title: Photosensitized xanthone-based oxidation of guanine and its repair: a laser flash photolysis study.
abstract: The photosensitized oxidation of guanine (G) by the triplet state of xanthone (XT) and the repair for photo-damaged G(-H)(·) by ferulic acid (FCA) were investigated using the laser flash photolysis technique. The rate constants of the reaction of triplet state of XT with G and with FCA were determined as 4.5×10(9) and 8.0×10(9) L mol(-1) s(-1), respectively. Laser exposure was performed on the N(2)-saturated acetonitrile/water (v/v, 1:1) solution containing G, XT and FCA. The transient absorption spectra indicated that the triplet state of XT first reacted with G predominantly to form the oxidized radical G(-H)(·). The radical G(-H)(·) was rapidly repaired by FCA, and the rate constant for the repair reaction was determined as 1.1×10(9) L mol(-1) s(-1). These results demonstrated that non-enzymatic repair is a feasible method for repairing photosensitized DNA bases oxidation.
authors: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors: Ruizhi
authors: R
authors: Tang
authors: Peng
authors: P
authors: Zhang
authors: Haixia
authors: H
authors: Li
authors: Yancheng
authors: Y
authors: Liu
authors: Wenfeng
authors: W
authors: Wang
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D003373:Coumaric Acids / Q000737:chemistry / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects* / Q000528:radiation effects*; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D006147:Guanine / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D007834:Lasers; D010084:Oxidation-Reduction / Q000187:drug effects / Q000528:radiation effects; D010782:Photolysis; D017319:Photosensitizing Agents / Q000494:pharmacology*; D013057:Spectrum Analysis; D014867:Water / Q000737:chemistry; D044004:Xanthones / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000097:Acetonitriles; D003373:Coumaric Acids; D005609:Free Radicals; D017319:Photosensitizing Agents; D044004:Xanthones; D014867:Water; D006147:Guanine; C009689:xanthone; C004999:ferulic acid; C032159:acetonitrile