Effect of Seaweed-Derived Fucoidans from Undaria pinnatifida and Fucus vesiculosus on Coagulant, Proteolytic, and Phospholipase A 2 Activities of Snake Bothrops jararaca , B. jararacussu , and B. neuwiedi Venom

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. This study analyzed the potential of two fucoidan sulfated polysaccharides extracted from brown seaweeds (FVF) and (UPF) against the fibrinogen or plasma coagulation, proteolytic, and phospholipase A (PLA ) activities of , , and venom. The toxicity of FVF and UPF was assessed by the hemocompatibility test. FVF and UPF did not lyse human red blood cells. FVF and UPF inhibited the proteolytic activity of , , and venom by approximately 25%, 50%, and 75%, respectively, while all venoms led to a 20% inhibition of PLA activity. UPF and FVF delayed plasma coagulation caused by the venoms of and but did not affect the activity of venom. FVF and UPF blocked the coagulation of fibrinogen induced by all these Bothropic venoms. FVF and UPF may be of importance as adjuvants for SBE caused by species of , which are the most medically relevant snakebite incidents in South America, especially Brazil.