that persisted for up to 8.2 ± 1.6 h (G3), as confirmed by increases in blood urea, creatinine, and renal proteinuria; these increases were attenuated by antivenom. There were no changes in blood protein concentrations in G2 and G3, whereas there were increases in blood reduced glutathione, glutathione peroxidase, and plasma TBARS (but not in catalase) that were attenuated to varying extents by antivenom. There were no marked changes in platelets or leukocytes, but an increase in erythrocytes after 8.2 h with venom alone was attenuated by antivenom. Renal glomerular and tubular damage was greatest after 2 h post-venom groups alone was attenuated by antivenom. Renal glomerular and tubular damage was greatest after 2 h post-venom and declined thereafter. Venom caused early-onset AKI, with variable effects on lipid peroxidation and oxidative stress. Antivenom attenuated the AKI, as shown by the decrease in blood urea and the normalization of proteinuria, without protecting against lipid peroxidation.

Resumen La injuria o lesión renal aguda (LRA) es la mayor causa de mortalidad debido a las mordeduras por cascabeles Crotalus durissus terrificus. Se estudió la instalación precoz de LRA, en ratas, inducida por el veneno de Crotalus durissus terrificus después de 2 h de su inoculación y la atenuación por el antiveneno. Se utilizaron diversos biomarcadores para monitorear LRA en ausencia o presencia del antiveneno. Ratas Wistar machos fueron divididos en 5 grupos (n=5 por grupo): G1, ratas inoculadas con solución salina (control); G2, ratas inoculadas con veneno (6 mg kg-1 dosis, vía intraperitoneal), y sacrificadas después de 2 h para evaluar LRA; G3 y G4, ratas inoculadas con 0.9% de solución salina esterilizada o antiveneno luego de 2 h después de inoculado el veneno, respectivamente, y monitoreadas hasta su muerte o hasta 24 h después de inoculado el veneno; y G5, ratas inoculadas con antiveneno solo y monitoreadas durante 24 h. Las muestras de sangre, orina, y tejido renal fueron colectadas inmediatamente después de la muerte de los animales para evaluar estrés oxidativo, alteraciones hematológicas y bioquímicas, y daño histológico renal. El veneno causó LRA dentro de las 2 h (G2) persistiendo durante más de 8,2 ± 1,6 h (G3), estando esto confirmado por el incremento de urea sanguínea, creatinina, y proteinuria renal; estos aumentos disminuyeron con la aplicación del antiveneno. No se observaron alteraciones en las concentraciones de proteínas sanguíneas en G2 y G3, mientras que se encontraron incrementos en glutatión reducido sanguíneo, glutatión peroxidasa y TBARS plasmática (pero no en catalasa), que disminuyeron con la aplicación del antiveneno aunque en diferente grado. No ocurrieron alteraciones marcadas de plaquetas o leucocitos, mientras que el aumento de glóbulos rojos observado luego de 8,2 h de la inoculación con veneno, disminuyó con el antiveneno. El daño renal glomerular y tubular fue más importante luego de 2 h de la inoculación con veneno y posteriormente disminuyó. El veneno causó LRA precoz a las 2 h, con efectos variables sobre la peroxidación lipídica y el estrés oxidativo. El antiveneno redujo el daño renal, conforme lo demostrado por la disminución en la urea sanguínea y por la normalización de la proteinuria, aunque no se observó protección contra la peroxidación lipídica.

Analysis of the protein profile of the venoms of snakes Bothrops asper, Bothrocophias myersi and Crotalus durissus from the Colombian Andean Region obtained by RP-HPLC / Análisis del perfil proteico de los venenos de Bothrops asper, Bothrocophias myersi y Crotalus durissus serpientes de la Región Andina en Colombia obtenidos por RP-HPLC

ABSTRACT Snake venoms comprise a highly complex mixture of proteins, and there is also a high interspecific and intraspecific variability in their composition, even in the same region. Our aim was to compare the composition of the venoms of Bothrocophias myersi, Crotalus durissus, and Bothrops asper, snakes from the Colombian Andean region by Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC). The venoms were given to the research group under an agreement with Fundación Zoológica de Cali. The venoms pool was obtained by manual extraction, lyophilized and frozen. The venom protein was quantified by direct measurement with Nanodrop® 280 nm. The protein composition was established by RP-HPLC, using a Lichosper 100 RP, C18 column (250X4 mm) with a pore size of 5-m, as well as by Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). The highest quantity of protein was found in the venom of B. myersi (108.6 mg/ mL) followed by C. durissus (78.1 mg/mL) and B. asper (74.1 mg/mL). All venoms showed bands of 15 and 50 KDa by using SDS-PAGE. B. myersi venom chromatogram exhibited 16 peaks by RP-HPLC. We conclude that the composition of the three venoms is quite similar, being phospholipase A2 the common protein therein, and together with metalloproteinases they were the most abundant protein families in the venom of B. myersi. SDS-PAGE and RP-HPLC techniques allow a first approach to the profile of the venoms, which in turn could clarify the clinical syndrome produced.

