Synthesis of analogs of peptides from Buthus martensii scorpion venom with potential antibiotic activity

Venom: A Promising Avenue for Antimicrobial Therapeutics

Venom in medicine is well documented in the chronicles of ancient Greece and the Roman Empire and persisted into the Renaissance and even into the modern era. Venoms were not always associated with detrimental consequences. Since ancient times, the curative capacity of venom has been recognized, portraying venom as a metaphor for pharmacy and medicine. Venom proteins and peptides' antimicrobial potential has not undergone systematic exploration despite the huge literature on natural antimicrobials. In light of the escalating challenge of antimicrobial resistance and the diminishing effectiveness of antibiotics, there is a pressing need for innovative antimicrobials capable of effectively addressing illnesses caused by multidrug-resistant microorganisms. This review adds to our understanding of the effectiveness of different venom components against a host of pathogenic microorganisms. The aim is to illuminate the various antimicrobials present in venom and venom peptides, thereby emphasizing the unexplored medicinal potential for antimicrobial properties. We have presented a concise summary of the molecular examination of the venom peptides' functioning processes, as well as the current clinical and preclinical progress of venom antimicrobial peptides.

A Critical Review of Short Antimicrobial Peptides from Scorpion Venoms, Their Physicochemical Attributes, and Potential for the Development of New Drugs

Scorpion venoms have proven to be excellent sources of antimicrobial agents. However, although many of them have been functionally characterized, they remain underutilized as pharmacological agents, despite their evident therapeutic potential. In this review, we discuss the physicochemical properties of short scorpion venom antimicrobial peptides (ssAMPs). Being generally short (13-25 aa) and amidated, their proven antimicrobial activity is generally explained by parameters such as their net charge, the hydrophobic moment, or the degree of helicity. However, for a complete understanding of their biological activities, also considering the properties of the target membranes is of great relevance. Here, with an extensive analysis of the physicochemical, structural, and thermodynamic parameters associated with these biomolecules, we propose a theoretical framework for the rational design of new antimicrobial drugs. Through a comparison of these physicochemical properties with the bioactivity of ssAMPs in pathogenic bacteria such as Staphylococcus aureus or Acinetobacter baumannii, it is evident that in addition to the net charge, the hydrophobic moment, electrostatic energy, or intrinsic flexibility are determining parameters to understand their performance. Although the correlation between these parameters is very complex, the consensus of our analysis suggests that there is a delicate balance between them and that modifying one affects the rest. Understanding the contribution of lipid composition to their bioactivities is also underestimated, which suggests that for each peptide, there is a physiological context to consider for the rational design of new drugs.

Biomedical applications of synthetic peptides derived from venom of animal origin: A systematic review

Development of therapeutic agents that have fewer adverse effects and have higher efficacy for diseases, such as cancer, metabolic disorders, neurological diseases, infections, cardiovascular diseases, and respiratory diseases, are required. Recent studies have focused on identifying novel sources for pharmaceutical molecules to develop therapies against these diseases. Among the sources for potentially new therapies, animal venom-derived molecules have generated much interest. Various animal venom-derived proteins and peptides have been isolated, identified, synthesized, and tested to develop drugs. Venom-derived peptides have several biomedical properties, such as proapoptotic, cell migration, and autophagy regulation activities in cancer cell models; induction of vasodilation by nitric oxide and regulation of angiotensin II; modification of insulin response by controlling calcium and potassium channels; regulation of pain receptor activity; modulation of immune cell activity; alteration of motor neuron activity; degradation or inhibition of β-amyloid plaque formation; antibacterial, antifungal, antiviral, and antiprotozoal activities; increase in sperm motility and potentiation of erectile function; reduction of intraocular pressure; anticoagulation, fibrinolytic, and antithrombotic activities; etc. This systematic review compiles these biomedical properties and potential biomedical applications of synthesized animal venom-derived peptides reported in the latest research. In addition, the limitations and areas of opportunity in this research field are discussed so that new studies can be developed based on the data presented.

