Caffeic Acid Inhibits the Formation of 7-Carboxyheptyl Radicals from Oleic Acid under Flavin Mononucleotide Photosensitization by Scavenging Singlet Oxygen and Quenching the Excited State of Flavin MononucleotideReportar como inadecuado




Caffeic Acid Inhibits the Formation of 7-Carboxyheptyl Radicals from Oleic Acid under Flavin Mononucleotide Photosensitization by Scavenging Singlet Oxygen and Quenching the Excited State of Flavin Mononucleotide - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Department of Chemistry, Wakayama Medical University, 580 Mikazura, Wakayama 641-0011, Japan





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Abstract We examined the effects of caffeic acid CA and related compounds on 7-carboxyheptyl radical formation. This analysis was performed using a standard D2O reaction mixture containing 4.3 mM oleic acid, 25 μM flavin mononucleotide FMN, 160 mM phosphate buffer pH 7.4, 10 mM cholic acid, 100 mM α-4-pyridyl-1-oxide-N-tert-butylnitrone, and 1 mM FeSO42NH42 during irradiation with 7.8 J-cm2 at 436 nm. 7-Carboxyheptyl radical formation was inhibited by CA, catechol, gallic acid, chlorogenic acid, ferulic acid, noradrenalin, 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, and 4-hydroxybenzoic acid. Quinic acid, benzoic acid, and p-anisic acid had no effect on radical formation. These results suggest that a phenol moiety is essential for these inhibitory effects. The fluorescence intensity of FMN decreased by 69% ± 2% after CA addition, suggesting that CA quenches the singlet excited state of FMN. When 1 mM CA was added to a standard reaction mixture containing 25 μM FMN, 140 mM phosphate buffer pH 7.4, and 10 mM 4-oxo-2,2,6,6-tetramethylpiperidine, the electron spin resonance signal of 4-oxo-2,2,6,6-tetramethylpiperidinooxy disappeared. This finding suggests that singlet oxygen was scavenged completely by CA. Therefore, CA appears to inhibit 7-carboxyheptyl radical formation by scavenging singlet oxygen and quenching the excited state of FMN. View Full-Text

Keywords: caffeic acid; FMN; oleic acid; photosensitization reaction; 7-carboxyheptyl radical; singlet oxygen; phenol; spin trapping; HPLC-ESR caffeic acid; FMN; oleic acid; photosensitization reaction; 7-carboxyheptyl radical; singlet oxygen; phenol; spin trapping; HPLC-ESR





Autor: Marie Asano and Hideo Iwahashi *

Fuente: http://mdpi.com/



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