title: Mechanism of action of novel synthetic dodecapeptides against Candida albicans.
abstract: BACKGROUND
  Three de novo designed low molecular weight cationic peptides (IJ2, IJ3 and IJ4) containing an unnatural amino acid α,β-didehydrophenylalanine (∆Phe) exhibited potent antifungal activity against fluconazole (FLC) sensitive and resistant clinical isolates of Candida albicans as well as non-albicans and other yeast and filamentous pathogenic fungi. In the present study, their synthesis, susceptibility of different fungi and the mechanism of anti-candidal action have been elucidated.
  
  
  METHODS
  The antimicrobial peptides (AMPs) were synthesized by solid-phase method and checked for antifungal activity against different yeasts and fungi by broth microdilution method. Anti-candidal mode of action of the peptides was investigated through detecting membrane permeabilization by confocal microscopy, Reactive Oxygen Species (ROS) generation by fluorometry, apoptosis and necrosis by flow cytometry and cell wall damage using Scanning and Transmission Electron Microscopy.
  
  
  CONCLUSIONS
  The MIC of the peptides against C. albicans and other yeast and filamentous fungal pathogens ranged between 3.91 and 250μM. All three peptides exhibited effect on multiple targets in C. albicans including disruption of cell wall structures, compromised cell membrane permeability leading to their enhanced entry into the cells, accumulation of ROS and induction of apoptosis. The peptides also showed synergistic effect when used in combination with fluconazole (FLC) and caspofungin (CAS) against C. albicans.
  
  
  CONCLUSIONS
  The study suggests that the AMPs alone or in combination with conventional antifungals hold promise for the control of fungal pathogens, and need to be further explored for treatment of fungal infections.
authors.affiliation: Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors.forename: Indresh Kumar
authors.initials: IK
authors.lastname: Maurya
authors.forename: Chaitanya Kumar
authors.initials: CK
authors.lastname: Thota
authors.forename: Jyotsna
authors.initials: J
authors.lastname: Sharma
authors.forename: Santosh Genba
authors.initials: SG
authors.lastname: Tupe
authors.forename: Preeti
authors.initials: P
authors.lastname: Chaudhary
authors.forename: Manoj Kumar
authors.initials: MK
authors.lastname: Singh
authors.forename: Indu Shekhar
authors.initials: IS
authors.lastname: Thakur
authors.forename: Mukund
authors.initials: M
authors.lastname: Deshpande
authors.forename: Rajendra
authors.initials: R
authors.lastname: Prasad
authors.forename: Virander Singh
authors.initials: VS
authors.lastname: Chauhan
mesh_terms: D000935:Antifungal Agents / Q000138:chemical synthesis* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002176:Candida albicans / Q000187:drug effects*; D000077336:Caspofungin; D002463:Cell Membrane Permeability / Q000187:drug effects; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D004357:Drug Synergism; D054714:Echinocandins / Q000494:pharmacology; D015725:Fluconazole / Q000494:pharmacology; D006461:Hemolysis / Q000187:drug effects; D055666:Lipopeptides; D009336:Necrosis / Q000188:drug therapy / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis* / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D054714:Echinocandins; D055666:Lipopeptides; D010455:Peptides; D017382:Reactive Oxygen Species; D015725:Fluconazole; D000077336:Caspofungin
keywords: ABC; ATP-Binding Cassette; Antifungal peptide; Antimicrobial peptide (AMP); Apoptosis; Candida albicans; FICI; Fraction Inhibitory Concentration Index; MDR; MFS; Major Facilitator Superfamily; Multidrug Resistance; ROS; Reactive Oxygen Species; Reactive Oxygen Species (ROS); SEM; Scanning Electron Microscopy; TEM; Transmission Electron Microscopy