Effect of Seaweed-Derived Fucoidans from Undaria pinnatifida and Fucus vesiculosus on Coagulant, Proteolytic, and Phospholipase A2 Activities of Snake Bothrops jararaca, B. jararacussu, and B. neuwiedi Venom

BACKGROUND

Snakebite envenomation (SBE) causes diverse toxic effects in humans, including disability and death. Current antivenom therapies effectively prevent death but fail to block local tissue damage, leading to an increase in the severity of envenomation; thus, seeking alternative treatments is crucial.

METHODS

This study analyzed the potential of two fucoidan sulfated polysaccharides extracted from brown seaweeds Fucus vesiculosus (FVF) and Undaria pinnatifida (UPF) against the fibrinogen or plasma coagulation, proteolytic, and phospholipase A2 (PLA2) activities of Bothrops jararaca, B. jararacussu, and B. neuwiedi venom. The toxicity of FVF and UPF was assessed by the hemocompatibility test.

RESULTS

FVF and UPF did not lyse human red blood cells. FVF and UPF inhibited the proteolytic activity of Bothrops jararaca, B. jararacussu, and B. neuwiedi venom by approximately 25%, 50%, and 75%, respectively, while all venoms led to a 20% inhibition of PLA2 activity. UPF and FVF delayed plasma coagulation caused by the venoms of B. jararaca and B. neuwiedi but did not affect the activity of B. jararacussu venom. FVF and UPF blocked the coagulation of fibrinogen induced by all these Bothropic venoms.

CONCLUSION

FVF and UPF may be of importance as adjuvants for SBE caused by species of Bothrops, which are the most medically relevant snakebite incidents in South America, especially Brazil.

Proteomics and life-history variability of Endogenous Phospholipases A2 Inhibitors (PLIs) in Bothrops jararaca plasma

In Brazil, the genus Bothrops is responsible for most ophidian accidents. Snake venoms have a wide variety of proteins and peptides exhibiting a broad repertoire of pharmacological and toxic effects that elicit systemic injury and characteristic local effects. The snakes' natural resistance to envenomation caused by the presence of inhibitory compounds on their plasma have been extensively studied. However, the presence of these inhibitors in different developmental stages is yet to be further discussed. The aim of this study was to evaluate the ontogeny of Bothrops jararaca plasma inhibitor composition and, to this end, plasma samples of B. jararaca were obtained from different developmental stages (neonates, youngs, and adults) and sexes (female and male). SDS-PAGE, Western blotting, affinity chromatography, and mass spectrometry were performed to analyze the protein profile and interaction between B. jararaca plasma and venom proteins. In addition, the presence of γBjPLI, a PLA2 inhibitor previously identified and characterized in B. jararaca serum, was confirmed by Western blotting. According to our results, 9-17% of plasma proteins were capable of binding to venom proteins in the three developmental stages. The presence of different endogenous inhibitors and, more specifically, different PLA2 inhibitor (PLI) classes and antihemorrhagic factors were confirmed in specimens of B. jararaca from newborn by mass spectrometry. For the first time, the αPLI and βPLI were detected in B. jararaca plasma, although low or no ontogenetic and sexual correlation were found. The γPLI were more abundant in adult female, than in neonate and young female, but similar to neonate, young and adult male according to the results of mass spectrometry analysis. Our results suggest that there are proteins in the plasma of these animals that can help counteract the effects of self-envenomation from birth.

Panicolytic-like effects of environment enrichment on male mice threatened by Bothrops jararaca lancehead pit vipers

Environment enrichment (EE) is a well-known eustress model showing beneficial effects in different psychiatric diseases, but its positive properties in panic disorders are not yet established. The confrontation between prey and predator in complex arenas has been validated as a putative panic attack model. The principal aim of this work was to investigate the role of the EE on panic-like defensive responses elicited by mice threatened by venomous snakes. After 6 weeks of exposure either to an enriched or standard environments, 36 male mice were habituated in a complex polygonal arena for snakes containing an artificial burrow and elevated platforms for escape. The animals were confronted by Bothrops jararaca for 5 min, and the following antipredatory responses were recorded: defensive attention, stretched attend posture, flat back approach, prey versus predator interaction, oriented escape behavior, time spent in a safe place, and number of crossings. Mice threatened by snakes displayed several antipredatory reactions as compared to the exploratory behavior of those animals submitted to a nonthreatening situation (toy snake) in the same environment. Notably, EE causes anxiolytic- and panicolytic-like effects significantly decreasing the defensive attention and time spent in safe places and significantly increasing both prey versus predator interaction and exploratory behavior. In conclusion, our data demonstrate that EE can alter the processing of fear modulation regarding both anxiety- and panic-like responses in a dangerous condition, significantly modifying the decision-making defensive strategy.

Hemoperitoneum after a Bothrops snakebite: Case report

Snakebites are frequent in tropical countries. Brazil has an average of 27,000 cases per year, with a fatality rate of 0.5%, and the Bothrops genus is the most common causative agent, accounting for about 70-90% of the accidents. This report describes a case of human envenomation by a juvenile Bothrops jararaca snake in São Paulo, Brazil, in a 71 years-old man, previously healthy. He presented a life-threatening envenomation, which developed to severe hypotension, acute kidney injury and extensive peritoneal hemorrhage. The hemoperitoneum was diagnosed due to persistent hypotension associated with anemia, pain and gastrointestinal complaints. Abdominal Computed Tomography scans showed a moderate to large amount of presumable hematic material inside the abdominal cavity, predominantly in the perihepatic and perisplenic spaces. The intra-abdominal hemorrhage was not surgically addressed, and the patient was discharged 5 days after hospitalization, with the progressive absorption of the hemoperitoneum. Systemic bleeding is one of the complications and main causes of death in Bothrops envenomations. Acute peritoneal hemorrhage is one of these serious complications that must be carefully addressed since its management must take into account the risk of bleeding caused by toxins that affect hemostasis. The case described highlights the importance of early diagnosis and adequate management of this potentially fatal complication in snakebites.