Unmasking snake venom of Bothrops leucurus: purification and pharmacological and structural characterization of new PLA2 Bleu TX-III

Effect of combined red and infrared wavelengths on inflammation, hemorrhage, and muscle damage caused by Bothrops leucurus snake venom

To evaluate the effects of red and infrared wavelengths, separately and combined, on the inflammatory process and collagen deposition in muscle damage caused by B. leucurus venom. 112 mice were inoculated with diluted venom (0.6mg/kg) in the gastrocnemius muscle. The animals were divided into four groups: one control (CG) and three treatments, namely: 1) red laser (λ=660 nm) (RG), 2) infrared laser (λ=808 nm) (IG) and 3) red laser (λ=660 nm) + infrared (λ=808 nm) (RIG). Each group was subdivided into four subgroups, according to the duration of treatment application (applications every 24 hours over evaluation times of up to 144 hours). A diode laser was used (0.1 W, CW, 1J/point, ED: 10 J/cm2). Both wavelengths reduced the intensity of inflammation and the combination between them significantly intensified the anti-inflammatory response. Photobiomodulation also changed the type of inflammatory infiltrate observed and RIG had the highest percentage of mononuclear cells in relation to the other groups. Hemorrhage intensity was significantly lower in treated animals and RIG had the highest number of individuals in which this variable was classified as mild. As for collagen deposition, there was a significant increase in RG in relation to CG, in RIG in relation to CG and in RIG in relation to IG. Photobiomodulation proved to be effective in the treatment of inflammation and hemorrhage caused by B. leucurus venom and stimulated collagen deposition. Better results were obtained with the combined wavelengths.

Hybridization between Crotalus aquilus and Crotalus polystictus Species: A Comparison of Their Venom Toxicity and Enzymatic Activities

Hybridization is defined as the interbreeding of individuals from two populations distinguishable by one or more heritable characteristics. Snake hybridization represents an interesting opportunity to analyze variability and how genetics affect the venom components between parents and hybrids. Snake venoms exhibit a high degree of variability related to biological and biogeographical factors. The aim of this work is to analyze the protein patterns and enzymatic activity of some of the main hemotoxic enzymes in snake venoms, such as serine proteases (trypsin-like, chymotrypsin-like, and elastase-like), metalloproteases, hyaluronidases, and phospholipase A₂. The lethal dose of 50 (LD₅₀) of venom from the Crotalus aquilus (Cabf) and Crotalus polystictus (Cpbm) parents and their hybrids in captivity was determined, and phenetic analysis is also conducted, which showed a high similarity between the hybrids and C. polystictus. The protein banding patterns and enzymatic activity analyze by zymography resulted in a combination of proteins from the parental venoms in the hybrids, with variability among them. In some cases, the enzymatic activity is higher in the hybrids with a lower LD₅₀ than in the parents, indicating higher toxicity. These data show the variability among snake venoms and suggest that hybridization is an important factor in changes in protein concentration, peptide variability, and enzymatic activity that affect toxicity and lethality.

Edema, hyperalgesia and myonecrosis induced by Brazilian bothropic venoms: overview of the last decade

Snakebite accidents are considered serious public health problems. They are often neglected, and individuals who have received insufficient treatment are subjected to various disabling alterations. Snake venoms are secretions composed of biologically active molecules capable of triggering local and systemic effects in envenomation victims. Bothropic snakes are responsible for most of the ophidian accidents in Brazil; their venoms are mainly related to local manifestations, due to a composition that is especially rich in proteases and phospholipases A₂. The most common local damages are inflammation, with consequent cellular activation and release of inflammatory mediators, hemorrhage, edema, pain and (myo)necrosis, which may lead to amputation of the affected areas. Antivenom therapy is the main treatment for snakebites. However, the efficiency is mainly due to the neutralization of the toxins responsible for the systemic alterations. Thus, the local damages can evolve to markedly compromise the tissue. The complexity of these local effects associated with the toxicity of the snake venom components of the genus Bothrops, arouse interest in the study of the biochemical and pathophysiological mechanisms involved with the actions caused by toxins of the venom. Therefore, this review aims to analyze the edematogenic, hyperalgesic and myotoxic effects caused by Brazilian bothropic venoms in order to contribute to the study and elucidation of the mechanisms of action of its components and, consequently, enable discoveries of more effective combined therapies in the treatment of local damages resulting from envenoming.

