Weyand E H, Cai Z W, Wu Y, Rice J E, He Z M, LaVoie E J
College of Pharmacy, Rutgers, State University of New Jersey, Piscataway 08855-0789.
Chem Res Toxicol. 1993 Jul-Aug;6(4):568-77. doi: 10.1021/tx00034a028.
The primary mechanism of activation of benzo[b]fluoranthene (B[b]F) to a genotoxic agent does not involve the bay region dihydrodiol epoxide trans-9,10-dihydroxy-anti- 11,12-epoxy-9,10,11,12-tetrahydrobenzo[b]fluoranthene (B[b]F-9,10-DE). Previous results have suggested that the major DNA adduct(s) formed in vivo with B[b]F are more polar than those formed from B[b]F-9,10-DE. Employing newly-developed synthetic methods for the formation of B[b]F derivatives, trans-9,10-dihydro-5,9,10-trihydroxybenzo[b]fluoranthene (5-OH-B[b]F-9,10-diol) and trans-9,10-dihydro-6,9,10-trihydroxybenzo[b]fluoranthene (6-OH-B[b]F-9,10-diol) were synthesized and evaluated for tumor-initiating activity at initiation doses of 0.04, 0.12, and 0.4 mumol per mouse. In contrast to previous bioassay results, both of these phenolic dihydrodiols exhibited tumor-initiating activity. 5-OH-B[b]F-9,10-diol was the more potent tumor initiator, inducing a 90% incidence of tumor-bearing mice with an average of 7.50 tumors per mouse at a total initiator dose of 0.4 mumol. 6-OH-B[b]F-9,10-diol was significantly less active as a tumor initiator in this bioassay, inducing a 50% incidence of tumor-bearing mice with an average of 0.60 tumor per mouse at a total dose of 0.4 mumol. 32P-Postlabeling analysis was employed to evaluate the DNA adducts formed in vivo in mouse skin from both 5- and 6-OH-B[b]F-9,10-diol. HPLC analysis of B[b]F-DNA adducts formed in mouse skin demonstrated the presence of a single major adduct together with four additional minor adducts. The DNA adducts formed with 5-OH-B[b]F-9,10-diol had identical HPLC retention to the major and one of the minor adducts observed for B[b]F. These two DNA adducts account for 58% of the modified nucleotides detected in mouse skin following the topical application of B[b]F. Methods for the preparation of trans-9,10-dihydroxy-anti-11,12-epoxy-5-hydroxy-9,10,11,12- tetrahydrobenzo[b]fluoranthene (5-OH-B[b]F-9,10-DE) were developed. The DNA adducts formed with 5-OH-B[b]F-9,10-DE were similar to the adducts formed with 5-OH-B[b]F-9,10-diol. The results of the DNA binding studies along with the tumor-initiating data indicate that 5-OH-B[b]F-9,10-diol is the major proximate tumorigenic metabolite of B[b]F on mouse skin. Studies performed with deoxyguanosine 3'-phosphate suggest that the principal adducts formed with anti-5-OH-B[b]F-9,10-DE are the result of the interaction with deoxyguanosine.
苯并[b]荧蒽（B[b]F）激活成为遗传毒性剂的主要机制并不涉及湾区二氢二醇环氧化物反式-9,10-二羟基-反式-11,12-环氧-9,10,11,12-四氢苯并[b]荧蒽（B[b]F-9,10-DE）。先前的结果表明，B[b]F在体内形成的主要DNA加合物比由B[b]F-9,10-DE形成的加合物极性更强。利用新开发的合成方法来形成B[b]F衍生物，合成了反式-9,10-二氢-5,9,10-三羟基苯并[b]荧蒽（5-OH-B[b]F-9,10-二醇）和反式-9,10-二氢-6,9,10-三羟基苯并[b]荧蒽（6-OH-B[b]F-9,10-二醇），并以每只小鼠0.04、0.12和0.4 μmol的起始剂量评估其肿瘤起始活性。与先前的生物测定结果相反，这两种酚类二氢二醇均表现出肿瘤起始活性。5-OH-B[b]F-9,10-二醇是更强效的肿瘤起始剂，在总起始剂量为0.4 μmol时，诱导90%的荷瘤小鼠发生率，平均每只小鼠有7.50个肿瘤。在该生物测定中，6-OH-B[b]F-9,10-二醇作为肿瘤起始剂的活性明显较低，在总剂量为0.4 μmol时，诱导50%的荷瘤小鼠发生率，平均每只小鼠有0.60个肿瘤。采用32P后标记分析法评估5-OH-B[b]F-9,10-二醇和6-OH-B[b]F-9,10-二醇在小鼠皮肤中体内形成的DNA加合物。对小鼠皮肤中形成的B[b]F-DNA加合物进行HPLC分析，结果显示存在一种主要加合物以及另外四种次要加合物。5-OH-B[b]F-9,10-二醇形成的DNA加合物与B[b]F观察到的主要加合物和一种次要加合物具有相同的HPLC保留时间。这两种DNA加合物占局部应用B[b]F后在小鼠皮肤中检测到的修饰核苷酸的58%。开发了制备反式-9,10-二羟基-反式-11,12-环氧-5-羟基-9,10,11,12-四氢苯并[b]荧蒽（5-OH-B[b]F-9,10-DE）的方法。5-OH-B[b]F-9,10-DE形成的DNA加合物与5-OH-B[b]F-9,10-二醇形成的加合物相似。DNA结合研究结果以及肿瘤起始数据表明
