title: Natural anthraquinones probed as Type I and Type II photosensitizers: singlet oxygen and superoxide anion production.
abstract: The photosensitizing properties of six anthraquinones (AQs): soranjidiol (1), soranjidiol-1-methyl ether (2), rubiadin (3), rubiadin-1-methyl ether (4), damnacanthal (5) and damnacanthol (6), isolated from leaves and stems of Heterophyllaea pustulata Hook. f. (Rubiaceae) were studied. By means of photobiological and photophysical methods in vitro, the type of photosensitization that these metabolites are capable of producing was determined. Whereas the photosensitized generation of superoxide anion radical (O(2)(-)) (Type I) was evaluated in leukocyte suspensions, singlet molecular oxygen ((1)O(2)) production (Type II) was examined in organic solution. In addition, the quantum yield of (1)O(2) (Phi) in chloroform was measured for those AQs that generate it. It was established that 4 behaves exclusively as a Type I photosensitizer. By contrast, the others AQs act by both types of mechanisms, among which 5 showed the largest Phi of (1)O(2).
authors.affiliation: Farmacognosia, Departamento de Farmacia, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba (IMBIV-CONICET), Ciudad Universitaria, 5000 Córdoba, Argentina.
authors.forename: Susana C Núñez
authors.initials: SC
authors.lastname: Montoya
authors.forename: Laura R
authors.initials: LR
authors.lastname: Comini
authors.forename: Martín
authors.initials: M
authors.lastname: Sarmiento
authors.forename: Cecilia
authors.initials: C
authors.lastname: Becerra
authors.forename: Inés
authors.initials: I
authors.lastname: Albesa
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Argüello
authors.forename: José L
authors.initials: JL
authors.lastname: Cabrera
mesh_terms: D000838:Anions / Q000737:chemistry; D000880:Anthraquinones / Q000737:chemistry*; D006801:Humans; D015394:Molecular Structure; D009000:Monocytes / Q000737:chemistry / Q000378:metabolism; D017319:Photosensitizing Agents / Q000737:chemistry*; D026082:Singlet Oxygen / Q000737:chemistry* / Q000378:metabolism*; D013057:Spectrum Analysis; D013481:Superoxides / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D000838:Anions; D000880:Anthraquinones; D017319:Photosensitizing Agents; D013481:Superoxides; D026082:Singlet Oxygen