El-Bayoumy K, Lavoie E J, Hecht S S, Fow E A, Hoffmann D
Mutat Res. 1981 Apr;81(2):143-53. doi: 10.1016/0027-5107(81)90029-4.
A series of nitrobiphenyls, nitronaphthalenes, and their methyl-substituted derivatives were assayed for mutagenicity toward S. typhimurium TA98 and TA100. In assays conducted in the absence of rat liver S9 fraction, substitution of a methyl group ortho to the nitro group decreased mutagenicity (3-methyl-4-nitrobiphenyl, 2-methyl-1-nitronaphthalene, and 3-methyl-2-nitronaphthalene). The mutagenicity of 4-nitrobiphenyl was also inhibited by methyl substitution at the 2'-position (2'-methyl-4-nitrobiphenyl), and at both the 3- and 2'-positions (3,2'-dimethyl-4-nitrobiphenyl). In assays conducted in the presence of rat liver S9 fraction, inhibition of mutagenicity by methyl substitution was demonstrated for 2-methyl-1-nitronaphthalene, 3-methyl-2-nitronaphthalene and 3,2'-dimethyl-4-nitrobiphenyl. Thus, methyl substitution of nitrobiphenyls and nitronaphthalenes generally decreased mutagenicity, when assays were conducted in the absence of rat liver S9 fraction. However, in the presence of rat liver S9 fraction, the inhibitory effect of methyl substitution on mutagenicity was less pronounced. These results contrast to the usual enhancing effect of ortho-methyl substitution of the corresponding aromatic amines and their N-oxidized derivatives (hydroxylamines and C-nitroso compounds).
对一系列硝基联苯、硝基萘及其甲基取代衍生物进行了针对鼠伤寒沙门氏菌TA98和TA100的致突变性测定。在无大鼠肝脏S9组分的测定中，硝基邻位的甲基取代降低了致突变性（3-甲基-4-硝基联苯、2-甲基-1-硝基萘和3-甲基-2-硝基萘）。4-硝基联苯的致突变性在2'-位（2'-甲基-4-硝基联苯）以及3-和2'-位（3,2'-二甲基-4-硝基联苯）进行甲基取代时也受到抑制。在有大鼠肝脏S9组分的测定中，2-甲基-1-硝基萘、3-甲基-2-硝基萘和3,2'-二甲基-4-硝基联苯的甲基取代均表现出对致突变性的抑制作用。因此，在无大鼠肝脏S9组分进行测定时，硝基联苯和硝基萘的甲基取代通常会降低致突变性。然而，在有大鼠肝脏S9组分时，甲基取代对致突变性的抑制作用则不那么明显。这些结果与相应芳香胺及其N-氧化衍生物（羟胺和C-亚硝基化合物）的邻位甲基取代通常具有的增强作用形成对比。
