title: Chelation of hypocrellin B with zinc ions with electron paramagnetic resonance (EPR) evidence of the photodynamic activity of the resulting chelate.
abstract: Hypocrellin B (HB), a perylenequinone derivative, is an efficient phototherapeutic agent. The chelation of HB with Zinc ions (Zn2+) results in a metal chelate (Zn-HB) which exhibits considerable absorption (lambda max = 612 nm) in the phototherapeutic window. The structure of this chelate has been characterized by UV-Vis, IR and mass spectra. The redox potentials of the Zn-HB chelate were Eox = +1.1 V (vs. SCE) and Ere = -0.7 V (vs. SCE) as measured using the circle volt curve. The quantum yield of singlet oxygen generated by the Zn-HB chelate was 0.86, which both the electron spin trap (EPR) method and the chemical trap method show to be about 0.1 higher than that of its parent compound HB. In irradiated oxygen-saturated solutions of Zn-HB chelate, superoxide radical anions and hydroxyl radicals were detected by EPR spectroscopy using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin-trapping agent.
authors.affiliation: Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100080, P.R. China.
authors.forename: C
authors.initials: C
authors.lastname: Tian
authors.forename: S
authors.initials: S
authors.lastname: Xu
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Shen
authors.forename: M
authors.initials: M
authors.lastname: Zhang
authors.forename: T
authors.initials: T
authors.lastname: Shen
mesh_terms: D002614:Chelating Agents; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D017665:Hydroxyl Radical / Q000737:chemistry; D066298:In Vitro Techniques; D015394:Molecular Structure; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000494:pharmacology*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000494:pharmacology*; D011809:Quinones / Q000737:chemistry* / Q000494:pharmacology*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013055:Spectrophotometry, Infrared; D013481:Superoxides / Q000737:chemistry; D015032:Zinc
chemical_list: D002614:Chelating Agents; D017319:Photosensitizing Agents; D011809:Quinones; D013481:Superoxides; D017665:Hydroxyl Radical; D010569:Perylene; D015032:Zinc; C064522:hypocrellin B