RESUMEN Los venenos de las serpientes comprenden una mezcla compleja de proteínas, y existe una alta variabilidad interespecífica e intra-específica en su composición, incluso en la misma región. Nuestro objetivo fue comparar la composición de los venenos de Bothrocophias myersi, Crotalus durissus y Bothrops asper de la región andina de Colombia, mediante cromatografía líquida de alta eficiencia en fase reversa (RP-HPLC). Los venenos fueron entregados al grupo de investigación mediante un convenio con la Fundación Zoológica de Cali. El pool de venenos fue obtenido por extracción manual, liofilizado y congelado. La proteína de los venenos fue cuantificada por Absorbancia 280nm por medición directa con Nanodrop®. La composición proteica se estableció por RP-HPLC, utilizando una columna Lichosper 100 RP, C18 (250X4 mm) con un tamaño de poro de 5-jm, así como por electroforesis en gel dodecil sulfato de sodio-poliacrilamida (SDS-PAGE). La mayor cantidad de proteínas se encontró en el veneno de B. myersi (108.6 mg/mL), seguido de C. durissus (78.1 mg/mL) y B. asper (74.1 mg/mL). Todos los venenos mostraron bandas de 15 y 50 KDa por SDS-PAGE. El cromatograma de B. myersi exhibió 16 picos por RP-HPLC. Concluimos que la composición de los tres venenos es bastante similar, siendo la fosfolipasa A2 la proteína común en estos y junto con las metaloproteinasas fueron las familias de proteínas más abundantes en el veneno de B. myersi. Las técnicas de SDS-PAGE y el RP-HPLC permiten un primer acercamiento al perfil de los venenos, lo que a su vez podría contribuir a esclarecer el síndrome clínico producido.

Efectos bioquímicos e histopatológicos en ratas inducidos por el veneno de Crotalus durissus cumanensis del municipio Falcón, estado Falcón, Venezuela / Biochemical and Histopathological Effects in rats Induced by the Poison of Crotalus durissus cumanensis from the Falcón Municipality, Falcón State, Venezuela

Resumen El accidente ofídico representa un importante problema de salud pública en las zonas tropicales y subtropicales del mundo. La cascabel común (Crotalus durissus cumanensis) es la serpiente del género Crotalus más abundante en Venezuela. El objetivo fue determinar los cambios séricos en la alanino aminotransferasa (ALT), aspartato aminotransferasa (AST), lactato deshidrogenasa (LDH) y creatina fosfocinasa (CK) en ratas, inducidos por el veneno de Crotalus durissus cumanensis, así como el establecimiento de los efectos histopatológicos. Se prepararon cinco grupos experimentales con tres ratas cada uno, reservando un grupo control placebo (G1), el cual fue tratado por ruta IP con 100 µL de solución salina fisiológica estéril (SSFe). Al resto de los animales se les administraron 50 µg de veneno nativo por la misma vía. Estos fueron sacrificados a las 1 (G2), 3 (G3), 6 (G4) y 9 (G5) horas posinoculación, con tomas de muestras séricas para determinaciones de las referidas enzimas y de diferentes órganos para estudios histopatológicos (corazón, músculo esquelético, hígado y riñón). Se observó un incremento en la ALT (p < 0,005) a partir de la primera hora posinyección, con un pico a la novena hora de 147 ± 8 UI/L; para la AST (p < 0,005) a partir de la primera hora posinyección con concentración pico a la sexta hora (293 ± 8 UI/L). De la LDH (p < 0,005) se registró un pico máximo de 2700 ± 8 UI/L a la novena hora posinyección. La CK (p < 0,005) mostró un pico máximo de concentración a la sexta hora (1489,66 ± 8,5 UI/L). Los resultados histopatológicos en tejido cardíaco mostraron hiperemia, congestión y necrosis de Zenker; en músculo esquelético, hiperemia, infiltrado inflamatorio, necrosis de Zenker; en hígado, extravasación de glóbulos rojos, congestión de sinusoides, telangiectasia e infiltrado inflamatorio en vena centrolobulillar. El riñón mostró hemorragia en túbulos contorneados, infiltrado inflamatorio, colapso de los túbulos hasta la pérdida de la arquitectura del órgano. Los efectos observados fueron tiempo-dependientes. Los resultados pueden indicar un posible efecto miotóxico y hepatotóxico.

