B1CTcu5 analogs as promising antimicrobial peptides, replacing the sequence cysteine (original) (raw)
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Experimental evaluation of antimicrobial effects of the synthetic peptide on pathogenic bacteria
2014
Antibiotics are common anti-infection drugs used these days. However, their excessive applications have led to the rising antibiotic resistance, a serious phenomenon in modern medicine that is regarded as one of the pre-eminent public health concerns of the 21st century. As a result, there is a growing need to find alternative drugs to eradicate the microbial resistance. Antimicrobial peptides (AMPs) are natural defence molecules found in virtually all life forms. They are evolutionary conserved components of the innate immune defence. AMPs utilize different mechanisms of action for killing bacteria, which can vary depending on a type of particular bacterium. Generally, AMPs are broad-spectrum antibiotics that act not only against bacteria but also certain viruses and fungi. A number of studies suggested a possibility of using AMPs as an alternative therapy for treatment of microbial infections.
Antimicrobial Peptides from Bacterial Sources-A Review
2020
Antimicrobial peptides are host defense peptides composed of long chain of amino acids with a lot many properties. The antimicrobial peptides produced by bacteria are collectively called as bacteriocins. Bacteriocins are produced by both Gram positive and Gram negative bacteria and are positively charged or amphiphilic molecules. Even though both Gram negative and Gram positive bacteria produce bacteriocins, those produced by Gram positive Lactic Acid Bacteria are most studied and diverse in nature. They are classified into lantibiotics and Cl;ass II peptides. These peptides are having antibacterial, immunomodulatory activities and even antibacterial resistance. They act by forming pores in the cell membrane and thus causing the cell death. Bacteria secrete these peptides as a defense strategy to defend their environment and also able to kill other bacteria. Even though having many beneficial properties and uses, there many challenges in clinical use of these peptides.
"In recent years, the widespread use of antibiotics has caused many bacterial pathogens resistance to conventional antibiotics. Therefore, generation of new antibiotics to control and reduce the effects of these pathogens is urgently needed. Antimicrobial peptides and proteins are important members of the host defense system in eukaryotes. These peptides are potent, broad-spectrum antibiotics that demonstrate potential as novel and alternative therapeutic agents for the treatment of drug-resistant infections. Accordingly, we evaluated two hybrid peptides CM11 (WKLFKKILKVL-NH2) and CM15 (KWKLFKKIGAVLKVL-NH2) on five important pathogenic bacteria. These peptides are short cecropin–melittin hybrid peptides obtained through a sequence combination approach, which are highly effective to inhibit the growth of important pathogenic bacteria. The activity of these two cationic peptides (CM11 and CM15) in different concentrations (2–64 mg/L) was investigated against standard and clinical isolates of important hospital infection bacteria by measuring MIC, MBC, and bactericidal assay. These peptides demonstrated the same ranges of inhibitory values: The organisms in early 24 h were more susceptible to polycationic peptides (MIC: 8 mg/L and MBC 32 mg/L), but after 48 h the MIC and MBC remained constant for the CM11 peptide. Bactericidal assay showed that all bacteria strains did not have any growth in agar plates after 40 min. The result showed that these two peptides are more effective than other peptides"
Design of Synthetic Antimicrobial Peptides Based on Sequence Analogy and Amphipathicity
European Journal of Biochemistry, 1997
Novel A-helical antimicrobial peptides have been devised by comparing the N-terminal sequences of many of these peptides from insect, frog and mammalian families, extracting common features, and creating sequence templates with which to design active peptides. Determination of the most frequent amino acids in the first 20 positions for over 80 different natural sequences allowed the design of one peptide, while a further three were based on the comparison of the sequences of A-helical antimicrobial peptides derived from the mammalian cathelicidin family of precursors. These peptides were predicted to assume a highly amphipathic A-helical conformation, as indicated by high mean hydrophobic moments. In fact, circular dichroism experiments showed clear transitions from random coil in aqueous solution to an A-helical conformation on addition of trifluoroethanol. All four peptides displayed a potent antibacterial activity against selected gram-positive and gram-negative bacteria (minimum inhibitory concentrations in the range 1Ϫ8 µM), including some antibiotic resistant strains. Permeabilization of both the outer and cytoplasmic membranes of the gram-negative bacterium, Escherichia coli, by selected peptides was quite rapid and a dramatic drop in colony forming units was observed within 5 min in time-killing experiments. Permeabilization of the cytoplasmic membrane of the gram-positive bacterium, Staphylococcus aureus, was instead initially quite slow, gathering speed after 45 min, which corresponds to the time required for significant inactivation in time-killing studies. The cytotoxic activity of the peptides, determined on several normal and transformed cell lines, was generally low at values within the minimum inhibitory concentration range.
Update of peptides with antibacterial activity
For many years a battle has been going on between bacteria and humans, with bacteria trying to survive against the antibiotics used by humans. Bacteria are found to be dominant in this battle since they can develop resistance. In fact, in the last decade multi-, extended-and pan-drug resistant bacteria have been isolated. On the other hand, the number of new antibiotics approved by the FDA has dramatically decreased during the last 20 years. Therefore, there is a desperate need for developing new types of antibacterial agents, where antimicrobial peptides may play an important role. This review provides an update of the recently identified antimicrobial peptides. Three valid approaches for developing a future antibacterial agent, as are the mechanisms of action as well as the in vitro and in vivo assays have been described in depth. In comparison to the antibacterial agents available at present, the targets for most of the antimicrobial peptides are not well known. However several proposals having been introduced for many antimicrobial peptides of different mechanisms of action, there still lies some uncertainty about their utility. Hundreds of antimicrobial peptides have been tested in vitro against all types of bacteria, but in this review we will highlight only those which have been tested against the most important Grampositive and Gram-negative bacteria. The last step to get a potential antibiotic includes studies with an in vivo model. Therefore only antimicrobial peptides with good activity are tested that have been described in this review.
Utilisation of peptides against microbial infections – a review
Annals of Agricultural and Environmental Medicine
The emergence of resistance in microorganisms on a global scale has made it necessary to search for new antimicrobial factors. Antimicrobial peptides (AMPs) seem to meet these expectations. AMPs are produced by bacteria, viruses, plants, and animals, and may be considered as a new class of drugs intended for the prophylaxis and treatment of both systemic and topical infections. The aim of this study is to review the results of studies on the use of peptides to combat infections in vivo. Antimicrobial peptides may be applied topically and systemically. Among the peptides used topically, a very important area for their application is ophthalmology. AMPs in ophthalmology may be used mainly for the protection of contact lenses from ocular pathogens. Many AMPs are in clinical trials for application in the therapy of local infections. There may be mentioned such preparations as: pexiganan (magainin analogue), MX-226 (based on indolicidin), NEUPREX (isolated from human BPI (bactericidal/permeability-increasing) protein), IB-367 (variant of porcine protegrin), P113 (based on histatin), daptomycin, polymyxins, as well as peptidomimetics. In the combat against systemic infections are used such peptides as: P113D (modified P113 peptide containing D-amino acids), colistin, peptoids, and peptides containing non-typical amino acids or non-peptide elements. AMPs are also used as antiprotozoal, antifungal, antitoxic and immunostimulatory agents. The limitations in the use of peptides in the treatment of infections, such as susceptibility to proteolysis, and resistance of microorganisms to the peptides, are also discussed. AMPs are a promising strategy in the fight against microbial infections.