Antibacterial polypeptide-bioparticle for oral administration: Powder formulation, palatability and in vivo toxicity approach

The upsurge of bacterial resistance to conventional antibiotics turned a well-recognized public health threat. The need of developing new biomaterials of effective practical use in order to tackle bacterial resistance became urgent. In this study, a submicrometric bioparticle of known antibacterial activity was produced in powder form with suitable texture and appealing characteristics for effective oral administration. Through complex coacervating a natural-source antimicrobial polypeptide with chitosan-N-arginine and alginate, the bioactive polypeptide was physically incorporated to the bioparticle whose structure positively responds to the pH variations found in gastrointestinal tract. The powder formulation presented high palatability that was evaluated using fish as in vivo animal model. A thorough survey of the fish intestinal tissues, following a systematic oral administration, revealed high penetration potential of the biomaterial through epithelial cells and deeper intestine layers. Despite, no cytotoxic effect was observed in analyzing the tissues through different histology methods. The absence of intestinal damage was corroborated by immune histochemistry, being the integrity of epithelial motor myosin Vb and related traffic proteins preserved. Hematology further endorsed absence of toxicity in blood cells whose morphology was evaluated in detail. The study evidenced the applicability potential of a new biomaterial of appealing and safe oral administration of antibacterial polypeptide.

Effect from dinoponeratoxin M-PONTXDq3a arginine and lysine substituted analogues against Staphylococcus aureus strains

The growing incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections is associated with increased mortality rates, which has generated interest in the development of antimicrobial peptides (AMP), such as those found in the giant ant Dinoponera quadríceps. In order to improve the net positive charge and the antibacterial activity of the AMP, amino acids with positive side chain single substituted analogues have been proposed, mainly arginine or lysine. The present work aims to study the antimicrobial activity of the analogues of M-PONTX-Dq3a, a 23 amino acid AMP identified in the D. quadriceps venom. M-PONTX-Dq3a[1-15], a fragment containing the 15 central amino acids, and eight derivatives of single arginine or lysine substituted analogues were proposed. The antimicrobial activity of peptides was evaluated against Staphylococcus aureus ATCC 6538 P (MSSA) and ATCC 33591 (MRSA) strains, followed by minimum inhibitory concentration (MIC), minimum lethal concentration (MLC), and minimum biofilm inhibitory concentration (MBIC) measurement. The membrane permeability was then assessed via crystal violet assay and flow cytometry analysis. The effect of exposure time on microbial viability (Time-Kill) was evaluated. Finally, ultrastructural alterations were evaluated through scanning electron microscopy (SEM). Both arginine-substituted peptides [Arg]3M-PONTX-Dq3a[1-15] and [Arg]4M-PONTX-Dq3a[1-15], showed lowest MIC and MLC values (each 0.78 μM). In the biofilm formation assays, the peptide [Arg]3M-PONTX-Dq3a [1-15] showed MBIC of 3.12 μM against the two tested strains. Both peptides were able to alter the membrane permeability approximately by 80%. The treatment with MIC was able to eliminate bacteria after 2 h of contact on the other hand, treatment with half of the MIC, the population of both bacterial strains remained constant for up to 12 h, indicating a possible bacteriostatic effect. The SEM results showed that the treatment with the lowest concentration (0.78 μM) of both peptides caused disruption of the cell membrane, destabilization of the intercellular interaction and the CLM of [Arg]4M-PONTX-Dq3a [1-15] resulted in the complete eradication of the bacteria. Thus, this study describes two AMPs active against MSSA and MRSA and also inhibits the biofilm formation of these stains. This study finds [Arg]3M-PONTX-Dq3a[1-15] and [Arg]4M-PONTX-Dq3a[1-15] as alternative substances to treat resistant and/or biofilm-forming strains.