Abstract The ophidian accident represents a major public health problem in the tropical and subtropical areas of the world. The common rattlesnake (Crotalus durissus cumanensis) is the most abundant snake of the genus Crotalus in Venezuela. The objective was to determine the serum changes in alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and creatine phosphokinase (CK) in rats, induced by the poison of Crotalus durissus cumanensis, as well as the establishment of histopathological effects. Five experimental groups were prepared with 3 rats each, reserving a placebo control group (G1), which was treated by IP route with 100 µL of sterile Physiological Saline Solution (SSFe), the rest of the animals were administered 50 µg of venom native by the same route, which were sacrificed at 1 (G2), 3 (G3), 6 (G4) and 9 (G5) hours post-inoculation, with serum samples taken for determinations of said enzymes, as well as different orgns for histopathological studies (heart, skeletal muscle, liver and kidney). An increase in ALT (p <0.005) was observed from the first hour post injection, with a peak at the ninth hour of 147 ± 8 IU / L; for AST (p <0.005) from the first hour post-injection with peak concentration at the sixth hour (293 ± 8 IU / L); with respect to LDH (p <0.005), a maximum peak of 2700 ± 8 IU / L was recorded at the ninth hour post-injection. CK (p <0.005) registered a maximum concentration peak at the sixth hour (1489.66 ± 8.5 IU / L). Histopathological results in cardiac tissue showed Zenker hyperemia, congestion, and necrosis; in skeletal muscle hyperemia, inflammatory infiltrate, Zenker's necrosis; in liver extravasation of red blood cells, sinus congestion, telangiectasia and inflammatory infiltrate in the centrilobular vein; the kidney showed hemorrhage in contoured tubules, inflammatory infiltrate, collapse of the tubules until loss of the organ architecture. The observed effects were time-dependent. The results could indicate a possible myotoxic and hepatotoxic effect.

Geographic variation of individual venom profile of Crotalus durissus snakes

South American rattlesnakes are represented in Brazil by a single species, Crotalus durissus, which has public health importance due to the severity of its envenomation and to its wide geographical distribution. The species is subdivided into several subspecies, but the current classification is controversial. In Brazil, the venoms of C. d. terrificus and C. d. collilineatus are used for hyperimmunization of horses for antivenom production, even though the distinction of these two subspecies are mostly by their geographical distribution. In this context, we described a comparative compositional and functional characterization of individual C. d. collilineatus and C. d. terrificus venoms from three Brazilian states. Methods: We compared the compositional patterns of C. d. terrificus and C. d. collilineatus individual venoms by 1-DE and RP-HPLC. For functional analyzes, the enzymatic activities of PLA2, LAAO, and coagulant activity were evaluated. Finally, the immunorecognition of venom toxins by the crotalic antivenom produced at Butantan Institute was evaluated using Western blotting. Results: The protein profile of individual venoms from C. d. collilineatus and C. d. terrificus showed a comparable overall composition, despite some intraspecific variation, especially regarding crotamine and LAAO. Interestingly, HPLC analysis showed a geographic pattern concerning PLA2. In addition, a remarkable intraspecific variation was also observed in PLA2, LAAO and coagulant activities. The immunorecognition pattern of individual venoms from C. d. collilineatus and C. d. terrificus by crotalic antivenom produced at Butantan Institute was similar. Conclusions: The results highlighted the individual variability among the venoms of C. durissus ssp. specimens. Importantly, our data point to a geographical variation of C. durissus ssp. venom profile, regardless of the subspecies, as evidenced by PLA2 isoforms complexity, which may explain the increase in venom neurotoxicity from Northeastern through Southern Brazil reported for the species.(AU)

Local and systemic effects caused by Crotalus durissus terrificus, Crotalus durissus collilineatus, and Crotalus durissus cascavella snake venoms in swiss mice

