title: Photosensitization by the trypanocidal agent crystal violet. Type I versus type II reactions.
abstract: The photoreduction of crystal violet to a carbon-centered radical was detected directly by electron spin resonance (ESR) spectroscopy under anaerobic conditions. The linewidth (0.9 G) of this radical was less broad than the linewidth (11.0 G) of the free radical obtained in Trypanosoma cruzi incubations. No crystal violet radical could be detected under aerobic conditions. However, crystal violet was found to convert oxygen to superoxide anion and hydrogen peroxide in the presence of light. This superoxide anion and hydrogen peroxide formation was greatly enhanced by reducing agents such as NAD(P)H. In addition, irradiation of crystal violet did not generate detectable amounts of singlet oxygen.
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D005840:Gentian Violet / Q000494:pharmacology* / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000096:biosynthesis; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000096:biosynthesis / Q000378:metabolism; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D026082:Singlet Oxygen; D013481:Superoxides / Q000096:biosynthesis; D014344:Trypanocidal Agents / Q000494:pharmacology*; D014349:Trypanosoma cruzi / Q000187:drug effects* / Q000378:metabolism
chemical_list: D005609:Free Radicals; D011838:Radiation-Sensitizing Agents; D014344:Trypanocidal Agents; D013481:Superoxides; D026082:Singlet Oxygen; D009249:NADP; D006861:Hydrogen Peroxide; D005840:Gentian Violet; D010100:Oxygen