Antibacterial and antiparasitic effects of Bothrops marajoensis venom and its fractions: Phospholipase A2 and L-amino acid oxidase

Snake venom L-amino acid oxidases: trends in pharmacology and biochemistry

L-amino acid oxidases are enzymes found in several organisms, including venoms of snakes, where they contribute to the toxicity of ophidian envenomation. Their toxicity is primarily due to enzymatic activity, but other mechanisms have been proposed recently which require further investigation. L-amino acid oxidases exert biological and pharmacological effects, including actions on platelet aggregation and the induction of apoptosis, hemorrhage, and cytotoxicity. These proteins present a high biotechnological potential for the development of antimicrobial, antitumor, and antiprotozoan agents. This review provides an overview of the biochemical properties and pharmacological effects of snake venom L-amino acid oxidases, their structure/activity relationship, and supposed mechanisms of action described so far.

Volatile compounds of Lamiaceae exhibit a synergistic antibacterial activity with streptomycin

Bacterial infections cause thousands of deaths in the world every year. In most cases, infections are more serious because the patient is already weakened, and often, the bacteria are already resistant to the antibiotics used. Counterparting this negative scenario, the interest in medicinal plants as an alternative to the synthetic antimicrobial drugs is blossoming worldwide. In the present work, we identified the volatile compounds of ethanol extracts of Melissa officinalis, Mentha sp., Ocimum basilicum, Plectranthus barbatus, and Rosmarinus officinalis by gas chromatography/mass spectrometry (GC/MS). Also was evaluated antimicrobial activity of ethanol extracts against 6 bacteria of clinical interest, and was tested the interaction of these extracts with a commercial antibiotic streptomycin. Phytol was a compound identified in all extracts by GC/MS, being majoritary component in Plectranthus barbatus and Rosmarinus officinalis. The Gram-positive bacteria were more sensitive to ethanol extracts, and Plectranthus barbatus and Rosmarinus officinalis were the most active extracts. Ethanol extracts exhibited a synergetic effect with streptomycin. These results encourage additional studies, in order to evaluate the possibilities of using ethanol extracts of Lamiaceae family as natural source for antibacterial activity.

In vitro comparison of enzymatic effects among Brazilian Bothrops spp. venoms

In various types of snake venom, the major toxic components are proteinases and members of the phospholipase A2 family, although other enzymes also contribute to the toxicity. In this study, we evaluated the proteolytic, phospholipase, and L-Amino acid oxidase activities in the venom of five Bothrops species-Bothrops jararaca, Bothrops jararacussu, Bothrops moojeni, Bothrops neuwiedi, and Bothrops alternatus-all of which are used in the production of commercial antivenom, prepared in horses. The enzymatic activities of each species' venom were classified as high, moderate, or low. B. moojeni venom demonstrated the highest enzymatic activity profile, followed by the venom of B. neuwiedi, B. jararacussu, B. jararaca, and B. alternatus. To our knowledge, this is the first study to compare all of these enzymes from multiple species, which is significant in view of the activity of L-amino acid oxidase across Bothrops species.

BnSP-7 toxin, a basic phospholipase A2 from Bothrops pauloensis snake venom, interferes with proliferation, ultrastructure and infectivity of Leishmania (Leishmania) amazonensis

This paper reports the effects of BnSP-7 toxin, a catalytically inactive phospholipase A2 from Bothrops pauloensis snake venom, on Leishmania (Leishmania) amazonensis. BnSP-7 presented activity against promastigote parasite forms both in the MTT assay, with IC50 of 58·7 μg mL−1 of toxin, and a growth curve, inhibiting parasite proliferation 60–70% at concentrations of 50–200 μg mL−1 of toxin 96 h after treatment. Also, the toxin presented effects on amastigotes, reducing parasite viability by 50% at 28·1 μg mL−1 and delaying the amastigote–promastigote differentiation process. Ultrastructural studies showed that BnSP-7 caused severe morphological changes in promastigotes such as mitochondrial swelling, nuclear alteration, vacuolization, acidocalcisomes, multiflagellar aspects and a blebbing effect in the plasma membrane. Finally, BnSP-7 interfered with the infective capacity of promastigotes in murine peritoneal macrophages, causing statistically significant infectivity-index reductions (P < 0·05) of 20–35%. These data suggest that the BnSP-7 toxin is an important tool for the discovery of new parasite targets that can be exploited to develop new drugs for treating leishmaniasis.

