DNA adducts of the carcinogen, 15, 16-dihydro-11-methylcyclo-penta(a)phenanthren-17-one, in vivo and in vitro: high pressure liquid chromatographic separation and partial characterization

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Abstract
The 11-methyl derivative (11-methyl ketone) is the most carcinogenic of the series of methylated derivatives based on 15, 16-dihydro-cyclopenta[a]phenanthren-17-one. The nudeoside adducts derived from [3H]-11-methyl ketone-modified mouse skin DNA have been separated by both Sephadex LH-20 chromatography and reverse-phase h.p.l.c and compared to those derived from DNA modified in vitro with the [14C]-11-methyl ketone using rat liver microsomes. The in vivo modified DNA separated to give 6 adducts (designated I- VI) on h.p.l.c. The major in vivo adduct (80% total adducts) co-chromatographed with the major in vitro adduct. The metabolites of the 11-methyl ketone (designated a-g) have been separated by h.p.l.c, and the adducts derived from each of these individual metabolites determined by further metabolism in the presence of DNA. H.p.l.c. separation of these adducts has allowed characterization of the in vivo adducts. The major adduct (V) and possibly one of the minor adducts (IV) were derived from the 3, 4-dihydro-3, 4-diol of the 11-methyl ketone (metabolite e). Adducts II and III were derived from the 16- and 15-monohydroxylated derivatives of the 11-methyl ketone and also from their corresponding 3, 4-diols and therefore are likely to be the 16- and 15-hydroxy derivatives, respectively, of adduct V. Adduct VI, however, although derived from the 15-hydroxy-3, 4-diol had a late retention time on h.p.l.c, suggesting either a non-diol-epoxide adduct or a deoxyadenosine adduct. The use of [3H-G]DNA has established that the major adduct (V) and the 16-hydroxy-derived adduct (II) contain deox-yguanosine. Reaction of the carcinogen with [3H-A]poly(dA-dT) gave adduct VI which was the only adduct peak shown to contain [3H]deoxyadenosine.

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