Abstract INTRODUCTION: Crotalus envenomations cause serious complications and can be fatal without appropriate treatment. Venom isoforms present and inter/intraspecific variations in the venom composition can result in different symptoms presented by bites by snakes from the same species but from different geographical regions. We comparatively evaluated the local and systemic effects caused by Crotalus durissus terrificus (Cdt), C.d. collilineatus (Cdcolli), and C.d. cascavella (Cdcasc) envenomation. METHODS: Venom chromatography was performed. Proteolytic, phospholipase, and LAAO activities were analyzed. Edema, myotoxicity, hepatotoxicity, nephrotoxicity, and coagulation alterations were evaluated. RESULTS: The venom SDS-PAGE analyses found the presence of convulxin, gyroxin, crotoxin, and crotamine in Cdt and Cdcolli venoms. Crotamine was not present in the Cdcasc venom. Cdt, Cdcollli, and Cdcasc venoms had no proteolytic activity. Only Cdcasc and Cdt venoms had phospholipase activity. LAAO activity was observed in Cdcolli and Cdcasc venoms. Cdcolli and Cdcasc venoms caused 36.7% and 13.3% edema increases, respectively. Cdt venom caused a 10% edema induction compared to those by other venoms. All venoms increased TOTAL-CK, MB-CK, and LDH levels (indicating muscle injury) and ALT, AST, GGT, and ALP levels (markers of liver damage) and were able to induce a neuromuscular blockade. Urea and creatinine levels were also altered in both plasma and urine, indicating kidney damage. Only Cdcolli and Cdcasc venoms increased TAPP and TAP. CONCLUSIONS: Together, these results allow us to draw a distinction between local and systemic effects caused by Crotalus subspecies, highlighting the clinical and biochemical effects produced by their respective venoms.

Antivenomic approach of different Crotalus durissus collilineatus venoms

Our group has previously performed a proteomic study verifying that individual variations can occur among Crotalus durissus collilineatus venoms. These variations may lead to differences in venom toxicity and may result in lack of neutralization of some components by antivenom. In this way, this study aimed to evaluate the Brazilian anticrotalic serum capacity in recognizing twenty-two Crotalus durissus collilineatus venoms, as well as their fractions. Methods: The indirect enzyme-linked immunosorbent assay (ELISA) was chosen to evaluate the efficacy of heterologous anticrotalic serum produced by Instituto Butantan (Brazil) in recognizing the twenty-two Crotalus durissus collilineatus venoms and the pool of them. Moreover, the venom pool was fractionated using reversed-phase fast protein liquid chromatography (RP-FPLC) and the obtained fractions were analyzed concerning antivenom recognition. Results: Evaluation of venom variability by ELISA showed that all venom samples were recognized by the Brazilian anticrotalic antivenom. However, some particular venom fractions were poorly recognized. Conclusion: This study demonstrated that the Brazilian anticrotalic serum recognizes all the different twenty-two venoms of C. d. collilineatus and their fractions, although in a quantitatively different way, which may impact the effectiveness of the antivenom therapy. These results confirm the need to use a pool of venoms with the greatest possible variability in the preparation of antivenoms, in order to improve their effectiveness.(AU)

Immunotherapeutic potential of Crotoxin: anti-inflammatory and immunosuppressive properties

For the past 80 years, Crotoxin has become one of the most investigated isolated toxins from snake venoms, partially due to its major role as the main toxic component in the venom of the South American rattlesnake Crotalus durissus terrificus. However, in the past decades, progressive studies have led researchers to shift their focus on Crotoxin, opening novel perspectives and applications as a therapeutic approach. Although this toxin acts on a wide variety of biological events, the modulation of immune responses is considered as one of its most relevant behaviors. Therefore, the present review describes the scientific investigations on the capacity of Crotoxin to modulate anti-inflammatory and immunosuppressive responses, and its application as a medicinal immunopharmacological approach. In addition, this review will also discuss its mechanisms, involving cellular and molecular pathways, capable of improving pathological alterations related to immune-associated disorders.(AU)

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

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-TricineSDS-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.(AU)

Efecto citotóxico de fosfolipasas A2 del veneno de Crotalus durissus cumanensis de Colombia / Cytotoxic effect of A2 phospholipases of the venom of Crotalus durissus cumanensis from Colombia / Efeito citotóxico da fosfolipase A2 do veneno de Crotalus durissus cumanensis da Colômbia