Interactions of PLA2-s from Vipera lebetina, Vipera berus berus and Naja naja oxiana venom with platelets, bacterial and cancer cells

Secretory phospholipasesA₂ (sPLA₂s) form a large family of structurally related enzymes widespread in nature. Herein, we studied the inhibitory effects of sPLA₂s from Vipera lebetina (VLPLA₂), Vipera berus berus (VBBPLA₂), and Naja naja oxiana (NNOPLA₂) venoms on (i) human platelets, (ii) four different bacterial strains (gram-negative Escherichia coli and Vibrio fischeri; gram-positive Staphylococcus aureus and Bacillus subtilis) and (iii) five types of cancer cells (PC-3, LNCaP, MCF-7, K-562 and B16-F10) in vitro. sPLA₂s inhibited collagen-induced platelet aggregation: VBBPLA₂ IC₅₀ = 0.054, VLPLA₂ IC₅₀ = 0.072, NNOPLA₂ IC₅₀ = 0.814 μM. p-Bromophenacylbromide-inhibited sPLA₂ had no inhibitory action on platelets. 36.17 μM VBBPLA₂ completely inhibited the growth of gram-positive Bacillus subtilis whereas no growth inhibition was observed towards gram-negative Escherichia coli. The inhibitory action of sPLA₂s (~0.7 μM and ~7 μM) towards cancer cells depended on both venom and cell type. VBBPLA₂ (7.2 μM) inhibited significantly the viability of K-562 cells and the cell death appeared apoptotic. The sPLA₂s exhibited no inhibitory effect towards LNCaP cells and some effect (8%–20%) towards other cells. Thus, already sub-μM concentrations of sPLA₂s inhibited collagen-induced platelet aggregation and from the current suite of studied svPLA₂s and test cells, VBBPLA₂ was the most growth inhibitory towards Bacillus subtilis and K-562 cells.

In vitro antiplasmodial activity of phospholipases A2 and a phospholipase homologue isolated from the venom of the snake Bothrops asper

The antimicrobial and antiparasite activity of phospholipase A₂ (PLA₂) from snakes and bees has been extensively explored. We studied the antiplasmodial effect of the whole venom of the snake Bothrops asper and of two fractions purified by ion-exchange chromatography: one containing catalytically-active phospholipases A₂ (PLA₂) (fraction V) and another containing a PLA₂ homologue devoid of enzymatic activity (fraction VI). The antiplasmodial effect was assessed on in vitro cultures of Plasmodium falciparum. The whole venom of B. asper, as well as its fractions V and VI, were active against the parasite at 0.13 ± 0.01 µg/mL, 1.42 ± 0.56 µg/mL and 22.89 ± 1.22 µg/mL, respectively. Differences in the cytotoxic activity on peripheral blood mononuclear cells between the whole venom and fractions V and VI were observed, fraction V showing higher toxicity than total venom and fraction VI. Regarding toxicity in mice, the whole venom showed the highest lethal effect in comparison to fractions V and VI. These results suggest that B. asper PLA₂ and its homologue have antiplasmodial potential.

Antiplasmodial effect of the venom of Crotalus durissus cumanensis, crotoxin complex and Crotoxin B

The antiplasmodial activity of phospholipases A(2) (PLA(2)) isolated from different animals has been studied. We explored the in vitro anti Plasmodium falciparum effect of a fraction containing crotoxin, Crotoxin B and whole venom of the rattlesnake Crotalus durissus cumanensis. Fraction II (crotoxin complex) was obtained by size exclusion chromatography, whereas Crotoxin B was purified by RP-HPLC. The whole venom is active against the parasite at concentrations of 0.17±0.03 μg/ml, fraction II at 0.76±0.17 μg/ml and Crotoxin B at 0.6±0.04 μg/ml. Differences were observed in the cytotoxic activity against peripheral mononuclear cells, with Crotoxin B exhibiting the highest cytotoxicity. The concentration of Crotoxin B required to exert cytotoxic activity was higher than that required to exert antiplasmodial activity. Lethality in mice confirmed the higher toxicity and neurotoxicity of whole venom and fraction II, whereas Crotoxin B was not lethal at the doses tested. These results suggest the potential of Crotoxin B as a lead compound for antimalarial activity.

