An Evaluation Of 3-rhamnosylquercetin, A Glycosylated Form Of Quercetin, Against The Myotoxic And Edematogenic Effects Of Spla 2 From Crotalus Durissus Terrificus

This paper shows the results of quercitrin effects on the structure and biological activity of secretory phospholipase (sPLA2) from Crotalus durissus terrificus, which is the main toxin involved in the pharmacological effects of this snake venom. According to our mass spectrometry and circular dichroism results, quercetin was able to promote a chemical modification of some amino acid residues and modify the secondary structure of C. d. terrificus sPLA2. Moreover, molecular docking studies showed that quercitrin can establish chemical interactions with some of the crucial amino acid residues involved in the enzymatic activity of the sPLA2, indicating that this flavonoid could also physically impair substrate molecule access to the catalytic site of the toxin. Additionally, in vitro and in vivo assays showed that the quercitrin strongly diminished the catalytic activity of the protein, altered its Vmax and Km values, and presented a more potent inhibition of essential pharmacological activities in the C. d. terrificus sPLA2, such as its myotoxicity and edematogenic effect, in comparison to quercetin. Thus, we concluded that the rhamnose group found in quercitrin is most likely essential to the antivenom activities of this flavonoid against C. d. terrificus sPLA2. © 2014 Daniela de Oliveira Toyama et al

Effects Of Morin On Snake Venom Phospholipase A2 (pla 2)

Flavonoids are potent anti-inflammatory compounds isolated from several plant extracts, and have been used experimentally against inflammatory processes. In this work, a PLA2 isolated from the Crotalus durissus cascavella venom and rat paw oedema were used as a model to study the effect of flavonoids on PLA2. We observed that a treatment of PLA2 with morin induces several modifications in the aromatic amino acids, with accompanying changes in its amino acid composition. In addition, results from circular dichroism spectroscopy and UV scanning revealed important structural modifications. Concomitantly, a considerable decrease in the enzymatic and antibacterial activities was observed, even though anti-inflammatory and neurotoxic activities were not affected. These apparent controversial results may be an indication that PLA2 possess a second pharmacological site which does not affect or depend on the enzymatic activity. © 2005 Elsevier Ltd. 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Crotacetin, A Novel Snake Venom C-type Lectin Homolog Of Convulxin, Exhibits An Unpredictable Antimicrobial Activity

Snake venom (sv) C-type lectins encompass a group of hemorrhagic toxins that are capable of interfering with blood stasis. A very well-studied svC-type lectin is the heterodimeric toxin, convulxin (CVX), from the venom of South American rattlesnake Crotalus durissus terrificus. CVX is able to activate platelets and induce their aggregation by acting via p62/GPVI collagen receptor. By using polymerase chain reaction homology screening, we have cloned several cDNA precursors of CVX subunit homologs. One of them, named crotacetin (CTC) β-subunit, predicts a polypeptide with a topology very similar to the tridimensional conformations of other subunits of CVX-like snake toxins, as determined by computational analysis. Using gel permeation and reverse-phase high-performance liquid chromatography, CTC was purified from C. durissus venoms. CTC can be isolated from the venom of several C. durissus subspecies, but its quantitative predominance is in the venom of C. durissus cascavella. Functional analysis indicates that CTC induces platelet aggregation, and, importantly, exhibits an antimicrobial activity against Gram-positive and -negative bacteria, comparable with CVX. © Copyright 2006 by Humana Press Inc. All rights of any nature whatsoever reserved.443412423Mukherjee, A.K., Maity, C.R., Biochemical composition, lethality and pathophysiology of venom from two cobras - Naja naja and N. kaouthia (2002) Comp. Biochem. Physiol. B. Biochem. Mol. Biol., 131, pp. 125-132Daltry, J.C., Wüster, W., Thorpe, R.S., Diet and snake venom evolution (1996) Nature, 379, pp. 537-540Saravia, P., Rojas, E., Arce, V., Geographic and ontogenic variability in the venom of the Neotropical rattlesnake Crotalus durissus: Pathophysiological and therapeutic implications (2002) Rev. Biol. 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Commun., 310, pp. 478-482Batuwangala, T., Leduc, M., Gibbins, J.M., Bon, C., Jones, E.Y., Structure of the snake-venom toxin convulxin (2004) Acta Crystallogr., 60, p. 46Polgar, J., Clemetson, J.M., Kehrel, B.E., Platelet activation and signal transduction by convulxin, a C-type lectin from Crotalus durissus terrificus (tropical rattlesnake) venom via the p62/GPVI collagen receptor (1997) J. Biol. Chem., 272, pp. 13,576-13,583Hamako, J., Matsui, T., Suzuki, M., Purification and characterization of bitiscetin, a novel von Willebrand factor modulator protein from Bitis arietans snake venom (1996) Biochem. Biophys. Res. 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Umbelliferone Induces Changes In The Structure And Pharmacological Activities Of Bn Iv, A Phospholipase A2 Isoform Isolated From Bothrops Neuwiedi

In this paper was demonstrated that umbelliferone induces changes in structure and pharmacological activities of Bn IV, a lysine 49 secretory phospholipase A2 (sPLA2) from Bothrops neuwiedi. Incubation of Bn IV with umbelliferone virtually abolished platelet aggregation, edema, and myotoxicity induced by native Bn IV. The amino acid sequence of Bn IV showed high sequence similarities with other Lys49 sPLA2s from B. jararacussu (BthTx-I), B. pirajai (PrTx-I), and B. neuwiedi pauloensis (Bn SP6 and Bn SP7). This sPLA2 also has a highly conserved C-terminal amino acid sequence, which has been shown as important for the pharmacological activities of Lys49 sPLA2. Sequencing of Bn IV previously treated with umbelliferone revealed modification of S(1) and S(20). Fluorescent spectral analysis and circular dichroism (CD) studies showed that umbelliferone modified the secondary structure of this protein. Moreover, the pharmacological activity of Bn IV is driven by synergism of the C-terminal region with the α-helix motifs, which are involved in substrate binding of the Asp49 and Lys49 residues of sPLA2 and have a direct effect on the Ca2+-independent membrane damage of some secretory snake venom PLA2. For Bn IV, these interactions are potentially important for triggering the pharmacological activity of this sPLA2. © 2011 Elsevier Ltd.576851860Chan, A.C., Pritchard, E.T., Gerrard, J.M., Man, R.Y., Choy, P.C., Biphasic modulation of platelet phospholipase A2 activity and platelet aggregation by mepacrine (quinacrine) (1982) Biochim. Biophys. 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Jararacussu (2008) Int. J. Mol. Sci., 9 (5), pp. 736-750Diz Filho, E.B., Marangoni, S., Toyama, D.O., Fagundes, F.H., Oliveira, S.C., Fonseca, F.V., Calgarotto, A.K., Toyama, M.H., Enzymatic and structural characterization of new PLA2 isoform isolated from white venom of Crotalus durissus ruruima (2009) Toxicon, 53 (1), pp. 104-114Fawzy, A.A., Vishwanath, B.S., Franson, R.C., Inhibition of human non-pancreatic phospholipases A2 by retinoids and flavonoids. 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