title: The mechanisms of ROS-photogeneration by berberine, a natural isoquinoline alkaloid.
abstract: The reactive oxygen species (ROS)-photogenerating mechanisms of berberine (BER) have been elucidated based on the time-dependent density functional theory calculated triplet excited (T(1)) state characters in explicit solvent models. The lowest triplet excitation energy of BER is obtained for the first time. Mechanistic analysis reveals the strong dependence of 1O2 and O2(.-) generation on the solvent polarity. Through direct energy transfer pathway from T(1) state BER to 3O2, 1O2 can be photogenerated both in benzene and ethanol. Nevertheless, O2(.-) can be given birth to only in ethanol through two pathways, i.e., direct electron transfer from T(1) state BER and electron transfer from BER(.-) (formed through autoionization reactions) to 3O2. The findings also provide clues to explaining the much higher 1O2-yield of BER in nonpolar than in polar solvents.
authors.affiliation: Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Center for Advanced Study, Shandong University of Technology, Zibo 255049, PR China.
authors.forename: Liang
authors.initials: L
authors.lastname: Shen
authors.forename: Hong-Fang
authors.initials: HF
authors.lastname: Ji
mesh_terms: D001599:Berberine / Q000737:chemistry*; D004735:Energy Transfer; D008956:Models, Chemical; D055668:Photochemical Processes; D017319:Photosensitizing Agents / Q000737:chemistry*; D011789:Quantum Theory; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry
chemical_list: D017319:Photosensitizing Agents; D017382:Reactive Oxygen Species; D012997:Solvents; D001599:Berberine