Induction of DNA-DNA Cross-Link Formation in Human Cells by Various Psoralen Derivatives1

Furocoumarin-induced DNA damage, monoadducts, and cross-links were measured in normal human, xeroderma pigmentosum, and Panconi's anemia cells after exposure to near-UV (356 nm). At similar concentrations and near-UV doses, photoad dition by 8-methoxypsoralen was twice that by angelicin and the substitution of bromodeoxyuridine for thymidine in one strand of DNA did not alter the binding. The rate of cross-linking by 8methoxypsoralen was twice that of 5-methoxypsoralen. Low frequencies of cross-links were detected from angelicin and 3carbethoxypsoralen but none were detected from 5-geranoxypsoralen at concentrations up to 25 /¿g/mland near-UV doses up to 45,000 J/m2.