Characterization of a New Platelet Aggregating Factor from Crotoxin Crotalus durissus cascavella Venom

The First Anti-Snakebite and Hepatoprotective Characterization of a Trypsin Kunitz-like Inhibitor (EcTI) from the Plant Enterolobium contortisiliquum; A Case of Two Soul Mates Meeting

Snake venom serine protease (SVSP) interferes with the regulation and control of important biological reactions in homeostasis and can be classified as an activator of the fibrinolytic system and platelet aggregation. Our group has recently isolated a new serine protease from Crotalus durissus terrificus total venom (Cdtsp-2). This protein exhibits edematogenic capacity and myotoxic activity. A Kunitz-like EcTI inhibitor protein with a molecular mass of 20 kDa was isolated from Enterolobium contortisiliquum and showed high trypsin inhibition. Thus, the objective of this work is to verify the possible inhibition of the pharmacological activities of Cdtsp-2 by the Kutinz-type inhibitor EcTI. To isolate Cdtsp-2 from total C. d. terrificus venom, we used three-step chromatographic HPLC. Using the mice paw edema model, we observed an edematogenic effect, myotoxicity and hepatotoxicity caused by Cdtsp-2. In vitro and in vivo experiments showed that the alterations in hemostasis caused by Cdtsp-2 are crucial for the development of marked hepatotoxicity and that EcTI significantly inhibits the enzymatic and pharmacological activities of Cdtsp-2. Kunitz-like inhibitor may be a viable alternative for the development of ancillary treatments against the biological activities of venoms.

Sequence determination and bioinformatic comparison of ten venom serine proteases of Trimeresurus gracilis, a Taiwanese endemic pitviper with controversial taxonomy

Trimeresurus gracilis (Tgc) is endemic to Taiwan and shown to be closely related with Ovophis okinavensis by previous phylogenetic analyses, but their taxonomic status remain controversial. Here, we cloned and sequenced ten of its venom serine-proteases (designated as Tgc-vSPs). All the Tgc-vSPs conserve the catalytic triads, six appear to be kallikrein-like (KNs) and four are plasminogen-activator homologs (PAHs and PAs). They are studied under four structural categories: (1) highly similar Tgc-KN1, Tgc-KN2 and Tgc-KN3, with four predicted N-glycosylation sites; (2) Tgc-KN4, with a single N -glycosylation site; (3) Tgc-KN5 and Tgc-KN6, with two distinct N-glycosylation sites; (4) Tgc-PAH1/PAH2, TgcPA3, and Tgc-PA4, with two conserved N-glycosylation sites. Additionally, Tgc-KN1, Tgc-KN4 and Tgc-PAH1 were purified by reversed-phase HPLC and identified by peptide-mass-fingerprinting. Results of BLAST and sequence alignments reveal that Tgc-KN1∼3 and Tgc-KN6 are most like the vSPs of rattlesnakes, while the sequences of Tgc-KN4, KN5 and Tgc-PAH1/PAH2 match closely to the partial sequences of three O. okinavensis vSPs. Thus, our results reveal non-overlapping similarities of Tgc-vSPs to the O. okinavensis vSPs and vSPs of the New World pitvipers. In addition, molecular phylogenetic analyses of the plasminogen-activator like vSPs reveal separate evolution of two clusters of the enzymes with distinct functions.

Evaluation of systemic inflammatory response and lung injury induced by Crotalus durissus cascavella venom

This study investigated the systemic inflammatory response and mechanism of pulmonary lesions induced by Crotalus durissus cascavella venom in murine in the state of Bahia. In order to investigate T helper Th1, Th2 and Th17 lymphocyte profiles, we measured interleukin (IL) -2, IL-4, IL-6, IL-10, IL-17, tumor necrosis factor (TNF) and interferon gamma (IFN-γ) levels in the peritoneal fluid and macerated lungs of mice and histopathological alterations at the specific time windows of 1h, 3h, 6h, 12h, 24h and 48h after inoculation with Crotalus durissus cascavella venom. The data demonstrated an increase of acute-phase cytokines (IL-6 and TNF) in the first hours after inoculation, with a subsequent increase in IL-10 and IL-4, suggesting immune response modulation for the Th2 profile. The histopathological analysis showed significant morphological alterations, compatible with acute pulmonary lesions, with polymorphonuclear leukocyte (PMN) infiltration, intra-alveolar edema, congestion, hemorrhage and atelectasis. These findings advance our understanding of the dynamics of envenomation and contribute to improve clinical management and antiophidic therapy for individuals exposed to venom.