Introducción. Los venenos de serpientes representan una fuente importante de proteínas y péptidos, los cuales exhiben diversas actividades biológicas, tales como antibacterianas, antiparasitarias, antivi-rales, antitumorales, antifúngicas y contra la agregación plaquetaria, entre otras.Las fosfolipasas A2 presentes en los venenos de serpientes son las proteínas más estudiadas en estos modelos. Se ha demostrado que las fosfolipasas A2, activas e inactivas, poseen actividad catalítica contra células tumorales. Objetivo. Aislar, purificar y caracterizar la fosfolipasa A2 del veneno de Crotalus durissus cumanensis para evaluar su actividad antitumoral in vitro. Materiales y métodos. El aislamiento, la purificación y la identificación de la crotoxina B se hizo mediante la cromatografía de exclusión molecular, la cromatografía líquida de alto rendimiento de fase inversa (Reversed Phase High-Performance Liquid Chromatography, RP-HPLC) y la espectrometría de masas. El efecto citotóxico sobre células tumorales (K562) y células normales (células mononucleares de sangre periférica) se determinó utilizando la técnica de MTT. Resultados. La separación y posterior identificación de la crotoxina B del veneno de C. d. cumanensis de Colombia, permitieron evidenciar que esta fosfolipasa A2 posee efecto citotóxico sobre las células mononucleares de sangre periférica con una dosis de 18,23 ± 0,57 µg/ml, mientras que, para las células K562, fue de 2,34 ± 0,199 µg/ml. Conclusiones. Los resultados sugieren la posibilidad de utilizar la crotoxina B aislada del veneno de C. d. cumanensis como un posible recurso terapéutico para su aplicación en humanos.

Introduction. Snake venoms are an important source of proteins and peptides, which display various biological activities such as antibacterial, antiparasitic, antiviral, antitumor, antifungal and against platelet aggregation, among others.Phospholipases A2 present in snake venoms are the most studied proteins in these models. Active and inactive A2 phospholipases have been shown to possess catalytic activity against tumor cells. Objective. To isolate, purify and characterize the phospholipase A2 of the venom of Crotalus durissus cumanensis to evaluate its in vitro antitumor activity. Materials and methods. Isolation, purification and identification of crotoxin B was done with Size Exclusion Chromatography, Reversed Phase High-Performance Liquid Chromatography, RP-HPLC, and Mass Spectrometry. The cytotoxic effect on tumor cells (K562) and normal cells (peripheral blood mononuclear cells) was determined using the MTT technique. Results. The separation and subsequent identification of crotoxin B, found in the venom of C. d. cumanensis from Colombia, showed that this phospholipase A2 has a cytotoxic effect on peripheral blood mononuclear cells at a dose of 18.23 ± 0.57 µg / ml, whereas for K562 cells, it was 2.34 ± 0.199 µg/ml Conclusions. The results suggest the use of crotoxin B, isolated from the venom of C. d. cumanensis, as a possible therapeutic resource for human application.

Introdução. Os venenos da serpentes constituem uma importante fonte de proteínas e péptidos, os quais exibem várias actividades biológicas, tais como agentes antibacterianos, antiparasitárias, antivi-rais, antitumorais, antifúngicas e contra a agregação de plaquetas, entre outros. As fosfolipases A2 presentes no veneno da serpentes são as proteínas mais estudadas nestes modelos. Tem sido demostrado que as fosfolipases A2, activas e inactivas, possuem actividade catalítica contra células tumorais. Objetivo. Isolar, purificar e caracterizar a fosfolipase A2 do veneno da Crotalus durissus cumanensis para avaliar a sua actividade anti-umoral in vitro. Materiais e métodos. O isolamento, a purificação e identificação da crotoxina B foi realizada por cromatografia de exclusão molecular, cromatografia líquida de alta eficiência de fase reversa (Reversed Phase High-Performance Liquid Chromatography, RP-HPLC) e espectrometria de massa. O efeito cito-tóxico sobre células tumorais (K562) e células normais (células mononucleares do sangue periférico) foi determinada usando a técnica de MTT. Resultados. A Separação e subsequente identificação da crotoxina B do veneno da C. d. cumanensis da Colômbia, permitiu constatar que esta fosfolipase A2 tem um efeito citotóxico em células mono-nucleares de sangue periférico, com uma dose de 18,23 ± 0,57 µg/ ml, enquanto que para as células K562, foi 2,34 ± 0,199 ug/ml. Conclusões. Os resultados sugerem a possibilidade de utilizar crotoxina B isolada a partir do veneno da C. d. cumanensis como recurso para o potencial uso terapêutico em humanos.

Crotalus durissus terrificus crotapotin naturally displays preferred positions for amino acid substitutions

Abstract Background Classically, Crotalus durissus terrificus (Cdt) venom can be described, according to chromatographic criteria, as a simple venom, composed of four major toxins, namely: gyroxin, crotamine, crotoxin and convulxin. Crotoxin is a non-covalent heterodimeric neurotoxin constituted of two subunits: an active phospholipase A2 and a chaperone protein, termed crotapotin. This molecule is composed of three peptide chains connected by seven disulfide bridges. Naturally occurring variants/isoforms of either crotoxin or crotapotin itself have already been reported. Methods The crude Cdt venom was separated by using RP-HPLC and the toxins were identified by mass spectrometry (MS). Crotapotin was purified, reduced and alkylated in order to separate the peptide chains that were further analyzed by mass spectrometry and de novo peptide sequencing. Results The RP-HPLC profile of the isolated crotapotin chains already indicated that the chain would present isoforms, which was corroborated by the MS and tandem mass spectrometry analyses. Conclusion It was possible to observe that the Cdt crotapotin displays a preferred amino acid substitution pattern present in the chain, at positions 31 and 40. Moreover, substitutions could also be observed in and chains (one for each). The combinations of these four different peptides, with the already described chains, would produce ten different crotapotins, which is compatible to our previous observations for the Cdt venom.