Synthesized peptide analogs from Eumenes pomiformis (Hymenoptera: Eumenidae) venom reveals their antibiotic and pesticide activity potential

One natural antimicrobial peptide (EpVP2a, Eumenes pomiformis Venom Peptide 2a) found in the venom of a potter wasp (Eumenes pomiformis) and six analogs were synthesized and tested to compare their antimicrobial, antifungal, pesticide, and hemolytic activity with the wild type. Our results indicated that while the original peptide and the synthetic analogs had no antifungal activity or anti-bacterial activity against Pseudomonas aeruginosa, the original peptide and the analog with substitution of the aspartic acid on the sequence by a lysine (EpVP2a-D2K2) had activity against Escherichia coli, Staphylococcus aureus and Bacillus subtilis. This same analog also shows significant insecticide activity. The analog with substitution of lysine with a slightly smaller ornithine had activity against E. coli and B. subtilis. All analogs show low hemolytic activity compared to the natural peptide. The peptide with a reverse sequence to the natural one (EpVp2a Retro) shows low helix structure which can also explain why it has no antibacterial activity and low hemolytic activity. Circular dichroism spectra show that these peptides form an alpha helix structure and their amino acid positions predict an amphipathic nature.

Antimicrobial Peptide Analogs From Scorpions: Modifications and Structure-Activity

The rapid development of multidrug-resistant pathogens against conventional antibiotics is a global public health problem. The irrational use of antibiotics has promoted therapeutic limitations against different infections, making research of new molecules that can be applied to treat infections necessary. Antimicrobial peptides (AMPs) are a class of promising antibiotic molecules as they present broad action spectrum, potent activity, and do not easily induce resistance. Several AMPs from scorpion venoms have been described as a potential source for the development of new drugs; however, some limitations to their application are also observed. Here, we describe strategies used in several approaches to optimize scorpion AMPs, addressing their primary sequence, biotechnological potential, and characteristics that should be considered when developing an AMP derived from scorpion venoms. In addition, this review may contribute towards improving the understanding of rationally designing new molecules, targeting functional AMPs that may have a therapeutic application.

Antimicrobial Activity and Toxicity of Analogs of Wasp Venom EMP Peptides. Potential Influence of Oxidized Methionine

The antibiotic and toxic properties for four synthetic analogs of eumenine mastoparan peptides (EMP) have been tested. These properties were compared to two natural peptides found in the venom of solitary wasps Anterhynchium flavomarginatum micado (natural peptide EMP-AF) and Eumenes rubrofemoratus (natural peptide EMP-ER), respectively. Only EMP-AF-OR showed concentration-dependent growth inhibition against all bacterial species tested. Gram positive species had MIC values of 10 μg/mL for B. subtilis and 25 μg/mL for S. aureus. Gram negative species had MIC values of 25 μg/mL for E. coli and 200 μg/mL for P. aeruginosa. Of the other tested peptides, EMP-ER-D2K2 also showed activity and inhibited growth of Bacillus subtilis in a concentration-dependent manner at 200 μg/mL. Peptide EMP-ER-OR reduced the final density of Escherichia coli and B. subtilis cultures but did not impact their growth kinetics. Peptides EMP-AF-OR, EMP-ER-OR, and EMP-ER-D2K2 showed limited antifungal activity against Candida albicans or Histoplasma capsulatum. The hemolytic activity of the analogs were moderated though reports of the natural peptides, especially EMP-AF-OR, already showed low toxicity against erythrocytes. These results are discussed in the context of the potential influence of oxidized methionine on EMP activity.

Purificación parcial de péptidos del veneno de escorpión Hadruroides charcasus (Karsch, 1879) con actividad antimicrobiana

Los venenos de muchas especies de escorpiones son fuentes ricas en componentes biológicamente activos, como los péptidos antimicrobianos, biomoléculas que aún no han sido estudiados del veneno de Hadruroides charcasus. El objetivo de este artículo es evaluar la actividad antimicrobiana de los péptidos parcialmente purificados del veneno del escorpión Hadruroides. asus. A partir de 15,46 mg de proteína total del veneno del escorpión H. charcasus se purificaron parcialmente sus péptidos por medio de cromatografía de filtración en gel empleando sephadex G-75, consecutivo a una cromatografía de intercambio iónico en CM-Sephadex C-25. El peso molecular estimado de los péptidos se determinó mediante electroforesis PAGE-SDS-Tris-Tricina al 15% y la evaluación de la actividad antibacteriana y antifúngica se empleó el método de microdilución y Kirby-Bauer con cepas de Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853 y Candida albicans ATCC 10231. En la cromatografía de filtración en gel se obtuvieron 5 fracciones, de lo cual, la fracción IV presentó una concentración mínima inhibitoria de 3,6 mg/mL en S. aureus ATCC 29213 y en C. albicans ATCC 10231. De la cromatografía de intercambio se obtuvieron 7 fracciones, destacando la fracción OPDIV-5 con péptidos de 4 kDa; 5 kDa; 5,5 kDa y 6,4 kDa que presentó actividad antimicrobiana frente S. aureus ATCC 29213, E. coli ATCC 25922, P. aeruginosa ATCC 27853, C. albicans ATCC 10231.El veneno del escorpión H. charcasus presenta péptidos de naturaleza catiónica con actividad antibacteriana y antifúngica, según su actividad en las cepas evaluadas.