Edema Induced by a Crotalus durissus terrificus Venom Serine Protease (Cdtsp 2) Involves the PAR Pathway and PKC and PLC Activation

Snake venom serine proteases (SVSPs) represent an essential group of enzymatic toxins involved in several pathophysiological effects on blood homeostasis. Some findings suggest the involvement of this class of enzymatic toxins in inflammation. In this paper, we purified and isolated a new gyroxin isoform from the Crotalus durissus terrificus (Cdt) venom, designated as Cdtsp 2, which showed significant proinflammatory effects in a murine model. In addition, we performed several studies to elucidate the main pathway underlying the edematogenic effect induced by Cdtsp 2. Enzymatic assays and structural analysis (primary structure analysis and three-dimensional modeling) were closely performed with pharmacological assays. The determination of edematogenic activity was performed using Cdtsp 2 isolated from snake venom, and was applied to mice treated with protein kinase C (PKC) inhibitor, phospholipase C (PLC) inhibitor, dexamethasone (Dexa), antagonists for protease-activated receptors (PARs), or saline (negative control). Additionally, we measured the levels of cyclooxygenase 2 (COX-2), malondialdehyde (MDA), and prostaglandin E2 (PGE2). Cdtsp 2 is characterized by an approximate molecular mass of 27 kDa, an isoelectric point (pI) of 4.5, and significant fibrinolytic activity, as well as the ability to hydrolyze Nα-benzoyl-l-arginine 4-nitroanilide (BAPNA). Its primary and three-dimensional structures revealed Cdtsp 2 as a typical snake venom serine protease that induces significant edema via the metabolism of arachidonic acid (AA), involving PARs, PKC, PLC, and COX-2 receptors, as well as inducing a significant increase in MDA levels. Our results showed that Cdtsp 2 is a serine protease with significant enzymatic activity, and it may be involved in the degradation of PAR1 and PAR2, which activate PLC and PKC to mobilize AA, while increasing oxidative stress. In this article, we provide a new perspective for the role of SVSPs beyond their effects on blood homeostasis.

Mechanistic insights into functional characteristics of native crotamine

The chemical composition of snake venoms is a complex mixture of proteins and peptides that can be pharmacologically active. Crotamine, a cell-penetrating peptide, has been described to have antimicrobial properties and it exerts its effects by interacting selectively with different structures, inducing changes in the ion flow pattern and cellular responses. However, its real therapeutic potential is not yet fully known. Bearing in mind that crotamine is a promising molecule in therapeutics, this study investigated the action of purified molecule in three aspects: I) antibacterial action on different species of clinical interest, II) the effect of two different concentrations of the molecule on platelet aggregation, and III) its effects on isolated mitochondria. Crotamine was purified to homogeneity in a single step procedure using Heparin Sepharose. The molecular mass of the purified enzyme was 4881.4 Da, as determined by mass spectrometry. To assess antibacterial action, changes in the parameters of bacterial oxidative stress were determined. The peptide showed antibacterial activity on Escherichia coli (MIC: 2.0 μg/μL), Staphylococcus aureus (MIC: 8-16 μg/μL) and methicillin-resistant Staphylococcus aureus (MIC: 4.0-8.0 μg/μL), inducing bacterial death by lipid peroxidation and oxidation of target proteins, determined by thiobarbituric acid reactive substances and sulfhydryl groups, respectively. Crotamine induced increased platelet aggregation (IPA) at the two concentrations analyzed (0.1 and 1.4 μg/μL) compared to ADP-induced aggregation of PRP. Mitochondrial respiratory parameters and organelle structure assays were used to elucidate the action of the compound in this organelle. The exposure of mitochondria to crotamine caused a decrease in oxidative phosphorylation and changes in mitochondrial permeability, without causing damage in the mitochondrial redox state. Together, these results support the hypothesis that, besides the antimicrobial potential, crotamine acts on different molecular targets, inducing platelet aggregation and mitochondrial dysfunction.

