Enzyme antioxidant defences and oxidative damage in red blood cells of variegate porphyria patients

Abstract

Variegate porphyria is the result of decreased protoporphyrinogen oxidase (PPOX) activity, the penultimate enzyme of haem biosynthesis. Haem precursors can produce free radicals and activate oxygen-inducing oxidative stress. Our aim was to analyse the effects of variegate porphyria on haemoglobin levels, antioxidant enzyme activities and oxidative damage in circulating erythrocytes. Twelve women affected by variegate porphyria and 12 control healthy women participated in the study. Women affected by variegate porphyria presented reduced PPOX content and δ-aminolevulinic acid dehydratase activity in erythrocytes. Haemoglobin content and mean corpuscular volume were higher in the porphyric group. Erythrocyte glutathione reductase and superoxide dismutase activities and catalase content were higher in porphyric women, although MDA levels were also higher in the erythrocytes of the porphyric group. In conclusion, the determination of PPOX could be a useful method to detect variegate porphyria. Despite having higher antioxidant defences, erythrocytes of porphyric women have greater oxidative damage and higher corpuscular volume, which are both indices of a situation of higher oxidative stress. © W. S. Maney and Son Ltd 2009.