NMR three-dimensional structure of the cationic peptide Stigmurin from Tityus stigmurus scorpion venom: In vitro antioxidant and in vivo antibacterial and healing activity

Infectious diseases and the rapid development of pathogens resistant to conventional drugs are a serious global public health problem, which motivates the search for new pharmacological agents. In this context, cationic peptides without disulfide bridges from different species of scorpion venom have been the target of scientific studies due to their multifunctional activities. Stigmurin is a linear peptide composed of 17 amino acid residues (Phe-Phe-Ser-Leu-Ile-Pro-Ser-Leu-Val-Gly-Gly-Leu-Ile-Ser-Ala-Phe-Lys-NH₂), which is present in the venom gland of the scorpion Tityus stigmurus. Here we present investigations of the in vitro antioxidant action of Stigmurin together with the in vivo antibacterial and healing activity of this peptide in a wound infection model induced by Staphylococcus aureus. In addition, we have reports for the first time of the three-dimensional structure determined by NMR spectroscopy of a peptide without disulfide bridges present in scorpion venom from the Tityus genus. Stigmurin showed hydroxyl radical scavenging above 70 % at 10 μM and antibiotic action in the skin wound, reducing the number of viable microorganisms by 67.2 % on the 7 day after infection. Stigmurin (1 μg / μL) increased the retraction rate of the lesion, with wound area reduction of 43 % on the second day after skin injury, which indicates its ability to induce tissue repair. Stigmurin in trifluoroethanol:water exhibited a random conformation at the N-terminus region (Phe1 to Pro6), with a helical structure from Ser7 to Phe16. This structural information, allied with the multifunctional activity of Stigmurin, makes it an attractive candidate for the design of novel therapeutic agents.

Potent and Broad-Spectrum Antimicrobial Activity of Analogs from the Scorpion Peptide Stigmurin

Scorpion venom constitutes a rich source of biologically active compounds with high potential for therapeutic and biotechnological applications that can be used as prototypes for the design of new drugs. The aim of this study was to characterize the structural conformation, evaluate the antimicrobial activity, and gain insight into the possible action mechanism underlying it, for two new analog peptides of the scorpion peptide Stigmurin, named StigA25 and StigA31. The amino acid substitutions in the native sequence for lysine residues resulted in peptides with higher positive net charge and hydrophobicity, with an increase in the theoretical helical content. StigA25 and StigA31 showed the capacity to modify their structural conformation according to the environment, and were stable to pH and temperature variation—results similar to the native peptide. Both analog peptides demonstrated broad-spectrum antimicrobial activity in vitro, showing an effect superior to that of the native peptide, being non-hemolytic at the biologically active concentrations. Therefore, this study demonstrates the therapeutic potential of the analog peptides from Stigmurin and the promising approach of rational drug design based on scorpion venom peptide to obtain new anti-infective agents.

Analogs of the Scorpion Venom Peptide Stigmurin: Structural Assessment, Toxicity, and Increased Antimicrobial Activity

Scorpion venom is a rich source of biologically active components and various peptides with high-potential therapeutic use that have been characterized for their antimicrobial and antiproliferative activities. Stigmurin is a peptide identified from the Tityus stigmurus venom gland with high antibacterial and antiproliferative activities and low toxicity. Amino acid substitutions in peptides without a disulfide bridge sequence have been made with the aim of reducing their toxicity and increasing their biological activities. The purpose of this study was to evaluate the structural conformation and structural stability, as well as antimicrobial, antiproliferative, and hemolytic activities of two peptide analogs to Stigmurin, denominated StigA6 and StigA16. In silico analysis revealed the α-helix structure for both analog peptides, which was confirmed by circular dichroism. Data showed that the net charge and hydrophobic moment of the analog peptides were higher than those for Stigmurin, which can explain the increase in antimicrobial activity presented by them. Both analog peptides exhibited activity on cancerous cells similar to the native peptide; however, they were less toxic when tested on the normal cell line. These results reveal a potential biotechnological application of the analog peptides StigA6 and StigA16 as prototypes to new therapeutic agents.