Pulmonary mechanic and lung histology induced by Crotalus durissus cascavella snake venom

This study have analyzed the pulmonary function in an experimental model of acute lung injury, induced by the Crotalus durissus cascavella venom (C. d. cascavella) (3.0 μg/kg - i.p), in pulmonary mechanic and histology at 1 h, 3 h, 6 h, 12 h and 24 h after inoculation. The C. d. cascavella venom led to an increase in Newtonian Resistance (R_N), Tissue Resistance (G) and Tissue Elastance (H) in all groups when compared to the control, particularly at 12 h and 24 h. The Histeresivity (η) increased 6 h, 12 h and 24 h after inoculation. There was a decrease in Static Compliance (C_ST) at 6 h, 12 h and 24 h and inspiratory capacity (IC) at 3 h, 6 h, 12 h and 24 h. C. d. cascavella venom showed significant morphological changes such as atelectasis, emphysema, hemorrhage, polymorphonuclear inflammatory infiltrate, edema and congestion. After a challenge with methacholine (MCh), R_N demonstrated significant changes at 6, 12 and 24 h. This venom caused mechanical and histopathological changes in the lung tissue; however, its mechanisms of action need further studies in order to better elucidate the morphofunctional lesions.

Biochemical and biological characterization of two serine proteinases from Colombian Crotalus durissus cumanensis snake venom

Two clotting serine proteinases, named Cdc SI and Cdc SII, were isolated and characterized for the first time from Colombian Crotalus durissus cumanensis snake venom. The enzymes were purified using two chromatographic steps: molecular exclusion on Sephacryl S-200 and RP-HPLC on C8 Column. The molecular masses of the proteins, determined by MALDI-TOF mass spectrometry, were 28,561.4 and 28,799.2 Da for Cdc SI and Cdc SII, respectively. The aim of the present study was to evaluate enzymatic, coagulant and toxic properties of the two enzymes. The serine proteinases hydrolyzed specific chromogenic substrate (BaPNA) and exhibited a Michaelis-Menten behavior. Cdc SI had V(max) of 0.038 ± 0.003 nmol/min and K(M) of 0.034 ± 0.017 mM, while Cdc SII displayed values of V(max) of 0.267 ± 0.011 nmol/min and K(M) of 0.145 ± 0.023 mM. N-terminal sequences were VIGGDEXNIN and VIGGDICNINEHNFLVALYE for Cdc SI and Cdc SII, respectively. Molecular masses, N-terminal sequences, inhibition assays, and enzymatic profile suggest that Cdc SI and Cdc SII belong to the family of snake venom thrombin-like enzymes. These serine proteinases differed in their clotting activity on human plasma, showing a minimum coagulant dose of 25 μg and 0.571 μg for Cdc SI and Cdc SII, respectively. Enzymes also showed coagulant activity on bovine fibrinogen and degraded chain α of this protein. Toxins lack hemorrhagic and myotoxic activities, but are capable to induce defibrin(ogen)ation, moderate edema, and an increase in vascular permeability. These serine proteinases may contribute indirectly to the local hemorrhage induced by metalloproteinases, by causing blood clotting disturbances, and might also contribute to cardiovascular alterations characteristic of patients envenomed by C. d. cumanensis in Colombia.

Effects of low molecular weight sulfated galactan fragments from Botryocladia occidentalis on the pharmacological and enzymatic activity of sPLA2 from Crotalus durissus cascavella

Low molecular weight fragments of sulfated galactans (Boc-5 and Boc-10) from the red algae Botryocladia occidentalis significantly inhibited Crotalus durissus cascavella sPLA2 enzymatic activity. Equimolar ratios of sPLA2 to Boc-5 or Boc-10 resulted in allosteric inhibition of sPLA2. Under the conditions tested, we observed that both Boc-5 and Boc-10 strongly decreased edema, myonecrosis, and neurotoxicity induced by native sPLA2.

