title: The photodegradation of quercetin: relation to oxidation.
abstract: The photostability of quercetin in alcoholic solutions was studied. Both UVA and UVB light induced degradation of quercetin, yielding a single product 1 deriving from oxidation and addition of an alcohol molecule to the 2,3 double bond. The same mechanism operated when quercetin was dissolved in alkaline solutions, and again a product 2 due to oxidation and addition of water was characterized. Comparison with quercetin analogs confirmed that, despite the presence of five hydroxy groups in quercetin, those in positions 3, 3', and 4' are mainly involved in the antioxidant activity of the compound , as well as in its photolability.
authors: Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy.
authors: Stefano
authors: S
authors: Dall'Acqua
authors: Giorgia
authors: G
authors: Miolo
authors: Gabbriella
authors: G
authors: Innocenti
authors: Sergio
authors: S
authors: Caffieri
mesh_terms: D000641:Ammonia / Q000737:chemistry; D047310:Apigenin / Q000737:chemistry / Q000528:radiation effects; D004355:Drug Stability; D000431:Ethanol / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry / Q000528:radiation effects; D006863:Hydrogen-Ion Concentration; D044949:Kaempferols / Q000737:chemistry / Q000528:radiation effects; D000432:Methanol / Q000737:chemistry; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D011794:Quercetin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000528:radiation effects; D012431:Rutin / Q000737:chemistry / Q000528:radiation effects; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
chemical_list: D005419:Flavonoids; D044949:Kaempferols; D012996:Solutions; D012997:Solvents; C037032:galangin; D000431:Ethanol; D012431:Rutin; C006552:kaempferol; D000641:Ammonia; D047310:Apigenin; D011794:Quercetin; D000432:Methanol