PYRENYLBORONIC ACIDS AS A NOVEL ENTRY FOR PHOTOCHEMICAL DNA CLEAVAGE - DIRADICAL-FORMING PYRENE-1,6-DIYLDIBORONIC ACID MIMICS THE CLEAVAGE MECHANISM OF ENEDIYNE ANTITUMOR ANTIBIOTICS

Pyren-1-ylboronic acid 4 and pyrene-1,6-diyldiboronic acid 5 are bound to supercoiled double-strand circular DNA plasmid ColE1 (colDNA) and effect its efficient photocleavage under visible light irradiation. Me chanistic studies show that the cleavage occurs according to the radic al mechanism. The cleavage activity of monoacid 4 could be suppressed by the addition of D-fructose because of boronic acid-saccharide compl exation. Diacid 5 is bound to colDNA more strongly than is monoacid 4 and effects its efficient photocleavage to yield Form m. The results s how that diradical-forming diacid 5 is able to cleave DNA at two react ion sites, mimicking the cleavage mechanism of enediyne antitumor anti biotics.