Modulation of the pharmacological activities of secretory phospholipase A2 from Crotalus durissus cascavella induced by naringin

In this work we have characterized the action of the naringin, a flavonoid found in grapefruit and known for its various pharmacological effects, which include antioxidant blood lipid lowering and anticancer activity, on the structure and biochemical activities of a secretory phospholipase A (sPLA2) from Crotalus durissus cascavella, an important protein involved in the releasinge of arachidonic acid in phospholipid membranes. sPLA2 was incubated with naringin (mol:mol) at 37 °C and a discrete reduction in the UV scanning signal and a modification of the circular dichroism spectra were observed after treatment with naringin, suggesting modifications of the secondary structure of the protein. This flavonoid was able to decrease enzymatic activity and some pharmacological effects, such as myonecrosis, platelet aggregation, and neurotoxic activity caused by sPLA2, however, the inflammatory effect was not affected by naringin. In addition, small angle X-ray scattering (SAXS) data were collected for sPLA2 and naringin-treated sPLA2 to evaluate possible modifications of the protein structure. These structural investigations have shown that sPLA2 is an elongated dimer in solution and after treatment with naringin a conformational change in the dimeric configuration was observed. Our results suggest that structural modification may be correlated with the loss of enzymatic activity and alterations in pharmacological properties.

Effect of the synthetic coumarin, ethyl 2-oxo-2H-chromene-3-carboxylate, on activity of Crotalus durissus ruruima sPLA2 as well as on edema and platelet aggregation induced by this factor

We show that ethyl 2-oxo-2H-chromene-3-carboxylate (EOCC), a synthetic coumarin, irreversibly inhibits phospholipase A(2) (sPLA2) from Crotalus durissus ruruima venom (sPLA2r) with an IC(50) of 3.1 +/- 0.06 nmol. EOCC strongly decreased the V(max) and K(m), and it virtually abolished the enzyme activity of sPLA2r as well as sPLA2s from other sources. The edema induced by sPLA2r + EOCC was less than that induced by sPLA2r treated with p-bromophenacyl bromide, which was more efficient at neutralizing the platelet aggregation activity of native sPLA2r. Native sPLA2r induced platelet aggregation of 91.54 +/- 9.3%, and sPLA2r + EOCC induced a platelet aggregation of 18.56 +/- 6.5%. EOCC treatment also decreased the myotoxic effect of sPLA2r. Mass spectrometry showed that EOCC formed a stable complex with sPLA2r, which increased the mass of native sPLA2r from 14,299.34 Da to 14,736.22 Da. Moreover, the formation of this complex appeared to be involved in the loss of sPLA2r activity. Our results strongly suggest that EOCC can be used as a pharmacological agent against the sPLA2 in Crotalus durissus sp. venom as well as other sPLA2s.

Purification and characterization of the biological effects of phospholipase A(2) from sea anemone Bunodosoma caissarum

Sea anemones contain a variety of biologically active substances. Bunodosoma caissarum is a sea anemone from the Cnidaria phylum, found only in Brazilian coastal waters. The aim of the present work was to study the biological effects of PLA(2) isolated from the sea anemone B. caissarum on the isolated perfused kidney, the arteriolar mesenteric bed and on insulin secretion. Specimens of B. caissarum were collected from the São Vicente Channel on the southern coast of the State of São Paulo, Brazil. Reverse phase HPLC analysis of the crude extract of B. caissarum detected three PLA(2) proteins (named BcPLA(2)1, BcPLA(2)2 and BcPLA(2)3) found to be active in B. caissarum extracts. MALDI-TOF mass spectrometry of BcPLA(2)1 showed one main peak at 14.7 kDa. The N-terminal amino acid sequence of BcPLA(2)1 showed high amino acid sequence identity with PLA(2) group III protein isolated from the Mexican lizard (PA23 HELSU, HELSU, PA22 HELSU) and with the honey bee Apis mellifera (PLA(2) and 1POC_A). In addition, BcPLA(2)1 also showed significant overall homology to bee PLA(2). The enzymatic activity induced by native BcPLA(2)1 (20 microg/well) was reduced by chemical treatment with p-bromophenacyl bromide (p-BPB) and with morin. BcPLA(2)1 strongly induced insulin secretion in presence of high glucose concentration. In isolated kidney, the PLA(2) from B. caissarum increased the perfusion pressure, renal vascular resistance, urinary flow, glomerular filtration rate, and sodium, potassium and chloride levels of excretion. BcPLA(2)1, however, did not increase the perfusion pressure on the mesenteric vascular bed. In conclusion, PLA(2), a group III phospholipase isolated from the sea anemone B. caissarum, exerted effects on renal function and induced insulin secretion in conditions of high glucose concentration.

