Lipophilic antioxidants in patients with phenylketonuria.
BACKGROUND
Low serum ubiquinone-10 concentrations have been described in phenylketonuric patients fed natural-protein-restricted diets. Such low concentrations may be related to increased free radical damage.


OBJECTIVE
We evaluated the relation between low serum ubiquinone-10 concentrations and other lipophilic antioxidants (tocopherol and retinol), selenium, glutathione peroxidase activity, and malondialdehyde concentrations as a marker of lipid peroxidation.


METHODS
This was a cross-sectional study of 58 patients with phenylketonuria (aged 2-36 y; median: 13 y) under dietary treatment, 58 age-matched control subjects, and 30 children with moderate hyperphenylalaninemia fed unrestricted diets (aged 3-17 y; median: 7.5 y). Serum ubiquinone-10 concentrations were analyzed by HPLC with electrochemical detection. Serum retinol, serum tocopherol, and plasma malondialdehyde were analyzed by HPLC with ultraviolet detection.


RESULTS
A significant positive correlation was observed between ubiquinone-10 and tocopherol (r = 0.510, P < 0.001) in the patients with phenylketonuria. After the patients were stratified into 2 groups according to ubiquinone-10 values, significantly lower concentrations of tocopherol were observed in group 1 (low ubiquinone values) than in group 2 (normal ubiquinone values), the hyperphenylalaninemic children, and the control group. Plasma malondialdehyde concentrations were significantly higher in group 1 than in the other groups. No significant differences between groups 1 and 2 were observed in daily intakes of selenium, ascorbate, tocopherol, or retinol.


CONCLUSIONS
Plasma lipid peroxidation seems to be increased in phenylketonuria. Low concentrations of ubiquinone-10 could be associated with either excessive tocopherol consumption or high malondialdehyde concentrations in patients with phenylketonuria.
Colomé
Catrina
C
Serveis de Bioquímica, Hospital Sant Joan de Déu, Universitat de Barcelona, Spain.
Artuch
Rafael
R
Vilaseca
Maria-Antònia
MA
Sierra
Cristina
C
Brandi
Núria
N
Lambruschini
Nilo
N
Cambra
Francisco J
FJ
Campistol
Jaume
J
D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000378:metabolism*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015227:Lipid Peroxidation; D008297:Male; D018384:Oxidative Stress; D010661:Phenylketonurias / Q000097:blood* / Q000178:diet therapy; D024505:Tocopherols / Q000097:blood; D014451:Ubiquinone / Q000097:blood*
D000975:Antioxidants; D014451:Ubiquinone; C025204:Ubiquinone Q2; D024505:Tocopherols