Hydroxyl radical generation and DNA strand scission mediated by natural anticancer and synthetic quinones

Using ESR and spin-trapping techniques, it was found that synthetic 2-dimethylamino-3-chloro-1,4-naphthoquinone and the natural anticancer quinone daunomycin, when added to a system containing purified NADPH-cytochrome P-450 reductase, NADPH, ferric ions, and oxygen, (i) generated hydroxyl radicals and (ii) caused single-strand scission of supercoiled DNA of the plasmic pBR322. Since these two effects of the quinones were correlated to each other, we propose that potential anticancer quinones can be effectively screened by measuring their ability to form hydroxyl radicals in the above system.