Mesobuthus Venom-Derived Antimicrobial Peptides Possess Intrinsic Multifunctionality and Differential Potential as Drugs

Animal venoms are a mixture of peptides and proteins that serve two basic biological functions: predation and defense against both predators and microbes. Antimicrobial peptides (AMPs) are a common component extensively present in various scorpion venoms (herein abbreviated as svAMPs). However, their roles in predation and defense against predators and potential as drugs are poorly understood. Here, we report five new venom peptides with antimicrobial activity from two Mesobuthus scorpion species. These α-helical linear peptides displayed highly bactericidal activity toward all the Gram-positive bacteria used here but differential activity against Gram-negative bacteria and fungi. In addition to the antibiotic activity, these AMPs displayed lethality to houseflies and hemotoxin-like toxicity on mice by causing hemolysis, tissue damage and inducing inflammatory pain. Unlike AMPs from other origins, these venom-derived AMPs seem to be unsuitable as anti-infective drugs due to their high hemolysis and low serum stability. However, MeuTXKβ1, a known two-domain Mesobuthus AMP, is an exception since it exhibits high activity toward antibiotic resistant Staphylococci clinical isolates with low hemolysis and high serum stability. The findings that the classical AMPs play predatory and defensive roles indicate that the multifunctionality of scorpion venom components is an intrinsic feature likely evolved by natural selection from microbes, prey and predators of scorpions. This definitely provides an excellent system in which one can study how a protein adaptively evolves novel functions in a new environment. Meantimes, new strategies are needed to remove the toxicity of svAMPs on eukaryotic cells when they are used as leads for anti-infective drugs.

Antibacterial Activity and Toxicity of Analogs of Scorpion Venom IsCT Peptides

Seven analogs of the natural, α-helix peptides IsCT1 and IsCT2-found in the venom of scorpion Opithancatus Madagascariensis-have been synthesized and tested to compare their antibacterial and hemolytic activity against natural peptides. In general, results show that increasing hydrophobicity by substituting positions 5 and 9 of the sequences with alanine, valine, and leucine, enhances antibacterial activity. However, this also increases hemolytic activity. The analog with an increased net positive charge from +1 to +3 produces moderate bacterial growth inhibition but also has high hemolytic activity. On the other hand, the analog with a negative net charge (-1) has low antibacterial properties but also no cytotoxicity under the tested conditions, a similar result was found for five of the seven studied analogs.

A Novel Defensin-Like Peptide Associated with Two Other New Cationic Antimicrobial Peptides in Transcriptome of the Iranian Scorpion Venom

INTRODUCTION

Scorpion venom is a source of bioactive peptides, and some antimicrobial peptides (AMPs) have been found in the venom gland of scorpions. Therefore, the discovery of new anti-infective agents is an essential need to overcome the problem of antibiotic resistance of clinical isolates. Here, we describe three new cationic AMPs, including meuVAP-6, meuAP-18-1, and meuPep34 from the venom gland of the Iranian scorpion, Mesobuthus eupeus.

METHODS

The cDNA sequences encoding all the three peptides were obtained from the cDNA library of scorpion venom gland and were deposited in the GenBank database.

RESULTS

MeuVAP-6 and meuAP-18-1 are non-disulphide-bridged antimicrobial peptides, while meuPep34 is a cysteine-rich defensin-like peptide.