ACP-TX-I and ACP-TX-II, Two Novel Phospholipases A2 Isolated from Trans-Pecos Copperhead Agkistrodon contortrix pictigaster Venom: Biochemical and Functional Characterization

This work reports the purification and biochemical and functional characterization of ACP-TX-I and ACP-TX-II, two phospholipases A₂ (PLA₂) from Agkistrodon contortrix pictigaster venom. Both PLA₂s were highly purified by a single chromatographic step on a C₁₈ reverse phase HPLC column. Various peptide sequences from these two toxins showed similarity to those of other PLA₂ toxins from viperid snake venoms. ACP-TX-I belongs to the catalytically inactive K49 PLA₂ class, while ACP-TX-II is a D49 PLA₂, and is enzymatically active. ACP-TX-I PLA₂ is monomeric, which results in markedly diminished myotoxic and inflammatory activities when compared with dimeric K49 PLA₂s, confirming the hypothesis that dimeric structure contributes heavily to the profound myotoxicity of the most active viperid K49 PLA₂s. ACP-TX-II exhibits the main pharmacological actions reported for this protein family, including in vivo local myotoxicity, edema-forming activity, and in vitro cytotoxicity. ACP-TX-I PLA₂ is cytotoxic to A549 lung carcinoma cells, indicating that cytotoxicity to these tumor cells does not require enzymatic activity.

Snake Venom Hemotoxic Enzymes: Biochemical Comparison between Crotalus Species from Central Mexico

Snakebite envenoming is a serious medical problem in different areas of the world. In Latin America, the major prevalence is due to snakes of the family Viperidae, where rattlesnakes (Crotalus) are included. They produce hemotoxic venom which causes bleeding, tissue degradation and necrosis. Each venom has several enzymatic activities, producing different effects in the envenoming, doing its clinical effects difficult to study. Comparison between venom molecules is also difficult when different techniques are used, and therefore, their identification/characterization using the same methodology is necessary. In this work, a general biochemical characterization in snake venom of serine proteases (SVSP), phospholipases A₂ (PLA₂), metalloproteases (SVMP) and hyaluronidases (SVH) of Crotalus aquilus (Ca), Crotalus polystictus (Cp) and Crotalus molossus nigrescens (Cmn) was done. Differences in protein pattern, enzyme content and enzymatic activities were observed. All the venoms showed high PLA₂ activity, high molecular weight SVSP, and a wide variety of SVMP and SVH forms. Ca and Cp showed the highest enzymatic activities of SVMP and SVSP trypsin-like and chymotrypsin-like, whereas Cmn showed the highest SVH and similar PLA₂ activity with Ca. All the venoms showed peptides with similar molecular weight to crotamine-like myotoxins. No previous biochemical characterization of C. aquilus has been reported and there are no previous analyses that include these four protein families in these Crotalus venoms.

Cytotoxic and inflammatory potential of a phospholipase A2 from Bothrops jararaca snake venom

Background

Snake venom phospholipases A₂ (PLA₂s) have been reported to induce myotoxic, neurotoxic, hemolytic, edematogenic, cytotoxic and proinflammatory effects. This work aimed at the isolation and functional characterization of a PLA₂ isolated from Bothrops jararaca venom, named BJ-PLA₂-I.

Methods and Results

For its purification, three consecutive chromatographic steps were used (Sephacryl S-200, Source 15Q and Mono Q 5/50 GL). BJ-PLA₂-I showed acidic characteristics, with pI~ 4.4 and molecular mass of 14.2 kDa. Sequencing resulted in 60 amino acid residues that showed high similarity to other Bothrops PLA₂s, including 100% identity with BJ-PLA₂, an Asp49 PLA₂ previously isolated from B. jararaca venom. Being an Asp49 PLA₂, BJ-PLA₂-I showed high catalytic activity, and also inhibitory effects on the ADP-induced platelet aggregation. Its inflammatory characterization showed that BJ-PLA₂-I was able to promote leukocyte migration in mice at different concentrations (5, 10 and 20 μg/mL) and also at different response periods (2, 4 and 24 h), mainly by stimulating neutrophil infiltration. Furthermore, increased levels of total proteins, IL-6, IL-1β and PGE₂ were observed in the inflammatory exudate induced by BJ-PLA₂-I, while nitric oxide, TNF-α, IL-10 and LTB₄ levels were not significantly altered. This toxin was also evaluated for its cytotoxic potential on normal (PBMC) and tumor cell lines (HL-60 and HepG2). Overall, BJ-PLA₂-I (2.5–160 μg/mL) promoted low cytotoxicity, with cell viabilities mostly varying between 70 and 80% and significant values obtained for HL-60 and PBMC only at the highest concentrations of the toxin evaluated.

