title: Kinetic study on the photostability of riboflavin in the presence of barbituric acid.
abstract: The photochemical fate of riboflavin (vitamin B2) in the presence of barbituric acid was examined employing polarographic detection of dissolved oxygen and steady-state and time-resolved spectroscopy. Under visible light, riboflavin reacts with barbituric acid--the latter being transparent to this type of photo-irradiation--via radicals and reactive oxygen species, such as singlet molecular oxygen [O2(1delta(g))] and superoxide radical anion, which are generated from the excited triplet state of the vitamin. As a result, both the vitamin and barbituric acid are photodegraded. Kinetic and mechanistic studies on the photoreactions of riboflavin in the presence of barbituric acid indicate the excellent quenching ability of the latter towards O2(1delta(g)).
authors.affiliation: Departamento de Química, Facultad de Ciencias Naturales, Universidad Nacional de La Patagonia San Juan Bosco, Comodoro Rivadavia, Argentina. isela@unpata.edu.ar
authors.forename: María Isela
authors.initials: MI
authors.lastname: Gutiérrez
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Fernández
authors.forename: Walter A
authors.initials: WA
authors.lastname: Massad
authors.forename: Norman Andino
authors.initials: NA
authors.lastname: García
mesh_terms: D001463:Barbiturates / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D015394:Molecular Structure; D010084:Oxidation-Reduction / Q000528:radiation effects; D010777:Photochemistry; D017382:Reactive Oxygen Species / Q000737:chemistry; D012256:Riboflavin / Q000737:chemistry*; D013053:Spectrophotometry
chemical_list: D001463:Barbiturates; D017382:Reactive Oxygen Species; D012256:Riboflavin; C032232:barbituric acid