title: Methods for the detection of reactive oxygen species employed in the identification of plant photosensitizers.
abstract: Over the past ten years, alternative methods for the rapid screening of PSs have been developed. In the present work, a study was undertaken to correlate the phototoxicity of plant extracts on either prokaryotic or eukaryotic cells, with the total oxidation status (TOS) as well as with their ability to produce1O2. Results demonstrated that the extracts containing PSs that were active either on eukaryotic cells or bacteria increased their TOS after illumination, and that there was a certain degree of positive correlation between the extract phototoxic efficacy and TOS levels. The production of1O2by the illuminated extracts was indirectly measured by the use of the fluorescence of "singlet oxygen sensor green", which is a method that has proved highly sensitive for such measurement.1O2was detectable only upon illumination of the most active extracts. In addition, the oxidation of tryptophan and was employed as a method capable of measuring ROS generated by both type I and II ROS reactions. However, it turned out to be not sensitive enough to detect the species generated by plant extracts. Results demonstrated that the TOS method, initially developed to measure the oxidant status in plasma, can be readily applied to plant extracts. Unlike the method used to detect1O2, the method employed for the detection of TOS proved to be accurate, since all the extracts that displayed a high phototoxic activity on either prokaryotic or eukaryotic cells, presented high TOS levels after illumination.
authors.affiliation: Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP)-CONICET-Hospital de Clínicas José de San Martín, Universidad de Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires CP1120AAF, Argentina.
authors.forename: Leandro
authors.initials: L
authors.lastname: Mamone
authors.affiliation: Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP)-CONICET-Hospital de Clínicas José de San Martín, Universidad de Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires CP1120AAF, Argentina.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Di Venosa
authors.affiliation: Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP)-CONICET-Hospital de Clínicas José de San Martín, Universidad de Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires CP1120AAF, Argentina.
authors.forename: Daniel
authors.initials: D
authors.lastname: Sáenz
authors.affiliation: Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP)-CONICET-Hospital de Clínicas José de San Martín, Universidad de Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires CP1120AAF, Argentina.
authors.forename: Alcira
authors.initials: A
authors.lastname: Batlle
authors.affiliation: Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP)-CONICET-Hospital de Clínicas José de San Martín, Universidad de Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires CP1120AAF, Argentina. Electronic address: adricasas@live.com.
authors.forename: Adriana
authors.initials: A
authors.lastname: Casas
mesh_terms: D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017319:Photosensitizing Agents / Q000737:chemistry / Q000302:isolation & purification*; D010936:Plant Extracts / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000302:isolation & purification*; D026082:Singlet Oxygen / Q000737:chemistry / Q000302:isolation & purification*; D014364:Tryptophan / Q000737:chemistry
chemical_list: D017319:Photosensitizing Agents; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D026082:Singlet Oxygen; D014364:Tryptophan
keywords: Free radicals; Photodynamic antimicrobial chemotherapy; Photodynamic therapy; Plants; Reactive oxygen species; Singlet oxygen