Inhibition of the Coagulant Activity of some  Snake Venoms by a Peptide in the Aqueous Extract from Tabernaemontana catharinensis A.DC. (Apocynaceae)

¹Guiguer, E.L, ¹Ticli, F.K., ¹Cintra, A.C.O., ⁴Giglio, J.R. and ¹Sampaio,S.V.

1 Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, FCFRP - USP, Ribeirão Preto, SP; 2 Departamento de Bioquímica e Imunologia, FMRP- USP, Ribeirão Preto, SP.

The most prominent systemic effect induced by Bothrops snakebite envenomation originates from blood clotting alterations, whose local effects include myonecrosis, hemorrhage and edema. Tabernaemontanacatharinensis has been proved efficient in the treatment of local and systemic effects induced by Crotalusdurissus terrifecus, Bothropsjararaca and Bothrops jararacussu venom. The aqueous extract from T. catharinensis was submitted to a two-step fractionation, starting with a gel filtration on Sephadex G-10, werefrom eight fractions, named PI to PVIII, were obtained, from which PII was able to inhibit 81% of the coagulant activity of B. jararacussu venom, followed by a HPLC step which resolved PII into two subfractions, PIIA and PIIB, the former inhibiting 92% of the clotting activity, while the latter was inactive toward citrated blood plasma. At a 1:10 molar ratio of the PIIA fraction the coagulant activity of some snake venoms were inhibit in: Bothrops pirajai (95%), Bothrops jararacussu (70%), Bothrops moojeni (70%) and Crotalus durissus terrificus (70%). Preliminary determination of the amino acid composition and sequencing indicated that PIIA, a small peptide, Pro-Arg-Gly-Gly, as the only detected component which might be responsible for the anticoagulant activity of the plant extract. Further purification of this peptide and complementary proofs of its sequence by synthesis will be useful as a molecular model of an antithrombotic agent.

Support: FAPESP and CNPq.

Correspondence to: accintra@fcfrp.usp.br