title: A new Co(III)-hypocrellin B complex with enhanced photonuclease activity.
abstract: Hypocrellin B (HB), a naturally occurring photosensitizer, has been extensively and intensively studied as a promising photodynamic therapy (PDT) agent. In this work, a new Co(III) complex [Co(2)(HB)(tmp)(4)](4+) (tmp=3,4,7,8-tetramethyl-1,10-phenanthroline) was designed and synthesized with HB as bridging ligand and tmp as terminal ligand. [Co(2)HB(tmp)(4)](4+) exhibits improved water solubility, enhanced absorptivity in the phototherapeutic window, increased binding affinity and DNA photocleavage capability toward dsDNA with respect to HB. The photodynamic activity of [Co(2)(HB)(tmp)(4)](4+) stems from its (1)O(2) photosensitization ability, in sharp contrast to [Cu(2)(HB)(tmp)(2)](2+) which relies on superoxide anion radical (O(2)(-)) and hydroxyl radical (·OH) to photocleave DNA, though the both complexes possess similar electrochemical properties. The remarkable difference between the photodynamic mechanisms of [Co(2)(HB)(tmp)(4)](4+) and [Cu(2)(HB)(tmp)(2)](2+) was discussed in detail.
authors.affiliation: Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, PR China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Sun
authors.forename: Yuan-Jun
authors.initials: YJ
authors.lastname: Hou
authors.forename: Qian-Xiong
authors.initials: QX
authors.lastname: Zhou
authors.forename: Jing-Rong
authors.initials: JR
authors.lastname: Chen
authors.forename: Bao-Wen
authors.initials: BW
authors.lastname: Zhang
authors.forename: Xue-Song
authors.initials: XS
authors.lastname: Wang
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D053837:DNA Cleavage; D004270:DNA, Circular / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry; D017319:Photosensitizing Agents / Q000138:chemical synthesis / Q000737:chemistry*; D011809:Quinones / Q000737:chemistry*; D012995:Solubility; D013053:Spectrophotometry
chemical_list: D056831:Coordination Complexes; D004270:DNA, Circular; D017319:Photosensitizing Agents; D011809:Quinones; D017665:Hydroxyl Radical; D003035:Cobalt; D010569:Perylene; D004247:DNA; C427203:calf thymus DNA; C064522:hypocrellin B