von Däniken A, Lutz W K, Jäckh R, Schlatter C
Toxicol Appl Pharmacol. 1984 May;73(3):373-87. doi: 10.1016/0041-008x(84)90089-9.
It was the aim of this investigation to determine whether covalent binding of di(2-ethylhexyl) phthalate (DEHP) to rat liver DNA and of di(2-ethylhexyl) adipate (DEHA) to mouse liver DNA could be a mechanism of action contributing to the observed induction of liver tumors after lifetime feeding of the respective rodent species with high doses of DEHP and DEHA. For this purpose, DEHP and DEHA radiolabeled in different parts of the molecule were administered orally to female rats and mice, respectively, with or without pretreatment for 4 weeks with 1% unlabeled compound in the diet. Liver DNA was isolated after 16 hr and analyzed for radioactivity. The data were converted to a covalent binding index, CBI = (micromoles of substance bound per mole of DNA nucleotides)/(millimoles of substance applied per kilogram body weight), in order to allow a quantitative comparison also with other carcinogens and noncarcinogens. Administration of [14C]carboxylate-labeled DEHP to rats resulted in no measurable DNA radioactivity. The limit of detection, CBI less than 0.02 was about 100 times below the CBI of compounds where an observable tumor-inducing potential could be due to genotoxicity. With [14C]- and [3H]DEHP labeled in the alcohol moiety, radioactivity was clearly measurable in rat liver DNA. HPLC analysis of enzyme-degraded or acid-hydrolyzed DNA revealed that the natural nucleosides or purine bases were radiolabeled whereas no radioactivity was detectable in those fractions where the carcinogen-modified nucleoside or base adducts are expected. The respective limits of detection were at 0.07 and 0.04 CBI units for the 14C and 3H labels, respectively. The experiments with [14C]- and [3H]DEHA, labeled in the alcohol moiety and administered to mice, revealed a minute radioactivity of less than 50 dpm/mg liver DNA, too little to allow a nucleoside analysis to determine that fraction of the radioactivity which had been incorporated via biosynthesis. Expressed in the CBI units, values of 0.05 to 0.15 for 14C and 0.01 to 0.12 for 3H resulted. Determination of the level of 14CO2 expiration revealed a linear correlation with the specific activity of DNA. Experiments with 2-ethyl[1-14C]hexanol performed with both rats and mice allowed the conclusion that most if not all DEHA radioactivity in mouse liver DNA was due to biosynthetic incorporation. A maximum possible true DNA binding by DEHA must be below CBI 0.01.(ABSTRACT TRUNCATED AT 400 WORDS)
本研究的目的是确定邻苯二甲酸二（2-乙基己基）酯（DEHP）与大鼠肝脏DNA的共价结合以及己二酸二（2-乙基己基）酯（DEHA）与小鼠肝脏DNA的共价结合是否可能是一种作用机制，有助于解释在用高剂量DEHP和DEHA终身喂养相应啮齿动物后观察到的肝脏肿瘤诱导现象。为此，分别给雌性大鼠和小鼠口服分子不同部位放射性标记的DEHP和DEHA，饮食中添加或不添加1%未标记化合物进行4周预处理。16小时后分离肝脏DNA并分析放射性。数据转换为共价结合指数，CBI =（每摩尔DNA核苷酸结合的物质微摩尔数）/（每千克体重施用的物质毫摩尔数），以便也能与其他致癌物和非致癌物进行定量比较。给大鼠施用[14C]羧酸盐标记的DEHP后，未检测到可测量的DNA放射性。检测限，CBI小于0.02，比可能因基因毒性而具有明显肿瘤诱导潜力的化合物的CBI低约100倍。用醇部分标记的[14C] - 和[3H]DEHP进行实验时，大鼠肝脏DNA中可清楚检测到放射性。对酶降解或酸水解的DNA进行HPLC分析表明，天然核苷或嘌呤碱基被放射性标记，而在预期致癌物修饰的核苷或碱基加合物的那些部分中未检测到放射性。14C和3H标记的各自检测限分别为0.07和0.04 CBI单位。用醇部分标记并施用于小鼠的[14C] - 和[3H]DEHA实验表明，肝脏DNA的放射性小于50 dpm/mg，太少以至于无法通过核苷分析确定通过生物合成掺入的放射性部分。以CBI单位表示，14C的值为0.05至0.15，3H的值为0.01至0.12。14CO2呼出水平的测定显示与DNA的比活性呈线性相关。用2-乙基[1-14C]己醇对大鼠和小鼠进行的实验得出结论，小鼠肝脏DNA中大部分（如果不是全部）DEHA放射性是由于生物合成掺入。DEHA与DNA的最大可能真实结合必须低于CBI 0.01。（摘要截断于400字）
