Free radical production during photo-assisted NADPH reduction of four alpha-nitroarenofurans.

Generation of radical anions during NADPH reduction of four mutagenic and genotoxic alpha-nitroarenofurans was examined. ESR showed that free radicals were generated during reduction solely in the presence of light. Computer simulations of ESR spectra were in good agreement with the experimental ones.

Microsomal metabolism of dibenz[a,c]anthracene, dibenz[a,h]anthracene and dibenz[a,j]anthracene to bis-dihydrodiols and polyhydroxylated products.

Polar, ethyl acetate soluble metabolites formed in incubations of dibenz[a,c]anthracene (DB[a,c]A), dibenz[a,h]anthracene (DB[a,h]A) and the related DB[a,h]A 3,4-diol and dibenz[a,j]anthracene (DB[a,j]A) with 3-methylcholanthrene (3-MC)-induced rat liver microsomal preparations have been separated by HPLC and examined using fluorescence, UV and NMR spectroscopy. Metabolites with spectral properties consistant with their identification as the 3,4:8,9-bis-diol of DB[a,j]A and a 1,2,3,4,12,13-hexol derived from DB[a,c]A were found. DB[a,h]A was metabolized to three polar products identified as the 3,4:10,11-bis-diol and the related 1,2,3,4,8,9- and 1,2,3,4,10,11-hexols, which were also formed, together with the related 1,2,3,4-tetrol, from the DB[a,h]A 3,4-diol.

Formation of cyclobutane thymine dimers photosensitized by pyridopsoralens: a triplet-triplet energy transfer mechanism.

The 365 nm irradiation of thymine thin films in the presence of pyridopsoralens is shown to induce the formation of cyclobutane thymine dimers, in contrast to other compounds such as 8- and 5-methoxypsoralen. In order to elucidate the mechanism of such a photosensitized reaction, we have determined the energy of the lowest triplet state (T1) of these compounds, using phosphorescence spectroscopy and CNDO/S quantum chemistry calculations. The T1 energy values were found to be significantly higher for pyridopsoralens--up to 0.

Reactivity with DNA of three pyrenofuran analogues of benzo(a)pyrene and benzo(e)pyrene.

Three pyrenofurans, the pyreno[1,2-b]furan (FP1), the pyreno[2,1-b] furan (FP2) and the pyreno[4,5-b]furan (FP3) have been synthesized as analogues of the mutagenic and carcinogenic benzo(a)pyrene (FP1 and FP2) and of its non-carcinogenic isomer benzo(e)pyrene (FP3). For each of the pyrenofurans, the reactivity with DNA has been tested in presence of liver microsomes of rats induced with 3-methylcholanthrene. Fluorescence spectroscopy showed that only FP2 and FP3 which possess a "bay region" react with DNA.