Conclusions

BJ-PLA₂-I was characterized as an acidic Asp49 PLA₂ that induces acute local inflammation and low cytotoxicity. These results should contribute to elucidate the action mechanisms of snake venom PLA₂s.

Immune cells and mediators involved in the inflammatory responses induced by a P-I metalloprotease and a phospholipase A2 from Bothrops atrox venom

Bothrops envenomations can promote severe inflammatory responses by inducing edema, pain, leukocyte recruitment and release of chemical mediators by local cells. In the present study, two toxins from Bothrops atrox venom (the P-I metalloprotease Batroxase and the acidic phospholipase A₂ BatroxPLA₂) were evaluated in relation to their inflammatory effects induced in vivo and in vitro, mainly focusing on the participation of different immune cells and inflammatory mediators. Both toxins mainly promoted acute inflammatory responses with significant recruitment of neutrophils in the early hours (1-4h) after administration into the peritoneal cavity of C57BL/6 mice, and increased infiltration of mononuclear cells especially after 24h. Among the mediators induced by both toxins are IL-6, IL-10 and PGE₂, with Batroxase also inducing the release of L-1β, and BatroxPLA₂ of LTB₄ and CysLTs. These responses pointed to possible involvement of immune cells such as macrophages and mast cells, which were then evaluated in vitro. Mice peritoneal macrophages stimulated with Batroxase produced significant levels of IL-6, IL-1β, PGE₂ and LTB₄, whereas stimulus with BatroxPLA₂ induced increases of IL-6, PGE₂ and LTB₄. Furthermore, both toxins were able to stimulate degranulation of RBL-2H3 mast cells, but with distinct concentration-dependent effects. Altogether, these results indicated that Batroxase and BatroxPLA₂ promoted local and acute inflammatory responses related to macrophages and mast cells and to the production of several mediators. Our findings should contribute for better understanding the different mechanisms of toxicity induced by P-I metalloproteases and phospholipases A₂ after snakebite envenomations.

Involvement of Nitric Oxide on Bothropoides insularis Venom Biological Effects on Murine Macrophages In Vitro

Viperidae venom has several local and systemic effects, such as pain, edema, inflammation, kidney failure and coagulopathy. Additionally, bothropic venom and its isolated components directly interfere on cellular metabolism, causing alterations such as cell death and proliferation. Inflammatory cells are particularly involved in pathological envenomation mechanisms due to their capacity of releasing many mediators, such as nitric oxide (NO). NO has many effects on cell viability and it is associated to the development of inflammation and tissue damage caused by Bothrops and Bothropoides venom. Bothropoides insularis is a snake found only in Queimada Grande Island, which has markedly toxic venom. Thus, the aim of this work was to evaluate the biological effects of Bothropoides insularis venom (BiV) on RAW 264.7 cells and assess NO involvement. The venom was submitted to colorimetric assays to identify the presence of some enzymatic components. We observed that BiV induced H2O2 production and showed proteolytic and phospholipasic activities. RAW 264.7 murine macrophages were incubated with different concentrations of BiV and then cell viability was assessed by MTT reduction assay after 2, 6, 12 and 24 hours of incubation. A time- and concentration-dependent effect was observed, with a tendency to cell proliferation at lower BiV concentrations and cell death at higher concentrations. The cytotoxic effect was confirmed after lactate dehydrogenase (LDH) measurement in the supernatant from the experimental groups. Flow cytometry analyses revealed that necrosis is the main cell death pathway caused by BiV. Also, BiV induced NO release. The inhibition of both proliferative and cytotoxic effects with L-NAME were demonstrated, indicating that NO is important for these effects. Finally, BiV induced an increase in iNOS expression. Altogether, these results demonstrate that B. insularis venom have proliferative and cytotoxic effects on macrophages, with necrosis participation. We also suggest that BiV acts by inducing iNOS expression and causing NO release.

