title: Peridinin as the major biological carotenoid quencher of singlet oxygen in marine algae Gonyaulax polyedra.
abstract: Carotenoids in light-harvesting proteins and reaction centers increase the overall efficiency of photosynthesis by transferring absorbed light energy to chlorophylls. Peridinin and beta-carotene were isolated from Gonyaulax polyedra in a one-step purification protocol using the preparative circular chromatography (Chromatotron), performed on silica gel under N(2) atmosphere and n-hexane/acetone 8:2 as mobile phase and characterized by extensive (1)H NMR, infrared, and electrospray ionization mass spectrometry analyses. The quenching of singlet molecular oxygen [O(2) ((1)Delta(g))] was evaluated by NIR-emission assays using singlet oxygen generated by sensitization of either perinaphthenone or methylene blue. The NIR-emission assay showed that peridinin quench as singlet oxygen (k(q) = 9.5 x 10(8) M(-1) s(-1)) 5-fold less efficiently than beta-carotene (52 x 10(8) M(-1) s(-1)). A method, based on the use of high-performance liquid chromatography with UV-VIS detection, was then developed for the sensitive quantification of peridinin (55% of total carotenoids) and beta-carotene (4.1% of total carotenoids). Thus, since peridinin is 10-fold more abundant than beta-carotene, it is expected to be the major protector against the deleterious effects of O(2) ((1)Delta(g)) in Gonyaulax polyedra.
authors.affiliation: Departamento de Bioquímica, Universidade de São Paulo, São Paulo, CEP 05599-970, Brazil.
authors.forename: E
authors.initials: E
authors.lastname: Pinto
authors.forename: L H
authors.initials: LH
authors.lastname: Catalani
authors.forename: N P
authors.initials: NP
authors.lastname: Lopes
authors.forename: P
authors.initials: P
authors.lastname: Di Mascio
authors.forename: P
authors.initials: P
authors.lastname: Colepicolo
mesh_terms: D000818:Animals; D002338:Carotenoids / Q000737:chemistry / Q000378:metabolism*; D004141:Dinoflagellida / Q000737:chemistry / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*
chemical_list: C016040:peridinin; D002338:Carotenoids; D010100:Oxygen