Exploiting the antithrombotic effect of the (pro)thrombin inhibitor bothrojaracin
Research article published in Toxicon (2016)
Abstract
Bothrojaracin is a 27 kDa C-type lectin-like protein from Bothrops jararaca snake venom. It behaves as a potent thrombin inhibitor upon high-affinity binding to thrombin exosites. Bothrojaracin also forms a stable complex with prothrombin that can be detected in human plasma. Formation of the zymogen-inhibitor complex severely decreases prothrombin activation and contributes to the anticoagulant activity of bothrojaracin. In the present study, we employed two rodent models to evaluate the antithrombotic effect of bothrojaracin in vivo: stasis-induced thrombosis and thrombin-induced pulmonary thromboembolism. It was observed that bothrojaracin interacts with rat prothrombin in plasma. Ex-vivo assays showed stable complex formation even after 24 h of a single bothrojaracin dose. As a result, bothrojaracin showed significant antithrombotic activity in a rat venous thrombosis model elicited by thromboplastin combined with stasis. The antithrombotic activity of bothrojaracin (1 mg/kg) persisted for up to 24 h and it was associated with moderate bleeding as assessed by a tail transection method. Formation of bothrojaracin-prothrombin complex has been also observed following intravenous administration of the inhibitor into mice. As a result, bothrojaracin effectively protected mice from thrombin-induced fatal thromboembolism. We conclude that bothrojaracin is a potent antithrombotic agent in vivo and may serve as a prototype for the development of new zymogen-directed drugs that could result in prolonged half-life and possible decreased hemorrhagic risk.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Summary
Exploiting the antithrombotic effect of the (pro)thrombin inhibitor bothrojaracin.
Why This Matters for Hirudotherapy
This study evaluated the antithrombotic effects of bothrojaracin, a 27 kDa C-type lectin-like protein from Bothrops jararaca snake venom that binds thrombin exosites and forms a stable complex with prothrombin, thereby inhibiting thrombin and severely decreasing prothrombin activation. Using rat stasis-induced thrombosis and mouse thrombin-induced pulmonary thromboembolism models, bothrojaracin demonstrated significant antithrombotic activity persisting up to 24 hours (with moderate bleeding) and protected mice from fatal thromboembolism, with stable prothrombin complex formation detectable ex vivo. For ASH's domain, the relevance is indirect but conceptually substantive: bothrojaracin is a thrombin inhibitor from a natural source (snake venom), paralleling hirudin from leech saliva, and may inform broader understanding of naturally derived anticoagulants. However, no leeches or leech-derived molecules are involved, the study is entirely preclinical (rodent models), and the findings pertain to snake venom pharmacology rather than hirudotherapy.
Citation
Exploiting the antithrombotic effect of the (pro)thrombin inhibitor bothrojaracin
Assafim M et al. · Toxicon, 2016
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