Skálová Lenka, Nobilis Milan, Szotáková Barbora, Kondrová Eliska, Savlík Michal, Wsól Vladimír, Pichard-Garcia Lydiane, Maser Edmund
Department of Biochemical Sciences, Faculty of Pharmacy, Charles University, Research Centre LN00B12, Heyrovského 1203, CZ-500 05 Hradec Králové, Czech Republic.
Biochem Pharmacol. 2002 Jul 15;64(2):297-305. doi: 10.1016/s0006-2952(02)01068-7.
Benfluron (B, [5-(2-N-oxo-2-N',N"-dimethylaminoethoxy)-7-oxo-7H-benzo[c]fluorene]) is a potential benzo[c]fluorene antineoplastic agent with high activity against a broad spectrum of experimental tumors in vitro and in vivo. The structure of B has been modified to repress its rapid deactivation through carbonyl reduction on C7. 3,9-Dimethoxybenfluron (D, [3,9-dimethoxy-5-(2-N-oxo-2-N',N"-dimethylaminoethoxy)-7-oxo-7H-benzo[c]fluorene]) is one of the B derivatives developed. The present paper was designed to compare the C7 carbonyl reduction of B and D in microsomes, cytosol and hepatocytes from human liver. Two purified human enzymes, microsomal 11beta-hydroxysteroid dehydrogenase 1 (11beta-HSD 1) and cytosolic carbonyl reductase, were tested if they are responsible for B and D carbonyl reduction in the respective fractions. Indeed, carbonyl reduction of D in comparison to that of B was 4 and 6-10 times less extensive in human liver microsomes and cytosol, respectively. Moreover, about 10-20 times higher amounts of dihydro B than dihydro D were detected in primary culture of human hepatocytes. 11beta-HSD 1 was shown to be able to reduce B and D. For this enzyme, about 10 times higher rates of carbonyl reduction were observed for B than for D. Likewise, CR participates in B and D carbonyl reduction, although smaller amounts of both reduced metabolites were detected. In summary, carbonyl reduction of D was significantly less extensive than that of B in all in vitro experiments. This lower rate of D inactivation was especially pronounced in hepatocytes which represent a close to in vivo situation. Our results clearly demonstrate that dimethoxy substitution protects the carbonyl group of the benzo[c]fluorene moiety against the deactivation by microsomal and cytosolic reductases. Detailed knowledge on the participating enzymes may serve as a basis for the co-application of specific inhibitors in chemotherapy to further improve the pharmacokinetics of benzo[c]fluorene derivatives.
苯氟隆（B，[5-(2-N-氧代-2-N',N''-二甲基氨基乙氧基)-7-氧代-7H-苯并[c]芴]）是一种潜在的苯并[c]芴类抗肿瘤药物，在体外和体内对多种实验性肿瘤具有高活性。B的结构已被修饰，以抑制其通过C7羰基还原而迅速失活。3,9-二甲氧基苯氟隆（D，[3,9-二甲氧基-5-(2-N-氧代-2-N',N''-二甲基氨基乙氧基)-7-氧代-7H-苯并[c]芴]）是已开发的B衍生物之一。本文旨在比较人肝脏微粒体、细胞溶质和肝细胞中B和D的C7羰基还原情况。测试了两种纯化的人酶，微粒体11β-羟基类固醇脱氢酶1（11β-HSD 1）和细胞溶质羰基还原酶，看它们是否分别负责各部分中B和D的羰基还原。实际上，与B相比，人肝脏微粒体和细胞溶质中D的羰基还原程度分别低4倍和6至10倍。此外，在人肝细胞原代培养物中检测到的二氢B的量比二氢D高约10至20倍。已证明11β-HSD 1能够还原B和D。对于这种酶，观察到B的羰基还原速率比D高约10倍。同样，CR参与B和D的羰基还原，尽管检测到的两种还原代谢物的量较少。总之，在所有体外实验中，D的羰基还原程度明显低于B。在代表接近体内情况的肝细胞中，D的这种较低失活速率尤为明显。我们的结果清楚地表明，二甲氧基取代保护苯并[c]芴部分的羰基不被微粒体和细胞溶质还原酶失活。关于参与的酶的详细知识可作为在化疗中共同应用特定抑制剂的基础，以进一步改善苯并[c]芴衍生物的药代动力学。
