Search results for "DOPAC"
showing 5 items of 5 documents
Reactions of Flavonoids with o‑Quinones Interfere with the Spectrophotometric Assay of Tyrosinase Activity
2016
Flavonoids are important food components with antioxidant properties and many of them have been described as tyrosinase inhibitors. Oxidation of quercetin, kaempferol, morin, catechin, and naringenin by mushroom tyrosinase and their influence on the oxidation of l-dopa and l-tyrosine was studied. Reaction rates measured spectrophotometrically and by oxygen consumption differed substantially. All tested flavonoids reacted with 4-tert-butyl-o-benzoquinone and/or 4-methyl-o-benzoquinone, although at different rates. These reactions generated products whose UV-vis spectra either overlapped or did not overlap with the spectrum of dopachrome. They therefore strongly influence the kinetic analysis…
Redox reaction between amino-(3,4-dihydroxyphenyl)methyl phosphonic acid and dopaquinone is responsible for the apparent inhibitory effect on tyrosin…
2002
Amino-(3,4-dihydroxyphenyl)methyl phosphonic acid, the phosphonic analog of 3,4-dihydroxyphenylglycine, had been previously reported as a potent inhibitor of tyrosinase. The mechanism of the apparent enzyme inhibition by this compound has now been established. Amino-(3,4-dihydroxyphenyl)methyl phosphonic acid turned out to be a substrate and was oxidized to o-quinone, which evolved to a final product identified as 3,4-dihydroxybenzaldehyde, the same as for 3,4-dihydroxyphenylglycine. Monohydroxylated compounds (amino-(3-hydroxyphenyl)methyl phosphonic acid and amino-(4-hydroxyphenyl)methyl phosphonic acid) were not oxidized, neither was 4-hydroxy-l-phenylglycine. However, the relatively hig…
Efectos conductuales y neuroquímicos del consumo de éxtasis y cocaína en ratones adolescentes.
2009
La 3,4-metilendioximetanfetamina (MDMA), una sustancia popularmente conocida como éxtasis, es una droga ilícita consumida habitualmente por adolescentes y adultos jóvenes. Además, el policonsumo es una práctica habitual entre los usuarios de la MDMA, siendo la cocaína una de las drogas más frecuentemente asociadas a esta sustancia. El objetivo del presente trabajo fue evaluar los efectos a corto y largo plazo que se producen tras la administración de la MDMA (5, 10, o 20 mg/kg) sola o en combinación con cocaína (25 mg/kg) en ratones adolescentes. En el estudio sobre el efecto agudo, observamos que ambas drogas administradas individual o simultáneamente incrementan la actividad motora. La do…
Biocatalytic formation of synthetic melanin: The role of vanadium haloperoxidases, L-DOPA and iodide
2011
The vanadium haloperoxidase (V-HPO) enzyme, extracted from the brown alga Laminaria saccharina, is able to catalyze the formation of a black precipitate, using as precursor the amino acid L-dopa in the presence of hydrogen peroxide and iodide, in one-pot synthesis. The L-dopa oxidation is a multistep reaction with a crucial role played by the iodide in the enzyme catalyzed peroxidative production of dopachrome, a well known intermediate in the synthesis of melanin. Dopachrome is then converted to a synthetic form of melanin through a polymerization reaction. Factors, such as buffer composition and pH, influence significantly the reaction first steps, but further steps of melanin production …
Implicación del sistema serotoninérgico y dopaminérgico en los efectos reforzantes de la MDMA
2012
La adolescencia constituye un periodo de especial vulnerabilidad al consumo de drogas, siendo los adolescentes los principales consumidores de 3,4- metilendioximetanfetamina (MDMA), un derivado anfetamínico con potencial adictivo. El objetivo del presente trabajo es evaluar el papel de los sistemas dopaminérgico y serotoninérgico en las propiedades reforzantes de la MDMA y en la vulnerabilidad a la recaída en su consumo. En concreto, hemos estudiado la implicación de estos sistemas de neurotransmisión en la adquisición, expresión y reinstauración del condicionamiento de preferencia de lugar (CPL) inducido por MDMA en ratones adolescentes. Para ello utilizamos diferentes agonistas y antagoni…