Effects of iron-loading and ethanol treatment on rat porphyrin metabolism

A safety study of a novel photosensitizer, sinoporphyrin sodium, for photodynamic therapy in Beagle dogs

Sinoporphyrin sodium (DVDMS) based photodynamic therapy (PDT) showed skin phototoxicity in Beagle dogs, did not accumulate in blood plasma, and had an effect on the immune organs and the liver.

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.

The role of possible membrane damage in porphyria cutanea tarda: a spin label study of rat liver cell membranes

Two groups of rats were made porphyric by treatment for a shorter or a longer time with hexachlorobenzene (HCB); a third group was subjected to chronic treatment with ethanol; the fourth group comprised untreated, control animals. Suspensions were prepared of hepatocytes isolated from the livers of the animals in the individual groups, and in these systems the cell membranes were studied by spin labeling. In all three chronically treated groups, the order parameter calculated from the ESR spectra was significantly lower than that of the control group. The order parameters ofr the first three treated groups, however, did not differ significantly from one another. If either HCB or ethanol was incorporated into the isolated hepatocytes of the healthy control animals, the fluidity of the hepatocyte membranes increased. The order parameter decrease (compared to the control) for the hepatocyte membranes of the animals treated chronically with HCB or ethanol can be ascribed to the direct membrane-fluidizing effect of HCB or ethanol, and also to the altered lipid metabolism. With regard to the difference in the mechanisms of action of HCB and ethanol, on the basis of the experimentally proved membrane-damaging effect of the porphyrinogenic HCB it is probable that, besides other factors, the membrane damage may play an important role in the pathogenesis of porphyria cutanea tarda.