Antimicrobial and Anticancer Properties of Synthetic Peptides Derived from the Wasp Parachartergus fraternus

Employment of mastoparan-like peptides to prevent Staphylococcus aureus associated with bovine mastitis

Bovine mastitis is a frequent infection in lactating cattle, causing great economic losses. Staphylococcus aureus represents the main etiological agent, which causes recurrent and persistent intramammary infections because conventional antibiotics are ineffective against it. Mastoparan-like peptides are multifunctional molecules with broad antimicrobial potential, constituting an attractive alternative. Nevertheless, their toxicity to host cells has hindered their therapeutic application. Previously, our group engineered three mastoparan-L analogs, namely mastoparan-MO, mastoparan-R1, and [I5, R8] MP, to improve cell selectivity and potential. Here, we were interested in comparing the antibacterial efficacy of mastoparan-L and its analogs against bovine mastitis isolates of S. aureus strains, making a correlation with the physicochemical properties and structural arrangement changes promoted by the sequence modifications. As a result, the analog's hemolytic and/or antimicrobial activity was balanced. All the peptides displayed α-helical folding in hydrophobic and membrane-mimetic environments, as determined by circular dichroism. The peptide [I5, R8] MP stood out for its enhanced selectivity and antibacterial features related to mastoparan-L and the other derivatives. Biophysical approaches revealed that [I5, R8] MP rapidly depolarizes the bacterial membrane of S. aureus, causing cell death by subsequent membrane disruption. Our results demonstrated that the [I5, R8] MP peptide could be a starting point for the development of peptide-based drugs for the treatment of bovine mastitis, with the advantage of no residue in milk, which would help reduce the use of classical antibiotics.IMPORTANCEStaphylococcus aureus is a leading cause of mastitis, the world's most important dairy cattle disease. The multidrug resistance and zoonotic potential of S. aureus, besides the likelihood of antibiotic residues in milk, are of critical concern to public and animal health. Antimicrobial peptides offer a novel antimicrobial strategy. Here, we demonstrate that [I5, R8] MP is a potent and selective peptide, which acts on S. aureus by targeting the bacterial membrane. Therefore, understanding the physicochemical determinants and the modes of action of this class of antimicrobials opens novel prospects for peptide development with enhanced activities in the bovine mastitis context.

Unwrapping the structural and functional features of antimicrobial peptides from wasp venoms

The study of wasp venoms has captured attention due to the presence of a wide variety of active compounds, revealing a diverse array of biological effects. Among these compounds, certain antimicrobial peptides (AMPs) such as mastoparans and chemotactic peptides have emerged as significant players, characterized by their unique amphipathic short linear alpha-helical structure. These peptides exhibit not only antibiotic properties but also a range of other biological activities, which are related to their ability to interact with biological membranes to varying degrees. This review article aims to provide updated insights into the structure/function relationships of AMPs derived from wasp venoms, linking this knowledge to the potential development of innovative treatments against infections.

Cell Penetrating Peptides: Classification, Mechanisms, Methods of Study, and Applications

Cell-penetrating peptides (CPPs) encompass a class of peptides that possess the remarkable ability to cross cell membranes and deliver various types of cargoes, including drugs, nucleic acids, and proteins, into cells. For this reason, CPPs are largely investigated in drug delivery applications in the context of many diseases, such as cancer, diabetes, and genetic disorders. While sharing this functionality and some common structural features, such as a high content of positively charged amino acids, CPPs represent an extremely diverse group of elements, which can differentiate under many aspects. In this review, we summarize the most common characteristics of CPPs, introduce their main distinctive features, mechanistic aspects that drive their function, and outline the most widely used techniques for their structural and functional studies. We highlight current gaps and future perspectives in this field, which have the potential to significantly impact the future field of drug delivery and therapeutics.

