Poster 075 - Natural and synthetic phospholipases A2 inhibitors (PLIs): Inhibition of PLA2s isolated

Poster 75. Congresso da Sociedade Brasileira de Toxinologia, 8., Symposium of the Pan American Section of the International Society on Toxinology, 8., 2004, Angra dos Reis, Brasil. Abstracts... J. Venom. Anim. Toxins incl.Trop. Dis., 2004, 10, 3, p.434.

Natural and Synthetic PhospholipasesA2 Inhibitors (PLIs): Inhibition of PLA2s isolated from Bothrops jararacussuSnake Venom.

^1,2Marcussi, S.; ¹Fernandes, V. C.; ¹Silveira, L. B.; ¹Cambraia, R. S.; ³Ticli, F. K.; ³Sant`Ana, C. D.; ³Mazzi, M. V.; ¹França, S. C.; ³Sampaio, S. V.; ²Giglio, J. R. and ¹Soares, A. M.

1 Unidade de Biotecnologia-UNAERP, Ribeirão Preto-SP; 2 Depto Bioquímica e Imunologia, FMRP-USP, Ribeirao Preto-SP and 3 Depto. Análises Clínicas, Toxicológicas e Bromatológicas-FCFRP-USP, Ribeirão Preto-SP, Brasil.

The high involvement of snake venom PLA2s in different physiopathological processes resulted in a crescent search of their natural and artificial inhibitors (PLIs), aiming nut only at their inhibitory effect, but also at their interaction with target PLA2s. This work reports the inhibitory properties of several PLIs upon three PLA2s homologues from B. jararacussu snake venom, namely: basic Lys49-BthTX-I, basic Asp49-BthTX-II and acidic Asp49-BthA-I-PLA2. Different synthetic (EDTA, BPB and manoalid B) and natural (heparin, B. moojeni BmjMIP, Lufariellavariabilis manoalid A, Cordiaverbenacea RA and vitamin E) were assayed. Chemical modification induced by BPB abolished the PLA2 and anticoagulant activities of BthTX-II and BthA-I-PLA2. The liposome disrupting activity of both Asp-49 PLA2s and the edema-inducing activity of all PLA2s were partially inhibited. Modification by BPB changed also the effect of Asp-49 PLA2s upon platelets and blood pressure. Incubation with EDTA resulted in total inhibition of the Asp-49 PLA2s enzymatic activity, in addition to a decrease of the liposome-disrupting, myotoxic, cytotoxic and edema-inducing activity of BthTX-II, as well as of the liposome-disrupting activity of BthA-I-PLA2. Heparin, BmjMIP, RA and manoalids A and B also inhibited the cytotoxic, myotoxic and edema-inducing activity of BthTX-II, as well as the liposome-disrupting activity of BthA-I-PLA2 vitamin E inhibited only the myotoxic activity and partially the enzymatic activity. None of the inhibitors changed the secondary structure or degraded the PLA2s, as shown by SDS-PAGE and circular dichroism. These inhibitors are promising tools for the understanding of the actions mechanism of the PLA2s and for treatment of envenomation by snake bites.