The phototoxicity of phenothiazinium derivatives against Escherichia coli and Staphylococcus aureus.
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.
Phoenix
D A
DA
Department of Forensic and Investigative Science, University of Central Lancashire, Preston PR1 2HE, UK. daphoenix@uclan.ac.uk
Sayed
Z
Z
Hussain
S
S
Harris
F
F
Wainwright
M
M
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*
D000900:Anti-Bacterial Agents; D004396:Coloring Agents; D010640:Phenothiazines; D017319:Photosensitizing Agents