5-Methoxypsoralen, an ingredient in several suntan preparations, has lethal, mutagenic and clastogenic properties
Many furocoumarins found in several species of plant1,2 are potent photosensitizing agents known to cause lethal and mutagenic effects in a wide range of organisms, from viruses to man2. Their role in the aetiology of cancer is debatable3-8, but work has focused on the PUVA (psoralen-UVA) treatment of psoriasis with 8-methoxypsoralen (8-MOP) and near UV radiation9-18. Bergaptene (5-methoxypsoralen, 5-MOP) is a major constituent of oil of bergamot1,19, and might be expected to have qualitatively similar photosensitizing properties to 8-MOP. Although 5-MOP is widely used as a stimulus to melanin deposition in several suntan preparations surprisingly little is known about its basic photobiology2. We report here that 5-MOP has the expected properties of other biologically active furocoumarins. These properties include lethal and mutagenic photosensitization of bacteria, `dark' induced frameshift mutagenesis in bacteria, and lethal and clastogenic effects on mammalian cells in tissue culture.