Antivenomics as a tool to improve the neutralizing capacity of the crotalic antivenom: a study with crotamine

Abstract Background Snakebite treatment requires administration of an appropriate antivenom that should contain antibodies capable of neutralizing the venom. To achieve this goal, antivenom production must start from a suitable immunization protocol and proper venom mixtures. In Brazil, antivenom against South American rattlesnake (Crotalus durissus terrificus) bites is produced by public institutions based on the guidelines defined by the regulatory agency of the Brazilian Ministry of Health, ANVISA. However, each institution uses its own mixture of rattlesnake venom antigens. Previous works have shown that crotamine, a toxin found in Crolatus durissus venom, shows marked individual and populational variation. In addition, serum produced from crotamine-negative venoms fails to recognize this molecule. Methods In this work, we used an antivenomics approach to assess the cross-reactivity of crotalic antivenom manufactured by IVB towards crotamine-negative venom and a mixture of crotamine-negative/crotamine-positive venoms. Results We show that the venom mixture containing 20% crotamine and 57% crotoxin produced a strong immunogenic response in horses. Antivenom raised against this venom mixture reacted with most venom components including crotamine and crotoxin, in contrast to the antivenom raised against crotamine-negative venom. Conclusions These results indicate that venomic databases and antivenomics analysis provide a useful approach for choosing the better venom mixture for antibody production and for the subsequent screening of antivenom cross-reactivity with relevant snake venom components.

Antivenomics as a tool to improve the neutralizing capacity of the crotalic antivenom: a study with crotamine

Background Snakebite treatment requires administration of an appropriate antivenom that should contain antibodies capable of neutralizing the venom. To achieve this goal, antivenom production must start from a suitable immunization protocol and proper venom mixtures. In Brazil, antivenom against South American rattlesnake (Crotalus durissus terrificus) bites is produced by public institutions based on the guidelines defined by the regulatory agency of the Brazilian Ministry of Health, ANVISA. However, each institution uses its own mixture of rattlesnake venom antigens. Previous works have shown that crotamine, a toxin found in Crolatus durissus venom, shows marked individual and populational variation. In addition, serum produced from crotamine-negative venoms fails to recognize this molecule. Methods In this work, we used an antivenomics approach to assess the cross-reactivity of crotalic antivenom manufactured by IVB towards crotamine-negative venom and a mixture of crotamine-negative/crotamine-positive venoms. Results We show that the venom mixture containing 20% crotamine and 57% crotoxin produced a strong immunogenic response in horses. Antivenom raised against this venom mixture reacted with most venom components including crotamine and crotoxin, in contrast to the antivenom raised against crotamine-negative venom. Conclusions These results indicate that venomic databases and antivenomics analysis provide a useful approach for choosing the better venom mixture for antibody production and for the subsequent screening of antivenom cross-reactivity with relevant snake venom components.(AU)

Crotalus durissus terrificus crotapotin naturally displays preferred positions for amino acid substitutions

Background: Classically, Crotalus durissus terrificus (Cdt) venom can be described, according to chromatographic criteria, as a simple venom, composed of four major toxins, namely: gyroxin, crotamine, crotoxin and convulxin. Crotoxin is a non-covalent heterodimeric neurotoxin constituted of two subunits: an active phospholipase A2 and a chaperone protein, termed crotapotin. This molecule is composed of three peptide chains connected by seven disulfide bridges. Naturally occurring variants/isoforms of either crotoxin or crotapotin itself have already been reported. Methods: The crude Cdt venom was separated by using RP-HPLC and the toxins were identified by mass spectrometry (MS). Crotapotin was purified, reduced and alkylated in order to separate the peptide chains that were further analyzed by mass spectrometry and de novo peptide sequencing. Results: The RP-HPLC profile of the isolated crotapotin chains already indicated that the α chain would present isoforms, which was corroborated by the MS and tandem mass spectrometry analyses. Conclusion: It was possible to observe that the Cdt crotapotin displays a preferred amino acid substitution pattern present in the α chain, at positions 31 and 40. Moreover, substitutions could also be observed in ß and γ chains (one for each). The combinations of these four different peptides, with the already described chains, would produce ten different crotapotins, which is compatible to our previous observations for the Cdt venom.(AU)

