4,6,4'-TRIMETHYLANGELICIN INDUCES INTERSTRAND CROSS-LINKS IN MAMMALIAN-CELL DNA

4,6,4'-Trimethylangelicin, a well-known effective photosensitizer desc ribed as a pure monofunctional reactant with DNA, can induce interstra nd cross-links in mammalian cell DNA in vivo (about 15% relative to 8- methoxypsoralen), as observed using alkaline elution and Chinese hamst er ovary cells. Experiments performed using the two-step irradiation m ethod and HeLa cells support these data. In contrast with 4,6,4'-trime thylangelicin, 4'-methylangelicin and 4,4'-dimethylangelicin do not fo rm interstrand cross-links. These results are consistent with those re cently reported by Chen et al. (X. Chen, J. Kagan, F. Dall'Acqua, D. A verbeck and E. Bisagni, J. Photochem. Photobiol. B: Biol, 22 (1994) 51 -57) using pBR322 and M13 DNA. The cross-linking ability of 4,6,4'-tri methylangelicin does not seem to be related to a particular feature of these DNAs but to the compound itself.