7-N,7′-N′-(1″,2″-Dithianyl-3″,6″-dimethylenyl)bismitomycin C: synthesis and nucleophilic activation of a dimeric mitomycin
作者:Sang Hyup Lee、Harold Kohn
DOI:10.1039/b414806a
日期:——
Dimeric alkylating agents that modify complementary DNA strands have engendered significant interest. We have prepared the novel dimeric mitomycin, 7-N,7â²-Nâ²-(1â³,2â³-dithianyl-3â³,6â³-dimethylenyl)bismitomycin C (9), in which the mitomycins are bridged by a dithiane unit. Dimer 9, like the clinically tested acyclic disulfides KW-2149 (3) and BMS-181174 (4), was designed to activate under nucleophilic and reductive conditions. Successive nucleophile-mediated disulfide cleavage transformations of 9 are expected to generate thiol species ideally positioned to render the two mitomycin systems vulnerable to nucleophilic attack and permit DNA interstrand cross-link formation. The dithiane linker, strategically positioned between the two mitomycins, distinguished 9 from 3 and 4. Nucleophilic activation of this cyclic disulfide permitted both activated mitomycins to remain tethered to one another. We report the synthesis of 9, and show that the nucleophile Et3P markedly enhances the activation and consumption of 9, compared with the reference compound 7-N, 7â²-Nâ²-(cyclohexanyl-trans-1â³,4â³-dimethylenyl)bismitomycin C (27). We further demonstrated that 9 provides higher levels of DNA interstrand cross-links than either the dimeric reference compounds, 27 and 7-N,7-Nâ²-(2â³,5â³-dihydroxy-1â³,6â³-hexanediyl)bismitomycin C (28), or the monomeric mitomycins, 1 and 3, when Et3P is added to solutions containing EcoRI-linearized pBR322 DNA.
能够修饰互补 DNA 链的二聚烷基化剂引起了人们的极大兴趣。我们制备了新型二聚丝裂霉素--7-N,7â²-Nâ²-(1â³,2â³-二噻烷基-3â³,6â³-二亚甲基)双丝裂霉素 C (9),其中丝裂霉素由一个二噻烷单元桥接。二聚体 9 与临床测试的无环二硫化物 KW-2149 (3) 和 BMS-181174 (4) 一样,都是在亲核和还原条件下激活的。9 在亲核剂介导下连续发生二硫裂解转化,预计会产生硫醇物种,从而使两种丝裂霉素系统易受亲核攻击,并允许 DNA 链间交联的形成。二噻烷连接体位于两种丝裂霉素之间,具有战略意义,使 9 号与 3 号和 4 号区别开来。这种环状二硫化物的亲核活化使得两种活化的丝裂霉素能够彼此保持连接。我们报告了 9 的合成过程,并表明与参考化合物 7-N、7â²-Nâ²-(环己基-反式-1â³,4â³-二甲苯基)双丝裂霉素 C(27)相比,亲核剂 Et3P 能显著提高 9 的活化和消耗。我们还进一步证明,与二聚参比化合物 27 和 7-N,7-Nâ²-(2â³,5â³-二羟基-1â³,6â³-己二基)霉素 C(28)或单体丝裂霉素 1 和 3 相比,当向含有 EcoRI 线性化 pBR322 DNA 的溶液中加入 Et3P 时,9 能提供更高水平的 DNA 链间交联。