title: Radiolysis of kaempferol in water/methanol mixtures. Evaluation of antioxidant activity of kaempferol and products formed.
abstract: Oxidative reaction between hydroxymethyl radical ((*)CH(2)OH) and kaempferol, in methanol and methanol/water mixtures, was studied by gamma-radiolysis using a (60)Co source. Radiolysis was performed with concentrations and doses ranging from 5 x 10(-)(5) M to 5 x 10(-)(3) M and from 0.5 kGy to 14 kGy, respectively. Kaempferol degradation was followed by HPLC. Results showed that (*)CH(2)OH reacts with kaempferol at the 3-OH group and produces two depsides (K1 and K2) and other products including K3. K1, K2, and K3 were identified by NMR, LC-MS, and HRMS. The kaempferol degradation pathway leading to the K1, K2, and K3 formation is proposed. It was observed that the more water concentration in the irradiation medium increases, the more K2 concentration increases. Comprehension of food preservation is not clear because many phenomena occurring during irradiation are not established. Radiolysis of kaempferol in water/methanol mixtures helps to elucidate the phenomenon and it is possible that during the treatment of nutriments by gamma-irradiation, a series of products such as depside K2 could be formed. Antioxidant properties of kaempferol radiolysis products were evaluated according to their capacity to decrease the EPR DPPH (1,1-diphenyl-2-picrylhydrazil) signal and to inhibit superoxide radicals formed by the enzyme reaction "xanthine + xanthine oxidase".
authors.affiliation: UPRES EA 1085, Biomolécules et Cibles Cellulaires Tumorales, Faculté de Pharmacie, 2 rue du Dr. Marcland, 87025 Limoges Cedex, France.
authors.forename: Abdelghafour
authors.initials: A
authors.lastname: Marfak
authors.forename: Patrick
authors.initials: P
authors.lastname: Trouillas
authors.forename: Daovy-Paulette
authors.initials: DP
authors.lastname: Allais
authors.forename: Yves
authors.initials: Y
authors.lastname: Champavier
authors.forename: Claude-Alain
authors.initials: CA
authors.lastname: Calliste
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Duroux
mesh_terms: D000975:Antioxidants / Q000494:pharmacology* / Q000528:radiation effects*; D002851:Chromatography, High Pressure Liquid; D003037:Cobalt Radioisotopes; D005419:Flavonoids / Q000494:pharmacology* / Q000528:radiation effects*; D005514:Food Irradiation; D005519:Food Preservation; D005609:Free Radicals / Q000737:chemistry; D005720:Gamma Rays; D044949:Kaempferols; D009682:Magnetic Resonance Spectroscopy; D000432:Methanol; D010084:Oxidation-Reduction; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D014867:Water
chemical_list: D000975:Antioxidants; D003037:Cobalt Radioisotopes; D005419:Flavonoids; D005609:Free Radicals; D044949:Kaempferols; D012996:Solutions; D014867:Water; C006552:kaempferol; D000432:Methanol