Analysis of phospholipase A2, L-amino acid oxidase, and proteinase enzymatic activities of the Lachesis muta rhombeata venom

The study of venom components is an important step toward understanding the mechanism of action of such venoms and is indispensable for the development of new therapies. This work aimed to investigate the venom of Lachesis muta rhombeata and evaluate enzymes related to its toxicity. Phospholipase A2 (PLA(2)), L-amino acid oxidase (LAAO), and proteinase activities were measured, and the molecular weights were estimated. We found the venom to contain one PLA(2) (17 kDa), one LAAO (132 kDa), and three serine proteinases (40, 31, and 20 kDa). Although only serine proteinases were observed in the zymogram, metalloproteinases were found to contribute more to the total proteolytic activity than did serine proteinases. The work confirmed the presence of highly active enzymes; and, moreover, we proposed a novel method for confirming the presence of LAAOs by zymography. We also suggested a simple step to increase the sensitivity of proteinase assays.

Past decade study of snake venom L-amino acid oxidase

As one of the major protein (enzyme) components of snake venom (SV), L-amino acid oxidase (LAAO) plays an important role in the toxicities and biological activities for SV. Accumulated researches in the past decade gradually revealed that SV-LAAOs induce platelet aggregation, cell apoptosis and cytotoxicity, and have anti-microbial, anti-leishmaniasis, anti-tumor and anti-HIV activity. Except for the enzymatic and structural characteristics of SV-LAAOs, the biological functions of SV-LAAOs and relevant action mechanisms are also summarized and discussed in the review. This work might provide useful inputs for future studies on SV-LAAOs.

Evaluation of an antimicrobial L-amino acid oxidase and peptide derivatives from Bothropoides mattogrosensis pitviper venom

Healthcare-associated infections (HAIs) are causes of mortality and morbidity worldwide. The prevalence of bacterial resistance to common antibiotics has increased in recent years, highlighting the need to develop novel alternatives for controlling these pathogens. Pitviper venoms are composed of a multifaceted mixture of peptides, proteins and inorganic components. L-amino oxidase (LAO) is a multifunctional enzyme that is able to develop different activities including antibacterial activity. In this study a novel LAO from Bothrops mattogrosensis (BmLAO) was isolated and biochemically characterized. Partial enzyme sequence showed full identity to Bothrops pauloensis LAO. Moreover, LAO here isolated showed remarkable antibacterial activity against Gram-positive and -negative bacteria, clearly suggesting a secondary protective function. Otherwise, no cytotoxic activities against macrophages and erythrocytes were observed. Finally, some LAO fragments (BmLAO-f1, BmLAO-f2 and BmLAO-f3) were synthesized and further evaluated, also showing enhanced antimicrobial activity. Peptide fragments, which are the key residues involved in antimicrobial activity, were also structurally studied by using theoretical models. The fragments reported here may be promising candidates in the rational design of new antibiotics that could be used to control resistant microorganisms.

Antibacterial and Antiparasitic Effects of Bothropoides lutzi venom

The therapeutic potential of toxins has aroused great interest in the scientific community. Microbial resistance is a serious current public health problem, in part because of the wide use of antimicrobial drugs. Furthermore, there are several problems in the treatment of parasitic diseases such as leishmaniosis and Chagas’ disease, including the low efficacy in some clinical phases of the diseases and the loss of effectiveness of benzonidazole in the chronic phase of Chagas’ disease. In this context, the aim of this work was to study the antimicrobial and antiparasitic effects of Bothropoides lutzi total venom (BltTV). The venom exerted an antibacterial effect on S. aureus, with MIC=MLC=200 μg/mL. The inhibitory effects of BltTV on promastigote forms of Leishmania amazonensis and L. chagasi were assessed by counting of viable cells after incubation with BltTV. IC50 values of 234.6 μg/mL and 61.2 μg/mL, were obtained, respectively. Furthermore, the venom repressed epimastigote forms of Trypanosoma cruzi growth. Finally, BltTV was verified to affect murine peritoneal macrophages, causing a cytotoxic effect at the highest concentrations (100 and 50 μg/mL). In conclusion, Bothropoides lutzi venom demonstrated antibacterial and antiparasite effects, suggesting that the venom contains some substance(s) of therapeutic value.

