title: The phototoxicity of phenothiazinium derivatives against Escherichia coli and Staphylococcus aureus.
abstract: Phenothiazinium dyes, and derivatives, were tested for toxicity to Escherichia coli and Staphylococcus aureus. The dyes were generally lipophilic (log P>1) and showed inherent dark toxicity (minimum lethal concentrations: 3.1-1000 microM). Dye illumination (total light dose of 3.15 J cm(-1) over 30 min) led to up to eight-fold reductions in minimum lethal concentrations. Most of the illuminated dyes showed significant relative singlet oxygen yields (phi'delta: 0.18-1.35) suggesting a type II mechanism of generating a phototoxic response. Although generally up to six-fold more effective against S. aureus, the dyes tested efficiently killed E. coli and may be of particular use in combating Gram-negative pathogens.
authors.affiliation: Department of Forensic and Investigative Science, University of Central Lancashire, Preston PR1 2HE, UK. daphoenix@uclan.ac.uk
authors.forename: D A
authors.initials: DA
authors.lastname: Phoenix
authors.forename: Z
authors.initials: Z
authors.lastname: Sayed
authors.forename: S
authors.initials: S
authors.lastname: Hussain
authors.forename: F
authors.initials: F
authors.lastname: Harris
authors.forename: M
authors.initials: M
authors.lastname: Wainwright
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D004396:Coloring Agents / Q000737:chemistry / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects*; D006801:Humans; D010640:Phenothiazines / Q000737:chemistry / Q000494:pharmacology*; D018462:Photobiology; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D004396:Coloring Agents; D010640:Phenothiazines; D017319:Photosensitizing Agents