DISCUSSION

All three identified AMPs are rich in arginine and tryptophan. The overall results from the length, net charge, and hydrophobicity index suggested that meuPep34 could be the most active AMPs with the potential ability of biofilm inhibition. The data from molecular characterization of identified AMPs can provide a platform for further investigations in the drug design.

rBmαTX14 Increases the Life Span and Promotes the Locomotion of Caenorhabditis Elegans

The scorpion has been extensively used in various pharmacological profiles or as food supplies. The exploration of scorpion venom has been reported due to the presence of recombinant peptides. rBmαTX14 is an α-neurotoxin extracted from the venom gland of the East Asian scorpion Buthus martensii Karsch and can affect ion channel conductance. Here, we investigated the functions of rBmαTX14 using the Caenorhabditis elegans model. Using western blot analysis, rBmαTX14 was shown to be expressed both in the cytoplasm and inclusion bodies in the E.coli Rosetta (DE3) strain. Circular dichroism spectroscopy analysis demonstrated that purified rBmαTX14 retained its biological structures. Next, feeding nematodes with E.coli Rosetta (DE3) expressing rBmαTX14 caused extension of the life span and promoted the locomotion of the nematodes. In addition, we identified several genes that play various roles in the life span and locomotion of C. elegans through microarray analysis and quantitative real-time PCR. Furthermore, if the amino acid site H₁₅ of rBmαTX14 was mutated, rBmαTX14 no longer promoted the C. elegans life span. In conclusion, the results not only demonstrated the functions and mechanism of rBmαTX14 in C. elegans, but also provided the new sight in the utility of recombinant peptides from scorpion venom.

The Schistosome Esophagus Is a 'Hotspot' for Microexon and Lysosomal Hydrolase Gene Expression: Implications for Blood Processing

Background

The schistosome esophagus is divided into anterior and posterior compartments, each surrounded by a dense cluster of gland cell bodies, the source of distinct secretory vesicles discharged into the lumen to initiate the processing of ingested blood. Erythrocytes are lysed in the lumen, leucocytes are tethered and killed and platelets are eliminated. We know little about the proteins secreted from the two glands that mediate these biological processes.

Methodology/Principal Findings

We have used subtractive RNA-Seq to characterise the complement of genes that are differentially expressed in a head preparation, compared to matched tissues from worm tails. The expression site of representative highlighted genes was then validated using whole munt in situ hybridisation (WISH). Mapping of transcript reads to the S. mansoni genome assembly using Cufflinks identified ~90 genes that were differentially expressed >fourfold in the head preparation; ~50 novel transcripts were also identified by de novo assembly using Trinity. The largest subset (27) of secreted proteins was encoded by microexon genes (MEGs), the most intense focus identified to date. Expression of three (MEGs 12, 16, 17) was confirmed in the anterior gland and five (MEGs 8.1, 9, 11, 15 and 22) in the posterior gland. The other major subset comprised nine lysosomal hydrolases (aspartyl proteases, phospholipases and palmitoyl thioesterase), again localised to the glands.

Conclusions

A proportion of the MEG-encoded secretory proteins can be classified by their primary structure. We have suggested testable hypotheses about how they might function, in conjunction with the lysosomal hydrolases, to mediate the biological processes that occur in the esophagus lumen. Antibodies bind to the esophageal secretions in both permissive and self-curing hosts, suggesting that the proteins represent a novel panel of untested vaccine candidates. A second major task is to identify which of them can serve as immune targets.

Schistosomes feed on blood and we have previously shown that its processing begins in the esophagus, which does not act simply as a conduit. It comprises anterior and posterior compartments, each surrounded by glands that secrete proteins into the lumen. Erythrocytes are ruptured as they pass through the compartments and leucocytes are tethered and killed but blood fails to clot. We wanted to identify the proteins secreted from these glands by sequencing the transcriptomes of head and tail preparations to pinpoint those messenger RNAs predominantly or exclusively present only in the heads. We found approximately 50 such proteins, the largest group of 27 being encoded by microexon genes. A second group comprised hydrolytic enzymes that operate at an acid pH. We showed by hybridisation experiments that expression of these genes is indeed localised to either the anterior or the posterior gland. We have suggested that this complex mixture of secreted proteins act together to perform the biological processes that occur in the lumen or, in the case of O-glycosylated membrane proteins, form a protective lining coat. We now want to discover which of them can serve as immune targets in infected animal hosts.