The protective role of dietary antioxidants (β-carotene) against free radical formation in anaerobes with continued exposure to oxygen

The linear furanocoumarins (or psoralens) are naturally occurring plant biosynthetic metabolites that have been used since ancient times in skin photochemotherapy. However, medicinal use of the psoralens has been linked with increased incidence of skin cancer in humans. To understand some of the mechanism of this toxicity, we tested increasing concentrations of the psoralens bergapten (5-methoxypsoralen) and xanthotoxin (8-methoxypsoralen) for toxicity against Wistar rats. As dietary concentrations of each compound increased, weight gain in both male and female rats decreased. Feeding on diet containing these chemicals also decreased rat birth rate, but did not significantly affect individual litter weight or date of birth. Xanthotoxin appeared to be more toxic than bergapten.