title: Phenothiaziniums as putative photobactericidal agents for red blood cell concentrates.
abstract: The antibacterial activities of Methylene Blue and several of its congeners were measured against Yersinia enterocolitica, a gram-negative pathogen known to exhibit significant growth at 4 degrees C and thus constituting a threat to red blood cell concentrates which are stored at this temperature. None of the derivatives was highly active in dark conditions, as expected, but on illumination using a lamp emitting light in the waveband 615-645 nm, considerable bactericidal activity was noted using similar photosensitizer concentrations to those used elsewhere to inactivate blood-borne viruses. Two novel compounds in this area, the phenothiazinium New Methylene Blue N and the phenoxazinium Brilliant Cresyl Blue, exhibited bactericidal activity at lower concentrations than both of the established phenothiaziniums, Methylene Blue and Toluidine Blue O and the recently published blood photovirucidal agent 1,9-Dimethyl Methylene Blue. The photoactivity of these compounds was undiminished in the presence of red blood cells.
authors.affiliation: Centre for Forensic Science, University of Central Lancashire, Preston, UK. MWainwright@uclan.ac.uk
authors.forename: M
authors.initials: M
authors.lastname: Wainwright
authors.forename: D A
authors.initials: DA
authors.lastname: Phoenix
authors.forename: T E
authors.initials: TE
authors.lastname: Smillie
authors.forename: D R
authors.initials: DR
authors.lastname: Wareing
mesh_terms: D001771:Blood Banks; D004396:Coloring Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004912:Erythrocytes; D017053:Infection Control; D008027:Light; D008751:Methylene Blue / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D010078:Oxazines / Q000494:pharmacology*; D013696:Temperature; D015008:Yersinia enterocolitica / Q000187:drug effects*
chemical_list: D004396:Coloring Agents; D004791:Enzyme Inhibitors; D010078:Oxazines; C035184:new methylene blue; C006797:Brilliant Cresyl Blue; D008751:Methylene Blue