Photodegradation of Folate Sensitized by Riboflavin
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
20/10/2012
20/10/2012
2011
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Resumo |
Folate is shown to react with singlet-excited state of riboflavin in a diffusion controlled reaction and with triplet-excited state of riboflavin in a somewhat slower reaction with (3)k(q) = 4.8 x 10(8) L mol(-1) s(-1) in aqueous phosphate buffer at pH 7.4, ionic strength of 0.2 mol L(-1), and 25 degrees C. Singlet quenching is assigned as photo-induced reductive electron transfer from ground state folate to singlet-excited riboflavin, while triplet quenching is assigned as one-electron transfer rather than hydrogen atom transfer from folate to triplet-excited riboflavin, as the reaction quantum yield, phi = 0.32, is hardly influenced by solvent change from water to deuterium oxide, phi = 0.37. Cyclic voltammetry showed an irreversible two-electron anodic process for folate, E = 1.14 V versus NHE at a scan-rate of 50 mV s(-1), which appears to be kinetically controlled by the heterogeneous electron transfer from the substrates to the electrode. Main products of folate photooxidation sensitized by riboflavin were pterin-6-carboxylic acid and p-aminobenzoyl-L-glutamic acid as shown by liquid chromatographic ion-trap mass spectrometry (LC-IT-MS). Fundacao de Amparo a Pesquisa do Estado de Sao Paulo-FAPESP[09/00858-0] Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) |
Identificador |
PHOTOCHEMISTRY AND PHOTOBIOLOGY, v.87, n.4, p.840-845, 2011 0031-8655 http://producao.usp.br/handle/BDPI/31837 10.1111/j.1751-1097.2011.00916.x |
Idioma(s) |
eng |
Publicador |
WILEY-BLACKWELL |
Relação |
Photochemistry and Photobiology |
Direitos |
restrictedAccess Copyright WILEY-BLACKWELL |
Palavras-Chave | #AQUEOUS-SOLUTION #FOLIC-ACID #5-METHYLTETRAHYDROFOLATE #OXIDATION #PHOTOLYSIS #KINETICS #MILK #Biochemistry & Molecular Biology #Biophysics |
Tipo |
article original article publishedVersion |