title: Approaches to unravel pathways of reactive oxygen species in the photoinactivation of bacteria induced by a dicationic fulleropyrrolidinium derivative.
abstract: The photodynamic mechanism sensitized by N,N-dimethyl-2-[4-(3-N,N,N-trimethylammoniopropoxy)phenyl]fulleropyrrolidinium (DPC602+) was investigated in Staphylococcus aureus cells. Different experimental conditions were used to detect reactive oxygen species (ROS) in S. aureus cell suspensions. First, a photoinactivation of 4 log decrease of S. aureus viability was chosen using 0.5μM DPC602+and 15min irradiation. An anoxic atmosphere indicated that oxygen was required for an effective photoinactivation. Also, photoprotection was found in the presence of sodium azide, whereas the photocytotoxicity induced by DPC602+increased in D2O. The addition of diazabicyclo[2.2.2]octane or d-mannitol produced a reduction in the S. aureus photokilling. Moreover, singlet molecular oxygen, O2(1Δg), was detected by the reaction with 9,10-dimethylanthracene into the S. aureus cells. A decrease in the photoinactivation of S. aureus was observed in the presence of β-nicotinamide adenine dinucleotide reduced form, which was dependent on the NADH concentration. Therefore, under aerobic condition the photocytotoxicity activity induced by DPC602+was mediated by mainly a contribution of type II process. Moreover, photoinactivation of S. aureus was possible with DPC602+in the presence of azide anions under anoxic condition. However, these conditions were not effective to photoinactivate Escherichia coli. On the other hand, the addition of potassium iodide produced an increase in the photokilling of bacteria, depending on the KI concentration and irradiation times. The formation of reactive iodine species may be contributing to inactivate S. aureus cells photoinduced by DPC602+.
authors.affiliation: Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36 Km 601, X5804BYA Río Cuarto, Córdoba, Argentina.
authors.forename: Natalia S
authors.initials: NS
authors.lastname: Gsponer
authors.affiliation: Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36 Km 601, X5804BYA Río Cuarto, Córdoba, Argentina.
authors.forename: Maximiliano L
authors.initials: ML
authors.lastname: Agazzi
authors.affiliation: Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36 Km 601, X5804BYA Río Cuarto, Córdoba, Argentina.
authors.forename: Mariana B
authors.initials: MB
authors.lastname: Spesia
authors.affiliation: Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36 Km 601, X5804BYA Río Cuarto, Córdoba, Argentina. Electronic address: edurantini@exa.unrc.edu.ar.
authors.forename: Edgardo N
authors.initials: EN
authors.lastname: Durantini
mesh_terms: D000873:Anthracenes / Q000737:chemistry; D002413:Cations, Divalent / Q000737:chemistry; D015687:Cell Hypoxia / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000472:pathogenicity / Q000528:radiation effects; D037741:Fullerenes / Q000737:chemistry* / Q000494:pharmacology; D008027:Light; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D011193:Potassium Iodide / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry* / Q000302:isolation & purification; D019810:Sodium Azide / Q000737:chemistry; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000472:pathogenicity / Q000528:radiation effects
chemical_list: D000873:Anthracenes; D002413:Cations, Divalent; C000626003:DPC60 compound; D037741:Fullerenes; D000644:Quaternary Ammonium Compounds; D017382:Reactive Oxygen Species; D011193:Potassium Iodide; D019810:Sodium Azide; C029126:9,10-dimethylanthracene; D010100:Oxygen
keywords: Fullerene; Photodynamic inactivation; Photosensitizer; ROS; Staphylococcus aureus