Martin E A, Heydon R T, Brown K, Brown J E, Lim C K, White I N, Smith L L
MRC Toxicology Unit, Leicester, UK.
Carcinogenesis. 1998 Jun;19(6):1061-9. doi: 10.1093/carcin/19.6.1061.
A novel HPLC system has been developed that has allowed the separation of tamoxifen DNA adducts formed in the livers of rats and mice treated with this drug. At least 13 different peaks have been separated from 32P-post-labelled DNA, with two major peaks jointly accounting for >60% of the total adducts formed by tamoxifen in the livers of treated rats and mice. This is a great improvement on the resolution obtained by thin layer chromatography, which separates the adducts into one main product consisting of a group of major adduct spots eluting together, plus several other minor spots. Identification of the nature of some of the peaks has been investigated. Comparisons of the products formed when alpha-acetoxytamoxifen is reacted with DNA in vitro with 32P-post-labelled liver DNA adducts from rats treated with tamoxifen or alpha-hydroxytamoxifen in vivo, appear to confirm that a major route of activation of tamoxifen in vivo is via alpha-hydroxylation. The resolving power of this HPLC system has further extended this result to show that six of the peaks, including the two major peaks, are formed by the reaction of an activated alpha-hydroxytamoxifen with DNA. Activation of 4-hydroxytamoxifen by the peroxidase/H2O2 system in vitro gives a more polar DNA adduct seen only at trace levels in liver DNA from tamoxifen-treated rats and mice.
已开发出一种新型高效液相色谱（HPLC）系统，该系统能够分离在用该药物处理的大鼠和小鼠肝脏中形成的他莫昔芬DNA加合物。从32P后标记的DNA中已分离出至少13个不同的峰，其中两个主要峰合起来占处理过的大鼠和小鼠肝脏中他莫昔芬形成的总加合物的60%以上。这比薄层色谱法所获得的分辨率有了很大提高，薄层色谱法将加合物分离成一个主要产物，该产物由一组一起洗脱的主要加合物斑点组成，再加上其他几个次要斑点。已对其中一些峰的性质进行了鉴定研究。将α-乙酰氧基他莫昔芬与DNA在体外反应形成的产物，与用他莫昔芬或α-羟基他莫昔芬在体内处理的大鼠的32P后标记肝脏DNA加合物进行比较，似乎证实了他莫昔芬在体内的主要活化途径是通过α-羟基化。该HPLC系统的分辨能力进一步扩展了这一结果，表明包括两个主要峰在内的六个峰是由活化的α-羟基他莫昔芬与DNA反应形成的。4-羟基他莫昔芬在体外经过氧化物酶/H2O2系统活化后，会产生一种极性更大的DNA加合物，这种加合物在他莫昔芬处理的大鼠和小鼠的肝脏DNA中仅以痕量水平出现。