PhTX-II a basic myotoxic phospholipase A₂ from Porthidium hyoprora snake venom, pharmacological characterization and amino acid sequence by mass spectrometry

A monomeric basic PLA₂ (PhTX-II) of 14149.08 Da molecular weight was purified to homogeneity from Porthidium hyoprora venom. Amino acid sequence by in tandem mass spectrometry revealed that PhTX-II belongs to Asp49 PLA₂ enzyme class and displays conserved domains as the catalytic network, Ca²⁺-binding loop and the hydrophobic channel of access to the catalytic site, reflected in the high catalytic activity displayed by the enzyme. Moreover, PhTX-II PLA₂ showed an allosteric behavior and its enzymatic activity was dependent on Ca²⁺. Examination of PhTX-II PLA₂ by CD spectroscopy indicated a high content of alpha-helical structures, similar to the known structure of secreted phospholipase IIA group suggesting a similar folding. PhTX-II PLA₂ causes neuromuscular blockade in avian neuromuscular preparations with a significant direct action on skeletal muscle function, as well as, induced local edema and myotoxicity, in mice. The treatment of PhTX-II by BPB resulted in complete loss of their catalytic activity that was accompanied by loss of their edematogenic effect. On the other hand, enzymatic activity of PhTX-II contributes to this neuromuscular blockade and local myotoxicity is dependent not only on enzymatic activity. These results show that PhTX-II is a myotoxic Asp49 PLA₂ that contributes with toxic actions caused by P. hyoprora venom.

Effect of chlorogenic acid (5-Caffeoylquinic Acid) isolated from Baccharis oxyodonta on the structure and pharmacological activities of secretory phospholipase A2 from Crotalus durissus terrificus

The aim of this paper was to investigate the effect of chlorogenic acid (5-caffeoylquinic acid, 5CQA), isolated from Baccharis oxyodonta, on the structure and pharmacological effect of secretory phospholipase A2 (sPLA2) from Crotalus durissus terrificus. All in vitro and in vivo experiments were conducted using a purified sPLA2 compared under the same experimental conditions with sPLA2 : 5CQA. 5CQA induced several discrete modifications in the secondary structure and the hydrophobic characteristics of native sPLA2 that induced slight changes in the α-helical content, increase in the random coil structure, and decrease of fluorescence of native sPLA2. Moreover, 5CQA significantly decreased the enzymatic activity and the oedema and myonecrosis induced by native sPLA2. As the catalytic activity of sPLA2 plays an important role in several of its biological and pharmacological properties, antibacterial activity was used to confirm the decrease in its enzymatic activity by 5CQA, which induced massive bacterial cell destruction. We found that 5CQA specifically abolished the enzymatic activity of sPLA2 and induced discrete protein unfolding that mainly involved the pharmacological site of sPLA2. These results showed the potential application of 5CQA in the snake poisoning treatment and modulation of the pathological effect of inflammation induced by secretory PLA2.

Abarema cochliacarpos extract decreases the inflammatory process and skeletal muscle injury induced by Bothrops leucurus venom

Snakebites are a public health problem, especially in tropical countries. However, treatment with antivenom has limited effectiveness against venoms' local effects. Here, we investigated the ability of Abarema cochliacarpos hydroethanolic extract (EAc) to protect mice against injection of Bothrops leucurus venom. Swiss mice received perimuscular venom injection and were subsequently treated orally with EAc in different doses. Treatment with EAc 100, 200, and 400 mg/kg reduced the edema induced by B. leucurus in 1%, 13%, and 39%, respectively. Although lower doses showed no antihypernociceptive effect in the Von Frey test, the higher dose significantly reduced hyperalgesia induced by the venom. Antimyotoxic activity of EAc was also observed by microscopy assessment, with treated muscles presenting preserved structures, decreased edema, and inflammatory infiltrate as compared to untreated ones. Finally, on the rotarod test, the treated mice showed better motor function, once muscle fibers were preserved and there were less edema and pain. Treated mice could stand four times more time on the rotating rod than untreated ones. Our results have shown that EAc presented relevant activities against injection of B. leucurus venom in mice, suggesting that it can be considered as an adjuvant in the treatment of envenomation.

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.