PMID- 20922252
OWN - NLM
STAT- MEDLINE
DCOM- 20110321
LR  - 20151119
IS  - 1474-9092 (Electronic)
IS  - 1474-905X (Linking)
VI  - 9
IP  - 12
DP  - 2010 Dec
TI  - Mechanism of photooxidation of folic acid sensitized by unconjugated pterins.
PG  - 1604-12
LID - 10.1039/c0pp00210k [doi]
AB  - Folic acid, or pteroyl-l-glutamic acid (PteGlu), is a precursor of coenzymes 
      involved in the metabolism of nucleotides and amino acids. PteGlu is composed of 
      three moieties: a 6-methylpterin (Mep) residue, a p-aminobenzoic acid (PABA) 
      residue, and a glutamic acid (Glu) residue. Accumulated evidence indicates that 
      photolysis of PteGlu leads to increased risk of several pathologies. Thus, a 
      study of PteGlu photodegradation can have significant ramifications. When an 
      air-equilibrated aqueous solution of PteGlu is exposed to UV-A radiation, the 
      rate of the degradation increases with irradiation time. The mechanism involved 
      in this "auto-photo-catalytic" effect was investigated in aqueous solutions using 
      a variety of tools. Whereas PteGlu is photostable under anaerobic conditions, it 
      is converted into 6-formylpterin (Fop) and p-aminobenzoyl-l-glutamic acid 
      (PABA-Glu) in the presence of oxygen. As the reaction proceeds and enough Fop 
      accumulates in the solution, a photosensitized electron-transfer process starts, 
      where Fop photoinduces the oxidation of PteGlu to Fop, and H(2)O(2) is formed. 
      This process also takes place with other pterins as photosensitizers. The results 
      are discussed with the context of previous mechanisms for processes 
      photosensitized by pterins, and their biological implications are evaluated.
FAU - Dantola, M Laura
AU  - Dantola ML
AD  - INIFTA, Departamento de Quimica, Facultad de Ciencias Exactas, Universidad 
      Nacional de La Plata, CCT La Plata-CONICET. C.C. 16, Suc. 4, (1900), La Plata, 
      Argentina.
FAU - Denofrio, M Paula
AU  - Denofrio MP
FAU - Zurbano, Beatriz
AU  - Zurbano B
FAU - Gimenez, Carlos S
AU  - Gimenez CS
FAU - Ogilby, Peter R
AU  - Ogilby PR
FAU - Lorente, Carolina
AU  - Lorente C
FAU - Thomas, Andres H
AU  - Thomas AH
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20101005
PL  - England
TA  - Photochem Photobiol Sci
JT  - Photochemical & photobiological sciences : Official journal of the European 
      Photochemistry Association and the European Society for Photobiology
JID - 101124451
RN  - 0 (Glutamates)
RN  - 0 (Photosensitizing Agents)
RN  - 0 (Pterins)
RN  - 17778-80-2 (Singlet Oxygen)
RN  - 712-30-1 (2-amino-4-hydroxy-6-formylpteridine)
RN  - 935E97BOY8 (Folic Acid)
RN  - 9BKY99A8HJ (4-aminobenzoylglutamic acid)
RN  - BBX060AN9V (Hydrogen Peroxide)
RN  - TL2TJE8QTX (4-Aminobenzoic Acid)
SB  - IM
MH  - 4-Aminobenzoic Acid/chemistry
MH  - Folic Acid/chemistry/*metabolism/radiation effects
MH  - Glutamates/chemistry/metabolism
MH  - Hydrogen Peroxide/chemistry
MH  - Oxidation-Reduction
MH  - *Photolysis
MH  - Photosensitizing Agents/*chemistry/metabolism/radiation effects
MH  - Pterins/*chemistry/metabolism/radiation effects
MH  - Singlet Oxygen/chemistry
MH  - Time Factors
MH  - Ultraviolet Rays
EDAT- 2010/10/06 06:00
MHDA- 2011/03/22 06:00
CRDT- 2010/10/06 06:00
PHST- 2010/10/06 06:00 [entrez]
PHST- 2010/10/06 06:00 [pubmed]
PHST- 2011/03/22 06:00 [medline]
AID - 10.1039/c0pp00210k [doi]
PST - ppublish
SO  - Photochem Photobiol Sci. 2010 Dec;9(12):1604-12. doi: 10.1039/c0pp00210k. Epub 
      2010 Oct 5.