The syn- and anti-isomers of l,2-dihydroxy-3,4-epoxy-l,2,3,4-tetrahydro-6-methykhrysene (6-MeC-l,2-diol-3,4-epoxide) were synthesized and their mutagenk activities in Salmonella typhimurium were compared with those of the syn- and anti-isomers of l,2-dihydroxy-3,4-epoxy-l,2,3,4-tetrahydro-5-methykhrysene (5-MeC-l,2-diol-3,4-epoxide). The most mu-tagenic compound was anti-5-MeC-l,2-diol-3,4-epoxide, followed by syn-5-MeC-l,2-diol-3,4-epoxide. At the same doses, neither of the 6-MeC-l, 2-dioI-3, 4-poxides was mutagenic. These results demonstrate the enhancing effect on mutagenicity of a methyl group in the same bay region as the epoxide ring of a diol epoxide.
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The mass spectrometric measurements made by the Rockefeller University Mass Spectrometric Biotechnology Resource were supported by the Division of Research Resources, NIH. We appreciate the help of Dr AJadar Bencsath of Rockefeller University in obtaining mass spectral data, and Mr William Biles of the Naylor Dana Institute In Vitro Facility for performing the mutagcnicity assays. This study was supported by NCI Grants CA-32242 and CA-36097 and American Cancer Society Grant BC-132. A Study of Chemical Carcinogenesis, 99.