Characterization of highly polar bis-dihydrodiol epoxide—DNA adducts formed after metabolic activation of dibenz[a,h]anthracene

• Published in: Carcinogenesis (New York) 1993-05, Vol.14 (5), p.863-867
• Main Authors: Fuchs, Jürgen, Mlcoch, Jiri, Platt, Karl-Ludwig, Oesch, Franz
• Format: Article
• Language: English
• Subjects: Animals; Benz(a)Anthracenes - metabolism; Biological and medical sciences; Biotransformation; Carcinogenesis, carcinogens and anticarcinogens; Chemical agents; Chromatography, High Pressure Liquid; Deoxyribonucleosides - isolation & purification; DNA - chemistry; DNA - metabolism; Male; Medical sciences; Microsomes, Liver - metabolism; Molecular Structure; Rats; Rats, Sprague-Dawley; Spectrometry, Fluorescence; Tumors
• ISSN: 0143-3334; 1460-2180
• DOI: 10.1093/carcin/14.5.863

Dibenz(a,h)anthracene as well as a biologically important metabolite of dibenz[a,h]anthracene, namely the M-region dihydrodiol trans-3,4-dihydroxy-3,4-dihydrodibenz[a,h]anthracene were in addition to further metabolism to a bay region diol epoxide, extensively transformed to a distal bisdihydrodiol, 3,4,10,11-tetrahydroxy-3,4,10,11-tetrahydrodibenz[a,h]anthracene, which exhibited after renewed metabolic activation high DNA binding efficiency, leading to a new class of very polar DNA adducts. After incubation of dibenz[a,h]anthracene with DNA in the presence of liver microsomes from Aroclor 1254 treated male Sprague- Dawley rats highly polar DNA adducts probably originating from 3R,4R,10R,11R-tetrahydroxy-3,4,10,11-tetrahydrodibenz[a,h]anthracene and 3R,4R,10S,11S-tetrahydroxy-3,4,10,11-tetrahydrodibenz(a,h)anthracene were identified by reversed phase HPLC and by the 32P-postlabelling method. The adducts obtained were further characterized by comparing their fluorescence spectra with those obtained from 3,4,10,11-tetrahydroxy-3,4,10,11-tetrahydrodibenz[a,h]anthracene and from 3,4-dihydroxy-3,4-dihydrobenz[a]anthracene, the putative chromophore of the polar adduct. DNA adducts formed via 3S,4S,10S,11S-tetrahydroxy-3,4,10,11-tetrahydro-dibenz[a,h]anthracene were not found. After incubation of 14C-labelled dibenz(a,h)anthracene highly polar DNA adducts derived from the bisdihydrodiol contributed 38% to the adducts found in the HPLC profile. Bay region diol epoxide adducts represented a fraction of 25%. Using the32P-postlabelling technique a higher DNA binding yield for the racemic bisdihydrodiol (38 ± 12 pmol/mg DNA) was calculated than for the most active 3,4-dihydrodiol enantiomer, 3R,4R-dihydroxy-3,4-dihydrodibenz[a,h]anthracene (23 ± 6 pmol/mg DNA).