Mycosis, caused by both filamentous fungi and pathogenic yeasts is a major concern nowadays especially in the immunocompromised patient population. The emergence of pathogenic fungi resistant to current therapies in the last few decades has intensified the search for new antifungals like cationic peptides, which are the key components of innate defense mechanism. The review provides an inventory of different peptides from a diverse array of organisms from bacteria to mammals with proven antifungal activity, their therapeutic options and also about those which are in various stages of preclinical development. Literature, on the total and semi-synthetic variants of the parent peptides that exhibit an improved antifungal activity is also reviewed.
"A prominent group of bioactive lipopeptides produced by Bacillus species is constituted by iturins, surfactins and lichenysins (Bonmatin et al. 2003). Iturins produced by Bacillus subtilis are a prominent group of cyclic peptidolipids with seven alpha-amino acids and one beta-amino fatty acid (Ajesh and Sreejith 2009). They exhibit strong antifungal activities against various varieties of pathogenic yeasts and fungi, and their activity is related to their interaction with the cytoplasmic membrane of target cells, leading to an increase in K+ permeability (Maget-Dana and Peypoux 1994). "
[Show abstract][Hide abstract] ABSTRACT: This study was performed to isolate and characterize novel antifungal peptide from Bacillus cereus.
Elucidation of its chemical structure was carried out by electrospray ionization mass spectra (ESI-MS) and Fourier transform infrared spectroscopy (FT-IR). The compound is a cyclic heptapeptide and composed of amino acids, Leu-Asp-Val-Leu-Leu-Leu-Leu. The in vitro activity of Kannurin against various pathogenic yeasts was assessed by CLSI M27-A and molds by M38-A. It demonstrated broad-spectrum, fungicidal activity against clinically relevant yeasts and molds. Kannurin exhibited low haemolytic activity and remained active over a wide pH and temperature range. In addition, Kannurin did not bind with melanin particles and was as active in inhibiting biofilms.
An antifungal surfactin-like lipopeptide produced by Bacillus cereus strain AK1 was purified and chemically characterised. We propose to name this lipopeptide compound Kannurin. To our knowledge, this is the first report of Bacillus cereus producing surfactin like lipopeptide antibiotic with stronger antifungal activity.
Our results provide a valuable contribution towards a better understanding of the lipopeptide of Bacillus cereus. Moreover, it raises the possibility of using as an alternative antibiotic in clinical medicine. This article is protected by copyright. All rights reserved.
"Besides these problems, the emergence of strains resistant to current therapeutic agents makes essential and urgent the identification of new antifungal compounds . Despite numerous reports on the occurrence and activity of proteins and antimicrobial peptides originated from plant, some have already been successfully tested as transgenes to confer resistance to plants against fungi and/or insects , only a few have been evaluated for therapeutic potential in human mycoses . The search for new antifungal compounds from plants became extremely urgent considering the spread of invasive mycoses, particularly in immunocompromised patients, caused by pathogenic fungi or in plants by soil fungi (e.g., Alternaria, Curvularia and Rhizopus), before considered as fungi of low virulence , and which are currently being considered as emerging pathogens . "
[Show abstract][Hide abstract] ABSTRACT: Ureases (EC 188.8.131.52) are metalloenzymes that hydrolyze urea into ammonia and CO(2). These proteins have insecticidal and fungicidal effects not related to their enzymatic activity. The insecticidal activity of urease is mostly dependent on the release of internal peptides after hydrolysis by insect digestive cathepsins. Jaburetox is a recombinant version of one of these peptides, expressed in Escherichia coli. The antifungal activity of ureases in filamentous fungi occurs at submicromolar doses, with damage to the cell membranes. Here we evaluated the toxic effect of Canavalia ensiformis urease (JBU) on different yeast species and carried out studies aiming to identify antifungal domain(s) of JBU. Data showed that toxicity of JBU varied according to the genus and species of yeasts, causing inhibition of proliferation, induction of morphological alterations with formation of pseudohyphae, changes in the transport of H(+) and carbohydrate metabolism, and permeabilization of membranes, which eventually lead to cell death. Hydrolysis of JBU with papain resulted in fungitoxic peptides (∼10kDa), which analyzed by mass spectrometry, revealed the presence of a fragment containing the N-terminal sequence of the entomotoxic peptide Jaburetox. Tests with Jaburetox on yeasts and filamentous fungi indicated a fungitoxic activity similar to ureases. Plant ureases, such as JBU, and its derived peptides, may represent a new alternative to control medically important mycoses as well as phytopathogenic fungi, especially considering their potent activity in the range of 10(-6)-10(-7)M.
"Taking into consideration a continual need to develop pathogen-resistant varieties, plant AMPs show high potential for elaboration of innovative plant disease control measures. Moreover , thanks to their broad-spectrum activity, lack of microbial resistance mechanisms and high efficacy in model systems, they represent attractive templates for designing new pharmaceuticals   . Wild plants and weeds, whose perfect adaptation to changing environments implies enhanced disease resistance, provide a valuable source of antimicrobials. "
[Show abstract][Hide abstract] ABSTRACT: Three novel antimicrobial peptides designated ToAMP1, ToAMP2 and ToAMP3 were purified from Taraxacum officinale flowers. Their amino acid sequences were determined. The peptides are cationic and cysteine-rich and consist of 38, 44 and 42 amino acid residues for ToAMP1, ToAMP2 and ToAMP3, respectively. Importantly, according to cysteine motifs, the peptides are representatives of two novel previously unknown families of plant antimicrobial peptides. ToAMP1 and ToAMP2 share high sequence identity and belong to 6-Cys-containing antimicrobial peptides, while ToAMP3 is a member of a distinct 8-Cys family. The peptides were shown to display high antimicrobial activity both against fungal and bacterial pathogens, and therefore represent new promising molecules for biotechnological and medicinal applications.
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