Synthesis of trisubstituted psoralens as potential photosensitizing agents

Eight new trisubstituted psoralenes have been synthesized starting with 7-hydroxycoumarins. The photosensitizing activity of 8-aroyl-4,5-dimethylpsoralenes and 8-aroyl-4-methyl-4'-substituted psoralenes were compared to that of the very active xanthotoxin. Some representatives of the prepared psoralenes showed in vitro lethal photosensitizing activity on Bacillus subtilis