DNA adduct formation from quaternary benzo[c]phenanthridine alkaloids sanguinarine and chelerythrine as revealed by the 32P-postlabeling technique |
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Authors: | Stiborová Marie Simánek Vilím Frei Eva Hobza Pavel Ulrichová Jitka |
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Affiliation: | Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 2 Prague, Czech Republic. stiborov@natur.cuni.cz |
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Abstract: | Using the 32P-postlabeling assay, we investigated the ability of quaternary benzo[c]phenanthridine alkaloids, sanguinarine, chelerythrine and fagaronine, to form DNA adducts in vitro. Two enhanced versions of the assay (enrichment by nuclease P1 and 1-butanol extraction) were utilized in the study. Hepatic microsomes of rats pre-treated with beta-naphthoflavone or those of uninduced rats, used as metabolic activators, were incubated in the presence of calf thymus DNA and the alkaloids, with NADPH used as a cofactor. Under these conditions sanguinarine and chelerythrine, but not fagaronine, formed DNA adducts detectable by 32P-postlabeling. DNA adduct formation by both alkaloids was found to be concentration dependent. When analyzing different atomic and bond indices of the C11-C12 bond (ring B) in alkaloid molecules we found that fagaronine behaved differently from sanguinarine and chelerythrine. While sanguinarine and chelerythrine showed a preference for electrophilic attack indicating higher potential to be activated by cytochrome P450, fagaronine exhibited a tendency for nucleophilic attack. Our results demonstrate that sanguinarine and chelerythrine are metabolized by hepatic microsomes to species, which generate DNA adducts. |
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