A novel pentameric phospholipase A2 myotoxin (PophPLA2) from the venom of the pit viper Porthidium ophryomegas

Antioxidant and Neuroprotective Effects of the First Tryptophyllin Found in Snake Venom (Bothrops moojeni)

In this study, we report the isolation, characterization, and synthesis of the peptide BmT-2 belonging to the tryptophyllins family, isolated from the venom of the snake Bothrops moojeni. This is the first time a tryptophyllin is identified in snake venom. We tested whether BmT-2 had cytotoxic effects and antioxidant activity in a set of experiments that included both in vitro and cell-based assays. BmT-2 presented a radical scavenging activity toward ABTS^• and AAPH-derived radicals. BmT-2 protected fluorescein, DNA molecules, and human red blood cells (RBCs) from free radicals generated by the thermal decomposition of AAPH. The novel tryptophyllin was not toxic in cell viability tests, where it (up to 0.4 mg/mL) did not cause hemolysis of human RBCs and did not cause significant loss of cell viability, showing a CC₅₀ > 1.5 mM for cytotoxic effects against SK-N-BE(2) neuroblastoma cells. BmT-2 prevented the arsenite-induced upregulation of Nrf2 in Neuro-2a neuroblasts and the phorbol myristate acetate-induced overgeneration of reactive oxygen species and reactive nitrogen species in SK-N-BE(2) neuroblastoma cells. Electronic structure calculations and full atomistic reactive molecular dynamics simulations revealed the relevant contribution of aromatic residues in BmT-2 to its antioxidant properties. Our study presents a novel peptide classified into the family of the tryptophyllins, which has been reported exclusively in amphibians. Despite the promising results on its antioxidant activity and low cytotoxicity, the mechanisms of action of BmT-2 still need to be further elucidated.

Venomics of the poorly studied hognosed pitvipers Porthidium arcosae and Porthidium volcanicum

We report the first proteomics analyses of the venoms of two poorly studied snakes, the Manabi hognosed pitviper Porthidium arcosae endemic to the western coastal province of Manabí (Ecuador), and the Costa Rican hognosed pitviper P. volcanicum with distribution restricted to South Pacific Costa Rica and western Panamá. These venom proteomes share a conserved compositional pattern reported in four other congeneric species within the clade of South American Porthidium species, P. nasutum, P. lansbergii, P. ophryomegas, and P. porrasi. The paraspecific immunorecognition profile of antivenoms produced in Costa Rica (ICP polyvalent), Perú (Instituto Nacional de Salud) and Brazil (soro antibotrópico pentavalente, SAB, from Instituto Butantan) against the venom of P. arcosae was investigated through a third-generation antivenomics approach. The maximal venom-binding capacities of the investigated antivenoms were 97.1 mg, 21.8 mg, and 25.7 mg of P. arcosae venom proteins per gram of SAB, ICP, and INS-PERU antibody molecules, respectively, which translate into 28.4 mg, 13.1 mg, and 15.2 mg of total venom proteins bound per vial of SAB, ICP, and INS-PERU AV. The antivenomics results suggest that 21.8%, 7.8% and 6.1% of the SAB, ICP, and INS-PERU antibody molecules recognized P. arcosae venom toxins. The SAB antivenom neutralized P. arcosae venom's lethality in mice with an ED₅₀ of 31.3 mgV/g SAB AV. This preclinical neutralization paraspecificity points to Brazilian SAB as a promising candidate for the treatment of envenomings by Ecuadorian P. arcosae. BIOLOGICAL SIGNIFICANCE: Assessing the preclinical efficacy profile of antivenoms against homologous and heterologous medically relevant snake venoms represents an important goal towards defining the biogeographic range of their clinical utility. This is particularly relevant in regions, such as Mesoamerica, where a small number of pharmaceutical companies produce antivenoms against the venoms of a small number of species of maximum medical relevance among the local rich herpetofauna, leaving a wide range of snakes of secondary medical relevance, but also causing life-threatening human envenomings without nominal clinical coverage. This work is part of a larger project aiming at mapping the immunological characteristics of antivenoms generated in Latin American countries towards venoms of such poorly studied snakes of the local and neighboring countries' herpetofauna. Here we report the proteomics characterization of the Manabi hognosed pitviper Porthidium arcosae endemic to the western coastal province of Manabí (Ecuador), and the Costa Rican hognosed pitviper P. volcanicum with distribution restricted to southwestern Costa Rica, the antivenomics assessment of three bothropoid commercial antivenoms produced in Costa Rica, Perú, and Brazil against the venom components of P. arcosae, and the in vivo capacity of the Brazilian soro antibotrópico pentavalente (SAB) from Instituto Butantan to neutralize the murine lethality of P. arcosae venom. The preclinical paraspecific ED₅₀ of 31.3 mg of P. arcosae venom per gram of antivenom points to Brazilian SAB as a promising candidate for the treatment of envenomings by the Manabi hognosed pitviper P. arcosae.

