Singlet Oxygen Formation by Sensitization of Furocoumarins Complexed With, or Bound Covalently to Dna

— The formation of singlet molecular oxygen (1O2) by sensitization of the furocoumarins 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP) and psoralen complexed with DNA was investigated. From the results it is concluded that 5-MOP complexed with native DNA is able to generate 1O2, even in a larger extent than 5-MOP free in solution. Also, with 8-MOP and especially with psoralen, 1O2 formation by the complexed compound could be observed. The 1O2 formation sensitized by covalently bound furocoumarin was demonstrated with psoralen as a model compound. 4′,5′-Dihydropsoralen, a model compound for the UVA light absorbing 4′,5’monoadducts of furocoumarins to DNA, is also able to generate 1O2.