title: Kinetics of the Reaction of Pyrogallol Red, a Polyphenolic Dye, with Nitrous Acid: Role of NO and NO2.
abstract: In the present work we studied the reaction under gastric conditions of pyrogallol red (PGR), a polyphenolic dye, with nitrous acid (HONO). PGR has been used as a model polyphenol due to its strong UV-visible absorption and its high reactivity towards reactive species (radicals and non-radicals, RS). The reaction was followed by UV-visible spectroscopy and high performance liquid chromatography (HPLC). A clear decrease of the PGR absorbance at 465 nm was observed, evidencing an efficient bleaching of PGR by HONO. In the initial stages of the reaction, each HONO molecule nearly consumed 2.6 PGR molecules while, at long reaction times, ca. 7.0 dye molecules were consumed per each reacted HONO. This result is interpreted in terms of HONO recycling. During the PGR-HONO reaction, nitric oxide was generated in the micromolar range. In addition, the rate of PGR consumption induced by HONO was almost totally abated by argon bubbling, emphasising the role that critical volatile intermediates, such as NO and/or nitrogen dioxide (NO2), play in the bleaching of this phenolic compound.
authors.affiliation: Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 8320000, Chile. estefahugo@gmail.com.
authors.forename: Estefania
authors.initials: E
authors.lastname: Hugo
authors.affiliation: Departamento de Farmacia, Facultad de Química, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile. jcreyes@uc.cl.
authors.forename: Jael
authors.initials: J
authors.lastname: Reyes
authors.affiliation: Departamento de Farmacia, Facultad de Química, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile. edmontup@uc.cl.
authors.forename: Elisa
authors.initials: E
authors.lastname: Montupil
authors.affiliation: Departamento de Farmacia, Facultad de Química, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile. rbridi@uc.cl.
authors.forename: Raquel
authors.initials: R
authors.lastname: Bridi
authors.affiliation: Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 8320000, Chile. eduardo.lissi@usach.cl.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Lissi
authors.affiliation: Laboratorio de Fisicoquímica Biológica, Facultad de Ciencias and Center for Free Radical and Biomedical Research, Universidad de la República, Montevideo 11400, Uruguay. denicola@fcien.edu.uy.
authors.forename: Ana
authors.initials: A
authors.lastname: Denicola
authors.affiliation: Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 8320000, Chile. maria.rubio@usach.cl.|Cedenna, Universidad de Santiago de Chile, Santiago 8320000, Chile. maria.rubio@usach.cl.
authors.forename: María Angélica
authors.initials: MA
authors.lastname: Rubio
authors.affiliation: Departamento de Farmacia, Facultad de Química, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile. clopezr@uc.cl.
authors.forename: Camilo
authors.initials: C
authors.lastname: López-Alarcón
mesh_terms: D002851:Chromatography, High Pressure Liquid; D009569:Nitric Oxide / Q000737:chemistry; D009585:Nitrogen Dioxide / Q000737:chemistry; D009608:Nitrous Acid / Q000737:chemistry*; D011748:Pyrogallol / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D011748:Pyrogallol; D009569:Nitric Oxide; C058731:pyrogallol sulfonphthalein; D009585:Nitrogen Dioxide; D009608:Nitrous Acid
keywords: kinetics; nitric oxide; nitrogen dioxide; nitrous acid; phenols; pyrogallol red