title: Fluorogenic Ubiquinone Analogue for Monitoring Chemical and Biological Redox Processes.
abstract: We report herein the synthesis and characterization of a fluorogenic analogue of ubiquinone designed to reversibly report on redox reactions in biological systems. The analogue, H2B-Q, consists of the redox-active quinone segment found in ubiquinone, 2,3-dimethoxy-1,4-benzoquinone, coupled to a boron-dipyrromethene (BODIPY) fluorophore segment that both imparts lipophilicity in lieu of the isoprenyl tail of ubiquinone, and reports on redox changes at the quinone/quinol segment. Redox sensing is mediated by a photoinduced electron transfer intramolecular switch. In its reduced dihydroquinone form, H2B-QH2 is highly emissive in nonpolar media (quantum yields 55-66%), while once oxidized, the resulting quinone H2B-Q emission is suppressed. Cyclic voltammetry of H2B-Q shows two reversible, 1-electron reduction peaks at -1.05 V and -1.37 V (vs ferrocene) on par with those of ubiquinone. Chemical reduction of H2B-Q by NaBH4 resulted in >200 fold emission enhancement. H2B-QH2 is shown to react with peroxyl radicals, a form of reactive oxygen species (ROS) as well as to cooperatively interact with chromanol (the active segment of α-tocopherol). Kinetic analysis further shows the antioxidant reactivity of the nonfluorescent intermediate semiquinone. We anticipate that the H2B-Q/H2B-QH2 off/on reversible couple may serve as a tool to monitor chemical redox processes in real-time and in a noninvasive manner.
authors: Department of Chemistry and Center for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University , 801 Sherbrooke Street West, Montreal, Quebec H3G 0B8, Canada.
authors: Lana E
authors: LE
authors: Greene
authors: Department of Chemistry and Center for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University , 801 Sherbrooke Street West, Montreal, Quebec H3G 0B8, Canada.
authors: Robert
authors: R
authors: Godin
authors: Department of Chemistry and Center for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University , 801 Sherbrooke Street West, Montreal, Quebec H3G 0B8, Canada.
authors: Gonzalo
authors: G
authors: Cosa
mesh_terms: D001896:Boron Compounds / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D014451:Ubiquinone / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D005456:Fluorescent Dyes; D014451:Ubiquinone