New insights into the structural characteristics of irradiated crotamine

Background: Since ionizing radiation has the potential to alter the molecular structure and affect the biologica properties of biomolecules, it has been successfully employed to attenuate animal toxins. The present study aimed to characterize the structural modifications on irradiated crotamine, a toxin from Crotalus durissus terrificus venom, using circular dichroism (CD), fluorescence, Fourier transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). Methods: A combination of size exclusion and ion-exchange chromatography was used to purify the peptide using crude venom. The pure toxin was then submitted to 2 kGy gamma irradiation doses from a cobalt-60 source. Native and irradiated crotamine were analyzed using a fluorescence spectrophotometer. Wavelength was fixed at 295 nm and fluorescence emission scans were collected from 300 to 400 nm. CD and FTIR techniques were used to identify the secondary structure of both samples. DSC analyses were performed at a starting temperature of 20 °C up to a final temperature of 90 °C. AFM provided a 3D profile of the surfaces of both crotamine forms adsorbed on mica. Results: Fluorescence spectroscopy showed that the quantum yield of the irradiated form decreased. CD spectra of native and irradiated crotamine solutions showed differences between the samples in wavelength, indicating that irradiation induced a transition of a small portion of the random coil regions towards an a-helical conformation. FTIR and CD showed that the native and irradiated crotamine spectra were different with regard to secondary structure. The thermodynamic analysis showed that irradiation caused changes in the calorimetric profile and CD showed that temperature-induced changes also occur in the secondary structure. Finally, AFM showed the possible formation of insoluble aggregates. Conclusions: Our results indicate that irradiation leads to progressive changes in the structure of the toxin, which could explain a decrease in myotoxic activity.

Bordonein-L, a new L-amino acid oxidase from Crotalus durissus terrificus snake venom: isolation, preliminary characterization and enzyme stability

Background Crotalus durissus terrificus venom (CdtV) is one of the most studied snake venoms in Brazil. Despite presenting several well known proteins, its L-amino acid oxidase (LAAO) has not been studied previously. This study aimed to isolate, characterize and evaluate the enzyme stability of bordonein-L, an LAAO from CdtV.Methods The enzyme was isolated through cation exchange, gel filtration and affinity chromatography, followed by a reversed-phase fast protein liquid chromatography to confirm its purity. Subsequently, its N-terminal amino acid sequence was determined by Edman degradation. The enzyme activity and stability were evaluated by a microplate colorimetric assay and the molecular mass was estimated by SDS-PAGE using periodic acid-Schiff staining and determined by mass spectrometry.Results The first 39 N-terminal amino acid residues exhibited high identity with other snake venom L-amino acid oxidases. Bordonein-L is a homodimer glycoprotein of approximately 101 kDa evaluated by gel filtration. Its monomer presents around 53 kDa estimated by SDS-PAGE and 58,702 Da determined by MALDI-TOF mass spectrometry. The enzyme exhibited maximum activity at pH 7.0 and lost about 50 % of its activity after five days of storage at 4 °C. Bordonein-Ls activity was higher than the control when stored in 2.8 % mannitol or 8.5 % sucrose.Conclusions This research is pioneering in its isolation, characterization and enzyme stability evaluation of an LAAO from CdtV, denominated bordonein-L. These results are important because they increase the knowledge about stabilization of LAAOs, aiming to increase their shelf life. Since the maintenance of enzymatic activity after long periods of storage is essential to enable their biotechnological use as well as their functional studies.

New insights into the structural characteristics of irradiated crotamine

Background:Since ionizing radiation has the potential to alter the molecular structure and affect the biologica properties of biomolecules, it has been successfully employed to attenuate animal toxins. The present study aimed to characterize the structural modifications on irradiated crotamine, a toxin from Crotalus durissus terrificus venom, using circular dichroism (CD), fluorescence, Fourier transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM) and differential scanning calorimetry (DSC).Methods:A combination of size exclusion and ion-exchange chromatography was used to purify the peptide using crude venom. The pure toxin was then submitted to 2 kGy gamma irradiation doses from a cobalt-60 source. Native and irradiated crotamine were analyzed using a fluorescence spectrophotometer. Wavelength was fixed at 295 nm and fluorescence emission scans were collected from 300 to 400 nm. CD and FTIR techniques were used to identify the secondary structure of both samples. DSC analyses were performed at a starting temperature of 20 °C up to a final temperature of 90 °C. AFM provided a 3D profile of the surfaces of both crotamine forms adsorbed on mica.Results:Fluorescence spectroscopy showed that the quantum yield of the irradiated form decreased. CD spectra of native and irradiated crotamine solutions showed differences between the samples in wavelength, indicating that irradiation induced a transition of a small portion of the random coil regions towards an a-helical conformation. FTIR and CD showed that the native and irradiated crotamine spectra were different with regard to secondary structure. The thermodynamic analysis showed that irradiation caused changes in the calorimetric profile and CD showed that temperature-induced changes also occur in the secondary structure. Finally, AFM showed the possible formation of insoluble aggregates.Conclusions:Our results indicate that irradiation leads to progressive changes in the structure of the toxin, which could explain a decrease in myotoxic activity.(AU)