Bactericidal effect of Naja nigricollis toxin γ is related to its membrane-damaging activity

The aim of the present study is to investigate the causal relationship between membrane-damaging activity and bactericidal activity of Naja nigricollis toxin γ. Toxin γ showed a similar inhibitory activity on the growth of Staphylococcus aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria). Antibacterial activity of toxin γ correlated positively with increase in membrane permeability of bacterial cells. Morphological examination showed that toxin γ disrupted the integrity of bacterial membrane. Toxin γ showed similar binding capability with lipopolysaccharide (LPS) and lipoteichoic acid (LTA), and destabilization of LPS layer and inhibition of LTA biosynthesis on cell wall increased bactericidal effect of toxin γ on E. coli and S. aureus, respectively. Although the potency of toxin γ on permeabilizing model membrane of E. coli and S. aureus was similar, the mode of interaction between toxin γ and model membrane of E. coli and S. aureus differed. Membrane-damaging activity of toxin γ was inhibited by either LPS or LTA. Nevertheless, LPS and LTA altered differently membrane-bound conformation of toxin γ. Taken together, our data suggest that bactericidal activity of toxin γ depends on its ability to induce membrane permeability, and that LPS and LTA structurally suppresses bactericidal effect of toxin γ.

Membrane-damaging activity of Taiwan cobra cardiotoxin 3 is responsible for its bactericidal activity

This study investigates the causal relationship between membrane-damaging activity and bactericidal activity of Naja naja atra (Taiwan cobra) cardiotoxin 3 (CTX3). CTX3 showed greater inhibitory activity for the growth of Staphylococcus aureus (Gram-positive bacteria) relative to that of Escherichia coli (Gram-negative bacteria). The CTX3 antibacterial activity is positively correlated with the increase in membrane permeability of bacterial cells. Morphological examination showed that CTX3 disrupted bacterial membrane integrity.CTX3 showed similar binding capability with lipopolysaccharide (LPS) and lipoteichoic acid (LTA), and destabilization of LPS layer and inhibition of LTA biosynthesis on cell wall increased the CTX3 bactericidal effect on E. coli. and S. aureus, respectively. Compared with that of E. coli, CTX3 notably permeabilized model membrane of S. aureus. CTX3 membrane-damaging activity was inhibited by LPS and LTA, while increasing the CTX3 concentration counteracted the inhibitory action of LPS and LTA. Oxidation of Met residues on loop II of CTX3 simultaneously reduced the membrane-permeabilizing activity and bactericidal effect of CTX3. Taken together, our data indicate that CTX3 bactericidal activity depends highly on its ability to induce membrane permeability.

The serum of rabbitfish (Siganus oramin) has antimicrobial activity to some pathogenic organisms and a novel serum L-amino acid oxidase is isolated

The serum of rabbitfish (Siganus oramin) has been confirmed previously to have killing effect to Cryptocaryon irritans, an important marine ciliate protozoan that causes a disease referred to as "marine white spot disease". Herein, we find the serum of the rabbitfish also shows antibacterial activity against both gram-positive and gram-negative bacteria and has killing effect on two other parasites: Trypanosoma brucei brucei, Ichthyophthirius multifiliis. Results of scanning electron microscopy indicated that after treating with rabbitfish serum, the surface of the Staphylococcus aureus was wrinkled and pores were formed on the surface of Escherichia coli. Serum of the rabbitfish possesses a strong killing effect to Ichthyophthirius multifiliis in vitro, causing a similar effect as to C. irritans. The serum of rabbitfish also showed strong killing effect to T. b. brucei in vitro, with the minimus trypanocidal titre (MTT) only to be 1.5% in 1 h. Results of laser confocal fluorescence microscopy indicated that rabbitfish serum could also induce cell rupture of T. b. brucei. A novel antimicrobial protein (SR-LAAO) was isolated from the serum of rabbitfish by using ultrafiltration, reversed phase high performance liquid chromatography (RP-HPLC) and Native polyacrylamide gel electrophoresis (Native-PAGE). Results of gel overlay assay showed that the protein could act alone to inhibit the growth of S. aureus and E. coli. Results of western blot and automated Edman degradation showed that it was the same as the antiparasitic protein (APP) reported before to have killing effect on C. irritans. Full length cDNA sequence of the SR-LAAO was cloned. BLAST research suggested that the cDNA of SR-LAAO has a close similarity with a number of L-amino acid oxidases (LAAOs) and possesses two conserved motifs that exist in LAAOs. Combined, these results demonstrate that this protein which has antimicrobial activity to some pathogenic organisms was a novel LAAO found in the serum of rabbitfish. Immunohistochemical analysis demonstrated tissue specific expression and localization of SR-LAAO in the spleen, kidney, gill and blood of the rabbitfish, but was not found in other tissues. These results suggest that this protein may contribute considerably to the host non-specific immune defense mechanism to combat microbes of the rabbitfish and has the potency for using in future drug development.

