High-dose vitamin E lowers urine porphyrin levels in patients affected by porphyria cutanea tarda.
Porphyria cutanea tarda (PCT) is a metabolic disorder of heme biosynthesis, characterized by reduced uroporphyrinogen decarboxylase (UROD) activity and increased urinary excretion of eight and seven carboxyl group porphyrins. Specific factors such as iron, alcohol and halogenated compounds further inhibit enzyme activity by generating reactive oxygen species. Antioxidant vitamin E has frequently been used to counteract oxidative stress in porphyria patients, but a number of studies have failed to detect any significant effect on porphyrin metabolism. Since the use of vitamin E in the treatment of porphyria is a debated question, it seemed of interest to administer high doses to five patients with PCT in order to evaluate the effects on urine porphyrin excretion. The patients had high urinary porphyrin excretion levels, but vitamin E significantly reduced the urinary excretion of eight carboxyl group porphyrins. This result is attributable to the increase in UROD activity caused by the vitamin, which is a known scavenger of the oxygen reactive species that interfere with the activity of the enzyme. In conclusion, this paper shows that vitamin E high doses significantly lowers the urine porphyrin excretion in studied patients affected by PCT.
Pinelli
Arnaldo
A
Department of Pharmacology, Chemotherapy and Medical Toxicology, Milan, Italy. arnaldo.pinelli@unimi.it
Trivulzio
Silvio
S
Tomasoni
Livio
L
Bertolini
Boris
B
Pinelli
Giovanna
G
D016166:Free Radical Scavengers / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D017119:Porphyria Cutanea Tarda / Q000188:drug therapy / Q000652:urine*; D014575:Uroporphyrinogen Decarboxylase / Q000378:metabolism; D014578:Uroporphyrins / Q000652:urine*; D014810:Vitamin E / Q000008:administration & dosage / Q000627:therapeutic use*
D016166:Free Radical Scavengers; D014578:Uroporphyrins; D014810:Vitamin E; D014575:Uroporphyrinogen Decarboxylase