Molecular cloning and characterization of the two putative toxins expressed in the venom of the devil stinger Inimicus japonicus

Various proteins are involved in fish venom toxicity, but limited information is available regarding their structure and mode of action. Here, we analyzed RNA transcripts in the dorsal spine of the devil stinger Inimicus japonicus using next-generation sequencing (NGS), and identified two putative protein toxins, a natterin-like protein (Ij-natterin) and a phospholipase A₂ (Ij-PLA₂), as well as a previously reported stonustoxin-like protein. The deduced amino acid sequence of Ij-natterin suggested that it acts as a pore-forming toxin through the cooperation of the N-terminal lectin-like domain and the C-terminal pore-forming domain. Ij-PLA₂ showed significant homology with secreted Ca²⁺-dependent PLA₂s from snake venom and mammals (sPLA₂-I/II). The recombinant Ij-PLA₂ protein exhibited PLA₂ activity in the absence of Ca²⁺, in contrast to canonical sPLA₂-I/II. Comparison of the amino acid sequences of Ij-PLA₂ with the other sPLA₂-I/II suggests that the C-terminal extended peptide region of Ij-PLA₂ is involved in its Ca²⁺-independent activity.

Structural, enzymatic and pharmacological profiles of AplTX-II - A basic sPLA2 (D49) isolated from the Agkistrodon piscivorus leucostoma snake venom

A basic sPLA₂ (D49) from the venom of snake Agkistrodon piscivorus leucostoma (AplTX-II) was isolated, purified and characterized. We determined the enzymatic and pharmacological profiles of this toxin. AplTX-II was isolated with a high level of purity through reverse phase chromatography and molecular exclusion. The enzyme showed pI 9.48 and molecular weight of 14,003 Da. The enzymatic activity of the AplTX-II depended on Ca²⁺ pH and temperature. The comparison of the primary structure with other sPLA₂s revealed that AplTX-II presented all the structural reasons expected for a basic sPLA₂s. Additionally, we have resolved its structure with the docked synthetic substrate NOBA (4-nitro-3-octanoyloxy benzoic acid) by homology modeling, and performed MD simulations with explicit solvent. Structural similarities were found between the enzyme's modeled structure and other snake sPLA₂ X-Ray structures, available in the PDB database. NOBA and active-site water molecules spontaneously adopted stable positions and established interactions in full agreement with the reaction mechanism, proposed for the physiological substrate, suggesting that NOBA hydrolysis is an excellent model to study phospholipid hydrolysis.

