Inhibition of 5-aminolevulinic acid-induced DNA damage by melatonin, N1-acetyl-N2-formyl-5-methoxykynuramine, quercetin or resveratrol.

Porphyrias are defined as either inborn or acquired diseases related to enzymatic deficiencies in the heme biosynthetic pathway. Lead poisoning, hereditary tyrosinemia, and acute intermittent porphyria (AIP) are characterized by the absence of photosensitivity and the accumulation of 5-aminolevulinic acid (ALA) together with its increased urinary excretion. The main clinical manifestations of AIP are intermittent attacks of abdominal pain, neuromuscular weaknesses and neuropsychiatry alterations, and also an association with primary liver cancer, in which may be involved the oxidative potential of ALA which is able to cause DNA damage. The use of antioxidants in the treatment of ALA-induced oxidative stress is not well established. In the current work, we show the antioxidant efficacy of several compounds including melatonin, quercetin, resveratrol and N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), a melatonin oxidation product, in terms of their ability to limit DNA damage induced by ALA/Fe2+ in an in vitro system. Damage was measured by plasmid DNA strand breaks and detection of 8-oxo, 7-8-dihydro,2'-deoxyguanosine (8-oxodGuo) by high-performance liquid chromatography coupled with electrochemical detection. All compounds tested showed a dose-dependent protective action against free radical damage. These results could be the first step toward studies of the possible use of these antioxidants in oxidative stress promoted by ALA or other pro-oxidants.