Purification and preliminary crystallographic analysis of a new Lys49-PLA2 from B. Jararacussu

BjVIII is a new myotoxic Lys49-PLA2 isolated from Bothrops jararacussu venom that exhibits atypical effects on human platelet aggregation. To better understand the mode of action of BjVIII, crystallographic studies were initiated. Two crystal forms were obtained, both containing two molecules in the asymmetric unit (ASU). Synchrotron radiation diffraction data were collected to 2.0 A resolution and 1.9 A resolution for crystals belonging to the space group P2(1)2(1)2(1) (a = 48.4 A, b = 65.3 A, c = 84.3 A) and space group P3(1)21 (a = b = 55.7 A, c = 127.9 A), respectively. Refinement is currently in progress and the refined structures are expected to shed light on the unusual platelet aggregation activity observed for BjVIII.

Purification and biological effects of L-amino acid oxidase isolated from Bothrops insularis venom

Bothrops insularis is a snake from Ilha da Queimada Grande, an island located about 20 miles away from the Southeastern coast of Brazil. Compared with other Brazilian species of Bothrops, the toxinology of B. insularis is still poorly understood, and so far, no fraction from this venom with amino acid oxidase activity had been isolated or its biological activity tested. We investigated the biochemical and biological effects of one l-amino acid oxidase enzyme isolated from B. insularis snake venom (BiLAO), which was purified using HPLC and sequence grade. We also evaluated the renal effects induced by BiLAO. Chromatographic profile of B. insularis whole venom disclosed seven main fractions (I, II, III, IV, V, VI and VII) and the main LAO enzymatic activity was detected in fraction II. The group treated with BiLAO showed a decrease in perfusion pressure (C(120)=110.28+/-3.69; BiLAO(120)=82.2+/-5.6 mmHg*); renal vascular resistance (C(120)=5.48+/-0.53; BiLAO(120)=4.12+/-0.42 mmHg/mL/g/min*), urinary flow (C(120)=0.160+/-0.020; BiLAO(120)=0.064+/-0.012 mL/g/min*), glomerular filtration rate (C(120)=0.697+/-0.084; BiLAO(120)=0.176+/-0.017 mL/g/min*), sodium (C(120)=79.76+/-0.56; BiLAO(120)=65.39+/-6.19%*), potassium (C(120)=69.94+/-6.86; BiLAO(120)=60.26+/-2.24%*) and chloride tubular reabsortion (C(120)=78.53+/-2.33; BiLAO(120)=64.58+/-6.68%*). Acute tubular necrosis foci were observed in the group treated with the LAO fraction of the B. insularis snake venom. Some findings have the same morphological aspect of apoptosis, more evident cortically; otherwise, reversible degenerative phenomena represented by hydropic ballooning with extensive cytoplasmic vacuolization and discontinuity of the cell brush borders in the proximal tubular epithelium were observed; furthermore, necrotic detachment of these cells into the tubular lumina, and increased amount of protein deposits in the distal and proximal tubules were observed. In conclusion, the slowness of blood flow and of glomerular filtration resulted in more time for filtration and tubular reabsorption, with elevation of the total percentage of sodium and chlorine reabsorption. The maintenance of the decrease in glomerular filtration rate would determine the subsequent decreases, which were noticed in these parameters. The necrosis observed was the result of damage cell induced by l-amino acid oxidase isolated from B. insularis venom.