RESUMO
Protozoal infections are a world-wide problem. The toxicity and somewhat low effectiveness of the existing drugs require the search for new ways of protozoa suppression. Snake venom contains structurally diverse components manifesting antiprotozoal activity; for example, those in cobra venom are cytotoxins. In this work, we aimed to characterize a novel antiprotozoal component(s) in the Bungarus multicinctus krait venom using the ciliate Tetrahymena pyriformis as a model organism. To determine the toxicity of the substances under study, surviving ciliates were registered automatically by an original BioLaT-3.2 instrument. The krait venom was separated by three-step liquid chromatography and the toxicity of the obtained fractions against T. pyriformis was analyzed. As a result, 21 kDa protein toxic to Tetrahymena was isolated and its amino acid sequence was determined by MALDI TOF MS and high-resolution mass spectrometry. It was found that antiprotozoal activity was manifested by ß-bungarotoxin (ß-Bgt) differing from the known toxins by two amino acid residues. Inactivation of ß-Bgt phospholipolytic activity with p-bromophenacyl bromide did not change its antiprotozoal activity. Thus, this is the first demonstration of the antiprotozoal activity of ß-Bgt, which is shown to be independent of its phospholipolytic activity.
RESUMO
It is well-known that drugs administered into an organism intravenously or through the gastrointestinal tract are degraded by enzymes of the body, reducing their therapeutic effect. One of the ways to decrease this undesirable process is through the inclusion of drugs in nanomaterials. Earlier strong anticoagulant activity was demonstrated for dipeptide IleTrp (IW) and adenosine (Ado). In this work, the effect of inclusion in nanomaterials on the biological activity of IW and Ado was studied. For this purpose, Ado and IW were incorporated into thermosensitive nanogel composed of pluronic P123-grafted heparin. The prepared nanocarrier was characterized by transmission electron microscopy, dynamic light scattering, and ζ-potential. Biological activity was determined by measuring the bleeding time from mouse tail in vivo and the time of clot formation in vitro. It was found that encapsulation of Ado and IW into nanomaterial significantly increased their effects, resulting in an increase in the bleeding time from mouse tail and clot formation time. Thus, inclusion of low molecular weight anticoagulants Ado and IW into nanomaterials may be considered a way to increase their biological activity.
RESUMO
Scorpion venoms are complex polypeptide mixtures, the ion channel blockers and antimicrobial peptides being the best studied components. The coagulopathic properties of scorpion venoms are poorly studied and the data about substances exhibiting these properties are very limited. During research on the Heterometrus laoticus scorpion venom, we have isolated low-molecular compounds with anticoagulant activity. Determination of their structure has shown that one of them is adenosine, and two others are dipeptides LeuTrp and IleTrp. The anticoagulant properties of adenosine, an inhibitor of platelet aggregation, are well known, but its presence in scorpion venom is shown for the first time. The dipeptides did not influence the coagulation time in standard plasma coagulation tests. However, similarly to adenosine, both peptides strongly prolonged the bleeding time from mouse tail and in vitro clot formation in whole blood. The dipeptides inhibited the secondary phase in platelet aggregation induced by ADP, and IleTrp decreased an initial rate of platelet aggregation induced by collagen. This suggests that their anticoagulant effects may be realized through the deterioration of platelet function. The ability of short peptides from venom to slow down blood coagulation and their presence in scorpion venom are established for the first time. Further studies are needed to elucidate the precise molecular mechanism of dipeptide anticoagulant activity.
