title: Anion of hypericin is crucial to understanding the photosensitive features of the pigment.
abstract: Photosensitive behaviors of hypericin (HYP) have attracted much attention, because of HYP's great potential in photodynamic therapy. It has been found that HYP differs from homologous pigments, such as hypocrellin A (HA), in photosensitive features. For instance, despite the comparable triplet state quantum yields, HYP holds a much lower singlet oxygen yield than HA. To understand the unique photosensitive behaviors of HYP, time-dependent density functional theory is employed to calculate a series of excited-state properties of HYP and its anion (dominant in polar solvents), which are then compared with excited-state properties of HA. It is revealed that the stronger electron-donating power of HYP anion than that of HA is responsible for the HYP's photosensitive features.
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
authors.forename: Hong-Yu
authors.initials: HY
authors.lastname: Zhang
mesh_terms: D000838:Anions / Q000737:chemistry / Q000494:pharmacology; D000873:Anthracenes; D004583:Electrons; D015394:Molecular Structure; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D019800:Phenol; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000494:pharmacology*; D010860:Pigments, Biological / Q000737:chemistry* / Q000494:pharmacology*; D011809:Quinones / Q000737:chemistry; D026082:Singlet Oxygen
chemical_list: D000838:Anions; D000873:Anthracenes; D017319:Photosensitizing Agents; D010860:Pigments, Biological; D011809:Quinones; D026082:Singlet Oxygen; D019800:Phenol; D010569:Perylene; C004965:hypericin; C048388:hypocrellin A