Antibiofilm Activity of Acidic Phospholipase Isoform Isolated from Bothrops erythromelas Snake Venom

Introduction: Bacterial resistance is a worldwide public health problem, requiring new therapeutic options. An alternative approach to this problem is the use of animal toxins isolated from snake venom, such as phospholipases A₂ (PLA₂), which have important antimicrobial activities. Bothropserythromelas is one of the snake species in the northeast of Brazil that attracts great medical-scientific interest. Here, we aimed to purify and characterize a PLA₂ from B. erythromelas, searching for heterologous activities against bacterial biofilms. Methods: Venom extraction and quantification were followed by reverse-phase high-performance liquid chromatography (RP-HPLC) in C18 column, matrix-assisted ionization time-of-flight (MALDI-ToF) mass spectrometry, and sequencing by Edman degradation. All experiments were monitored by specific activity using a 4-nitro-3-(octanoyloxy) benzoic acid (4N₃OBA) substrate. In addition, hemolytic tests and antibacterial tests including action against Escherichiacoli, Staphylococcusaureus, and Acinetobacterbaumannii were carried out. Moreover, tests of antibiofilm action against A. baumannii were also performed. Results: PLA₂, after one purification step, presented 31 N-terminal amino acid residues and a molecular weight of 13.6564 Da, with enzymatic activity confirmed in 0.06 µM concentration. Antibacterial activity against S. aureus (IC₅₀ = 30.2 µM) and antibiofilm activity against A. baumannii (IC₅₀ = 1.1 µM) were observed. Conclusions: This is the first time that PLA₂ purified from B. erythromelas venom has appeared as an alternative candidate in studies of new antibacterial medicines.

The effect of different cross-linking conditions of EDC/NHS on type II collagen scaffolds: an in vitro evaluation

The purpose of this paper is to analyze the properties of porcine cartilage type II collagen scaffolds crosslinked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxy-succinamide (EDC/NHS) under different conditions. The porous EDC/NHS-crosslinked scaffolds were obtained through a two-step freeze-drying process. To determine the optimal crosslinking condition, we used different solvents and various crosslinking temperatures to prepare the scaffolds. Three crosslinking solutions were prepared with different solvents, photographs were taken with a flash in the darkroom, and light transmission was observed. Type II collagen was crosslinked on a horizontal shaker at a speed of 60 r/min according to the above grouping conditions, and then the structural change of the scaffold in each group was observed. To investigate the swelling ratio and the in vitro degradation of the collagen scaffold, tests were also carried out by immersion of the scaffolds in a PBS solution and digestion in type II collagenase, respectively. The influence of the scaffolds on the proliferation of chondrocytes was assessed by the methyl thiazolyl tetrazolium colorimetric assay. The morphology of the crosslinked scaffolds cocultured with chondrocytes was characterized by a scanning electron microscope. The results proved that 75% alcohol and a crosslinking temperature of 37 °C are recommended. Collagen fibrils are more densely packed after crosslinking with EDC/NHS and have a more uniform structure than that of noncrosslinked ones. The EDC-crosslinked scaffolds possessed excellent mechanical property and biocompatibility.

Proteomic profiling, functional characterization, and immunoneutralization of the venom of Porthidium porrasi, a pitviper endemic to Costa Rica

The genus Porthidium includes nine pitviper species inhabiting Mexico, Central America, and northern South America. Porthidium porrasi is a species endemic to the Southwest of Costa Rica, for which no information on its venom was available. In this study, the proteomic composition and functional activities of P. porrasi venom are described. The most abundant venom proteins were identified as metalloproteinases (36.5%). In descending order of abundance, proteins belonging to the disintegrin, phospholipase A₂, serine proteinase, C-type lectin/lectin-like, vascular endothelial growth factor, Cysteine-rich secretory protein, L-amino acid oxidase, phospholipase B, and phosphodiesterase families were also identified. P. porrasi venom showed a weak lethal potency in mice (10 μg/g body weight by intraperitoneal route), induced marked hemorrhage and edema, and weak myotoxic effect. These in vivo activities, as well as those assayed in vitro (proteolytic and phospholipase A₂ activities) correlated with compositional data. A comparison of P. porrasi venom with those of three other Porthidium species studied to date reveals a generally conserved compositional and functional pattern in this pitviper genus. Importantly, the lethal effect of P. porrasi venom in mice was adequately cross-neutralized by a heterospecific polyvalent antivenom, supporting its use in the treatment of eventual envenomings by this species.