Bothrops sp. snake venoms: Comparison of some biochemical and physicochemical properties and interference in platelet functions

Procoagulant, proteolytic, phospholipase and platelet pro-aggregating and inhibiting activities were screened for pooled venoms of seven Bothrops species as well as Crotalus durissus terrificus and Lachesis muta snakes typical of the Brazilian territory. As reported by other authors, we also found that examination of the electrophoretic and gel filtration patterns of Bothrops snakes venoms could not be used for identification of the species of a given venom because of the lack of marked interspecific differences within the same genus. Our data indicated that B. cotiara, B. alternatus and B. atrox possess no platelet pro-aggregating activity, low inhibitory effect on platelet aggregation and very low or intermediate levels for the other activities. B. moojeni, B. neuwiedi and B. jararacussu whose venoms possess high procoagulant, platelet pro-aggregating and phospholipase activities are low in both proteolytic and platelet inhibitory activities. B. jararaca venom showed the highest inhibitory effect on platelet aggregation and very low platelet pro-aggregating activity. Compared with the Bothrops venoms studied, L. muta venom showed that highest proteolytic activity while C. d. terrificus venom presented remarkable high platelet pro aggregating and phospholipase activities. In all venoms, proteolytic activity could be completely inhibited by EDTA (2 mM) alone. In contrast, the presence of phenylmethylsulfonyl fluoride (5 mM) inhibited partially the caseinolytic activity of all venoms, except that L. muta venom, which was almost completely blocked by this reagent. Altogether, these data confirm the presence of high levels of metalloproteinases in the venoms of Crotalinae snakes. Most of these enzymes are dependent of the availability of Ca²⁺, being much less the same concerning the presence of serine residues in their active sites. The data indicated that the presence and levels of procoagulant, azocaseinolytic and phospholipase A₂ activities alone could not differentiated the species of the Bothrops venoms studied, particularly in the cases of B. jararaca, B. moojeni and B. atrox. However, the platelet inhibiting property of low doses of B. jararaca venom can be useful to differentiate it from B. moojeni venom. In the same way, the platelet pro aggregating activity of high doses of B. jararaca venom may be used to distinguish it from B. atrox crude venom, otherwise very similar but incapable to activate platelets. In conclusion, our comparative screening of biological properties has indicated that platelet studies may serve as a tool to distinguish among venoms that otherwise behave biochemically in a very similar way. Although promising, the general applicability of platelet activation studies by snake venoms for classification or taxanomical purposes has yet to be extended to other family of snakes to be proven useful.