A rational protocol for the successful crystallization of L-amino-acid oxidase from Bothrops atrox

Despite the valuable contributions of robotics and high-throughput approaches to protein crystallization, the role of an experienced crystallographer in the evaluation and rationalization of a crystallization process is still crucial to obtaining crystals suitable for X-ray diffraction measurements. In this work, the difficult task of crystallizing the flavoenzyme L-amino-acid oxidase purified from Bothrops atrox snake venom was overcome by the development of a protocol that first required the identification of a non-amorphous precipitate as a promising crystallization condition followed by the implementation of a methodology that combined crystallization in the presence of oil and seeding techniques. Crystals were obtained and a complete data set was collected to 2.3 Å resolution. The crystals belonged to space group P2(1), with unit-cell parameters a = 73.64, b = 123.92, c = 105.08 Å, β = 96.03°. There were four protein subunits in the asymmetric unit, which gave a Matthews coefficient V(M) of 2.12 Å(3) Da(-1), corresponding to 42% solvent content. The structure has been solved by molecular-replacement techniques.

Antibacterial action of a heat-stable form of L-amino acid oxidase isolated from king cobra (Ophiophagus hannah) venom

The major l-amino acid oxidase (LAAO, EC 1.4.3.2) of king cobra (Ophiophagus hannah) venom is known to be an unusual form of snake venom LAAO as it possesses unique structural features and unusual thermal stability. The antibacterial effects of king cobra venom LAAO were tested against several strains of clinical isolates including Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli using broth microdilution assay. For comparison, the antibacterial effects of several antibiotics (cefotaxime, kanamycin, tetracycline, vancomycin and penicillin) were also examined using the same conditions. King cobra venom LAAO was very effective in inhibiting the two Gram-positive bacteria (S. aureus and S. epidermidis) tested, with minimum inhibitory concentration (MIC) of 0.78μg/mL (0.006μM) and 1.56μg/mL (0.012μM) against S. aureus and S. epidermidis, respectively. The MICs are comparable to the MICs of the antibiotics tested, on a weight basis. However, the LAAO was only moderately effective against three Gram-negative bacteria tested (P. aeruginosa, K. pneumoniae and E. coli), with MIC ranges from 25 to 50μg/mL (0.2-0.4μM). Catalase at the concentration of 1mg/mL abolished the antibacterial effect of LAAO, indicating that the antibacterial effect of the enzyme involves generation of hydrogen peroxide. Binding studies indicated that king cobra venom LAAO binds strongly to the Gram-positive S. aureus and S. epidermidis, but less strongly to the Gram-negative E. coli and P. aeruginosa, indicating that specific binding to bacteria is important for the potent antibacterial activity of the enzyme.

Development of peptide and protein nanotherapeutics by nanoencapsulation and nanobioconjugation

The targeted delivery of therapeutic peptide by nanocarriers systems requires the knowledge of interactions of nanomaterials with the biological environment, peptide release, and stability of therapeutic peptides. Therapeutic application of nanoencapsulated peptides are increasing exponentially and >1000 peptides in nanoencapsulated form are in different clinical/trial phase. This review covers current scenario of therapeutic protein and peptides encapsulation on polymer to metallic nanocarriers including methods of protein encapsulation, peptide bioconjugation on nanoparticles, stability enhancement of encapsulated proteins and its biomedical applications.

Discovery of serum L-amino acid oxidase in the rockfish Sebastes schlegeli: isolation and biochemical characterization

Fish have a complex innate defense mechanism against microbial invasion. In particular, epidermal mucus and serum in fish play important roles in innate immunity and contain a variety of bioactive substances such as complements, lectins and lysozymes, involved in host defense. Recently, L-amino acid oxidases (LAOs) with antibacterial activity were isolated from the skin and/or gill mucous secretions of rockfish, great sculpin and flounder, and were identified to be a novel type of antibacterial protein in the integument of fish. In the present study, we found LAO activity in the serum of rockfish Sebastes schlegeli. The LAO was isolated from the serum by sequential column chromatography of Con-A lectin affinity chromatography, anion exchange HPLC, hydroxyapatite HPLC and gel filtration HPLC, and characterized. The LAO (a molecular mass of 160 kDa) comprised subunits with a molecular mass of 53 kDa and showed strict substrate specificity, catalyzing only L-lysine with Km 0.37 mM and kcat 57.1s(-1). The serum LAO exhibited a broad antibacterial activity against Gram positive and negative bacteria, most potently against Aeromonas hydrophila and Aeromonas salmonicida with a minimum inhibitory concentration of 0.078 μg/mL. This is the first report of LAO in the serum of fish and its involvement in innate immunity in the rockfish body.