Exploring the therapeutic potential of an antinociceptive and anti-inflammatory peptide from wasp venom

Animal venoms are rich sources of neuroactive compounds, including anti-inflammatory, antiepileptic, and antinociceptive molecules. Our study identified a protonectin peptide from the wasp Parachartergus fraternus' venom using mass spectrometry and cDNA library construction. Using this peptide as a template, we designed a new peptide, protonectin-F, which exhibited higher antinociceptive activity and less motor impairment compared to protonectin. In drug interaction experiments with naloxone and AM251, Protonectin-F's activity was decreased by opioid and cannabinoid antagonism, two critical antinociception pathways. Further experiments revealed that this effect is most likely not induced by direct action on receptors but by activation of the descending pain control pathway. We noted that protonectin-F induced less tolerance in mice after repeated administration than morphine. Protonectin-F was also able to decrease TNF-α production in vitro and modulate the inflammatory response, which can further contribute to its antinociceptive activity. These findings suggest that protonectin-F may be a potential molecule for developing drugs to treat pain disorders with fewer adverse effects. Our results reinforce the biotechnological importance of animal venom for developing new molecules of clinical interest.

Inspiration from cruzioseptin-1: membranolytic analogue with improved antibacterial properties

Peptide engineering has gained attraction as a source of new cationicity-enhanced analogues with high potential for the design of next-generation antibiotics. In this context, cruzioseptin-1 (CZS-1), a peptide identified from Cruziohyla calcarifer, is recognized for its antimicrobial potency. However, this amidated-peptide is moderately hemolytic. In order to reduce toxicity and increase antimicrobial potency, 3 peptide analogues based on cruzioseptin-1 were designed and evaluated. [K4K15]CZS-1, an analogue with increased cationicity and reduced hydrophobicity, showed antibacterial, antifungal and antiproliferative properties. In addition, [K4K15]CZS-1 is less hemolytic than CZS-1. The in silico and scanning electron microscopy analysis reveal that [K4K15]CZS-1 induces a membranolytic effect on bacteria. Overall, these results confirm the potential of CZS-1 as source of inspiration for design new selective antimicrobial analogues useful for development of new therapeutic agents.

Antimicrobial Peptides with Antibacterial Activity against Vancomycin-Resistant Staphylococcus aureus Strains: Classification, Structures, and Mechanisms of Action

The emergence of bacteria resistant to conventional antibiotics is of great concern in modern medicine because it renders ineffectiveness of the current empirical antibiotic therapies. Infections caused by vancomycin-resistant Staphylococcus aureus (VRSA) and vancomycin-intermediate S. aureus (VISA) strains represent a serious threat to global health due to their considerable morbidity and mortality rates. Therefore, there is an urgent need of research and development of new antimicrobial alternatives against these bacteria. In this context, the use of antimicrobial peptides (AMPs) is considered a promising alternative therapeutic strategy to control resistant strains. Therefore, a wide number of natural, artificial, and synthetic AMPs have been evaluated against VRSA and VISA strains, with great potential for clinical application. In this regard, we aimed to present a comprehensive and systematic review of research findings on AMPs that have shown antibacterial activity against vancomycin-resistant and vancomycin-intermediate resistant strains and clinical isolates of S. aureus, discussing their classification and origin, physicochemical and structural characteristics, and possible action mechanisms. This is the first review that includes all peptides that have shown antibacterial activity against VRSA and VISA strains exclusively.

Protonectin peptides target lipids, act at the interface and selectively kill metastatic breast cancer cells while preserving morphological integrity

Despite the need for innovative compounds as antimicrobial and anticancer agents, natural sources of peptides remain underexplored. Protonectin (PTN), a cationic dodecapeptide of pharmacological interest, presents large hydrophobicity that is associated with the tendency to aggregate and supposedly influences bioactivity. A disaggregating role was assigned to PTN' N-terminal fragment (PTN_1-6), which enhances the bioactivity of PTN in a 1:1 mixture (PTN/PTN_1-6). Spectroscopic techniques and model membranes (phospholipid bilayers and SDS micelles) revealed that environment-dependent aggregation is reduced for PTN/PTN_1-6, but cytotoxicity of PTNs on MDA-MB-231 breast cancer showed the same CC₅₀ values around 16 µM and on MCF-10A epithelial breast cells 6 to 5-fold higher values, revealing a selective interaction. Since PTN_1-6 lacks activity on breast cells, its presence should differently affect PTN activity, suggesting that aggregation could modulate activity depending on the membrane characteristics. Indeed, increased partitioning and lytic activity of PTN/PTN_1-6 were found in model membranes independently of charge density, but affected by the curvature tendency. PTN and PTN/PTN_1-6 do not alter morphology and roughness of cancer cells, indicating a superficial interaction with membranes and consistent with results obtained in NMR experiments. Our results indicate that aggregation of PTNs depends on the membrane characteristics and modulates the activity of the peptides.