IN-VITRO DNA CROSS-LINKING BY LEDAKRIN, AN ANTITUMOR DERIVATIVE OF 1-NITRO-9-AMINOACRIDINE

Using agarose gel electrophoresis we confirmed that Ledakrin is capabl e of incurring covalent crosslinking in pBR322 plasmid DNA and also in poly(dGdC) in the presence of a simple activating system containing D TT. The identification of adducts resulting from DNA crosslinking was carried out by P-32-post-labelling assay. We assumed that such adduct( s) should be brought about more readily with double-stranded than with single-stranded polynucleotides or nucleotides. Since our earlier exp eriments had shown that guanine is a major site of covalent binding of 1-nitroacridines, we compared DNA adduct formation by Ledakrin for ct DNA, dG-containing synthetic homopolymers and 3'-pdG. P-32-Post-labell ing assay revealed two adduct spots that were enhanced in samples cont aining double-stranded substrates in which interstrand crosslinking be tween guanines was possible, namely ctDNA and poly(dGdC). (C) 1997 Els evier Science Ireland Ltd.