Anticoagulants from scorpion venoms

Abstract

Venom from at least six distinct families of scorpion: Buthidae, Caraboctonidae, Iuridae, Ischnuridae, Scorpionidae and Vejovidae are known to contain many pharmacologically active peptides and some proteins involved in coagulation. The list of such compounds is increasing with time and newly described cases. Earlier reports performed with venom from Buthus tamulus and Palamneus gravimanus have shown the presence of coagulopathy in experimental animals. Other scorpion species such as: Hottentotta judaicus, Heterometrus spinnifer, Heterometrus fulvipes, Parabuthus transvaalicus, Androctonus australis, Scorpio maurus palmatus and Leiurus quinquestriatus habraeus were reported to contain components implicated in coagulation. From Buthus marthensi Karsch a venom active polypeptide (SVAP) that causes platelet aggregation in vivo and in vitro was described. A gene cloned from the same scorpion coding for a putative peptide named BmKAPi was reported. Its deduced amino acid sequence shows similarities to anticoagulant peptides and proteinase inhibitors from other species of animals. One of the best characterized components was Imperatoxin inhibitor (IpTxi) from the African scorpion Pandinus imperator Hector, described as a heterodimeric protein in which the major subunit has an amino acid sequence similar to known phospholipases (PLA2) from pancreas and snake venoms. The venom from the Mexican scorpion Anuroctonus phaiodactylus was reported to cause delay of clotting time of human platelet rich plasma (PRP) and poor platelet plasma (PPP). Several heterodimeric phospholipases and genes coding for similar ones were described from the venomous glands of this species. Recently, the venom from the Venezuelan scorpion Tityus discrepans was shown to induce inflammation, partial thromboplastin time (PTT) and prothrombin time (PT). Also recently venom from Hadrurus gertschi and Opisthacanthus cayaporum were reported to contain phospholipase enzymes. Thus far none of the well documented cases of snake venom components that interfere with blood coagulation such as: serine proteases, metalloproteinases, C- type lectins, disintegrins have been identified in scorpion venom. This communication revises the state of art in this subject.