Schrader T J, Cherry W, Soper K, Langlois I
Toxicology Research Division, Bureau of Chemical Safety, Food Directorate, Health Canada, Ottawa, Ont., Canada K1A 0L2.
Mutat Res. 2006 Jul 14;606(1-2):61-71. doi: 10.1016/j.mrgentox.2006.02.008. Epub 2006 May 15.
Previously, Alternaria extract and metabolite mutagenicities+/-nitrosylation were characterized using Ames Salmonella strains TA98 and TA100, which are both reverted at GC sites. To examine other targets for mutation, the metabolites Altertoxin I (ATX I), Altenuene (ALT), Alternariol (AOH), Alternariol monomethyl ether (AME), Tentoxin (TENT), Tenuazonic acid (TA) and Radicinin (RAD) were reexamined+/-nitrosylation, using Ames Salmonella strain TA97, sensitive to frameshift mutations at a run of C's, as well as strains TA102 and TA104, reverted by base pair mutations at AT sites and more sensitive to oxidative damage. ATX I was also assessed for mammalian mutagenicity at the Hprt gene locus in Chinese hamster V79 lung fibroblasts and rat hepatoma H4IIE cells. When tested from 1 to 100 microg/plate without nitrosylation, ATX I was mutagenic in TA102+/-rat liver S9 for activation and weakly mutagenic in TA104+/-S9, demonstrating direct-acting AT base pair mutagenicity. AOH was also directly mutagenic at AT sites in TA102+/-S9 while AME was weakly mutagenic in TA102+/-S9 and TA104+S9. Nitrosylation of ATX I enhanced mutagenicity at AT sites in TA104+/-S9 but produced little change in TA102+/-S9 compared to native ATX I. However, nitrosylated ATX I generated a potent direct-acting frameshift mutagen at C sites in TA97+/-S9. While ATX I was not mutagenic in either V79 cells or H4IIE cells, 5 and 10 microg/ml nitrosylated ATX I produced a doubling of 6-thioguanine resistant V79 colonies and 0.5 and 1 microg/ml were mutagenic to H4IIE cells, becoming toxic at higher concentrations. These results suggest ATX I, AME and AOH induce mutations at AT sites, possibly through oxidative damage, with nitrosylation enhancing ATX I frameshift mutagenicity at runs of C's. Nitrosylated ATX I was also directly mutagenic in mammalian test systems.
此前，使用艾姆斯沙门氏菌菌株TA98和TA100对链格孢提取物和代谢产物的致突变性±亚硝化作用进行了表征，这两种菌株均在GC位点发生回复突变。为了研究其他突变靶点，使用对C碱基连续出现时的移码突变敏感的艾姆斯沙门氏菌菌株TA97，以及在AT位点通过碱基对突变回复且对氧化损伤更敏感的菌株TA102和TA104，重新检测了代谢产物Altertoxin I（ATX I）、Altenuene（ALT）、Alternariol（AOH）、Alternariol单甲醚（AME）、Tentoxin（TENT）、细交链孢菌酮酸（TA）和Radicinin（RAD）的±亚硝化作用。还在中国仓鼠V79肺成纤维细胞和大鼠肝癌H4IIE细胞的次黄嘌呤 - 鸟嘌呤磷酸核糖转移酶（Hprt）基因位点评估了ATX I的哺乳动物致突变性。当在不进行亚硝化的情况下以1至100微克/平板进行测试时，ATX I在TA102±大鼠肝脏S9存在下用于激活时具有致突变性，在TA104±S9存在下具有弱致突变性，表明其具有直接作用的AT碱基对致突变性。AOH在TA102±S9存在下也在AT位点具有直接致突变性，而AME在TA102±S9和TA104 + S9存在下具有弱致突变性。ATX I的亚硝化增强了TA104±S9中AT位点的致突变性，但与天然ATX I相比，在TA102±S9中变化不大。然而，亚硝化的ATX I在TA97±S9中产生了一种强效的直接作用的C位点移码诱变剂。虽然ATX I在V79细胞或H4IIE细胞中均无致突变性，但5和10微克/毫升的亚硝化ATX I使6 - 硫鸟嘌呤抗性V79菌落数量增加了一倍，0.5和1微克/毫升对H4IIE细胞具有致突变性，在更高浓度下具有毒性。这些结果表明，ATX I、AME和AOH可能通过氧化损伤在AT位点诱导突变，亚硝化增强了ATX I在C碱基连续出现时的移码致突变性。亚硝化的ATX I在哺乳动物测试系统中也具有直接致突变性。
