ACTIVITY OF 3-CARBETHOXYANGELICIN PHOTOLYSIS PRODUCTS

3-Carbethoxyangelicin (3-CA), carrying an electron-withdrawing group a t the pyrone side, has been prepared to have a fully monofunctional an gelicin derivative. 3-CA does not photoreact with DNA and induces a mo derate antiproliferative activity. 3-CA proved to be extremely sensiti ve to ultraviolet A (UVA) light, undergoing rapid photolysis. Only one photolysis product has been isolated and identified. By means of alka line elution, we observed that 3-CA and its photolysis products are ab le to induce a large amount of single-strand breaks in DNA in vivo. Th e results obtained from studying the capacity to produce singlet oxyge n suggest that the photodynamic mechanism of action of 3-CA very likel y results from its capacity-as well as that of its photolysis products -to produce singlet oxygen. (C) 1997 Elsevier Science S.A.