Bordonein-L, a new L-amino acid oxidase from Crotalus durissus terrificus snake venom: isolation, preliminary characterization and enzyme stability

Background Crotalus durissus terrificus venom (CdtV) is one of the most studied snake venoms in Brazil. Despite presenting several well known proteins, its L-amino acid oxidase (LAAO) has not been studied previously. This study aimed to isolate, characterize and evaluate the enzyme stability of bordonein-L, an LAAO from CdtV.Methods The enzyme was isolated through cation exchange, gel filtration and affinity chromatography, followed by a reversed-phase fast protein liquid chromatography to confirm its purity. Subsequently, its N-terminal amino acid sequence was determined by Edman degradation. The enzyme activity and stability were evaluated by a microplate colorimetric assay and the molecular mass was estimated by SDS-PAGE using periodic acid-Schiff staining and determined by mass spectrometry.Results The first 39 N-terminal amino acid residues exhibited high identity with other snake venom L-amino acid oxidases. Bordonein-L is a homodimer glycoprotein of approximately 101 kDa evaluated by gel filtration. Its monomer presents around 53 kDa estimated by SDS-PAGE and 58,702 Da determined by MALDI-TOF mass spectrometry. The enzyme exhibited maximum activity at pH 7.0 and lost about 50 % of its activity after five days of storage at 4 °C. Bordonein-L's activity was higher than the control when stored in 2.8 % mannitol or 8.5 % sucrose.Conclusions This research is pioneering in its isolation, characterization and enzyme stability evaluation of an LAAO from CdtV, denominated bordonein-L. These results are important because they increase the knowledge about stabilization of LAAOs, aiming to increase their shelf life. Since the maintenance of enzymatic activity after long periods of storage is essential to enable their biotechnological use as well as their functional studies.(AU)

Determinação das concentrações plasmáticas de proteínas e metabólitos de cascavéis em cativeiro / Determination of proteins and metabolites concentrations in plasma of rattlesnakes in captivity

Para determinar as concentrações plasmáticas de proteínas e metabólitos de cascavéis em cativeiro, foram utilizadas 60 serpentes adultas, sendo 30 machos e 30 fêmeas. O sangue foi coletado através de punção do seio venoso paravertebral cervical e armazenado em tubos com heparina. As análises bioquímicas foram processadas colorimetricamente em Analisador Automático de Bioquímica Chemwell (Awareness Technology®, Inc). Foram calculadas as médias e desvios padrão dos seguintes constituintes: proteínas totais, albumina, globulinas, relação albumina/globulinas, ácido úrico, creatinina, ureia, colesterol, colesterol HDL e triglicérides. Os valores obtidos foram semelhantes aos descritos na literatura para repteis e serpentes, sendo as diferenças observadas provavelmente decorrentes da diferença entre espécies, clima, estação do ano e metodologia utilizada. Não houve diferenças significativas entre machos e fêmeas para os parâmetros estudados. Estes resultados podem ser úteis no estabelecimento de valores de referência para planos de conservação destes ofídios em cativeiro.(AU)

For determining plasma concentrations of proteins and metabolites of rattlesnakes in captivity, 60 adult snakes, 30 males and 30 females were used. Blood was collected by puncture of the cervical paravertebral venous sinus and stored in tubes with heparin. Biochemical analyzes were colorimetrically processed using an Automatic Biochemistry Analyzer Chemwell (Awareness Technology®, Inc). The mean and standard deviation were calculated for the following constituents: total protein, albumin, globulin, albumin/globulin ratio, uric acid, creatinine, urea, cholesterol, HDL cholesterol and triglycerides. The values were similar to those previously reported for reptiles and snakes, with the differences observed probably due to the difference between species, climate, season and the methodology used. There were no significant differences between males and females for the parameters studied. These results may be useful in establishing normal biochemical values for conservation plans for these snakes in captivity.(AU)