Studies on the formation of reactive intermediates from the antineoplastic agentN,N′Bis(2-chloroethyl)-N-nitrosourea (BCNU)in vitro andin Vivo. Characterization of novel glutathione adducts by ionspray tandem mass spectrometry
作者:Margaret R. Davis、Thomas A. Baillie
DOI:10.1002/jms.1190300111
日期:1995.1
In a study designed to examine the nature of short-lived, electrophilic intermediates liberated during decomposition of N,N′-bis(2-chloroethyl)-N-nitrosourea (BCNU) in vitro and also on administration of BCNU (140 μmol i.p.) to rats in vivo, both on-line and off-line LC/MS/MS techniques were employed to detect and characterize the corresponding glutathione (GSH) adducts present in incubation media and excreted into bile, respectively. In vitro, four GSH conjugates were formed and these were identified, on the basis of their product ion spectra, as products of S-and N-carbamoylation and alkylation reactions. Although the relative proportions of these in vitro adducts were found to depend on the molar ratios of GSH and BCNU, the major adduct under all conditions studied proved to be S-(2-chloroethylcarbamoyl)glutathione (SCG). Analysis of untreated bile samples by means of on-line LC/MS/MS with constant neutral loss (129 u) and precursor ion (m/z 179) scanning techniques again led to the detection of four GSH conjugates, although only one of these (SCG) was common to the group of adducts identified in vitro. All of the GSH conjugates detected in bile represented products of S-carbamoylation, indicating that the alkylating moiety released from BCNU undergoes reactions in vivo with nucleophiles other than GSH.
在一项旨在研究N,N'-双(2-氯乙基)-N-亚硝基脲(BCNU)在体外分解过程中释放的短寿命、亲电性中间体的性质以及BCNU(140μmol,腹腔注射)在体内对大鼠的影响的研究中,采用了在线和离线的液相色谱-质谱-质谱(LC/MS/MS)技术,分别检测和表征了存在于培养介质中和排入胆汁中的相应谷胱甘肽(GSH)加合物。在体外,形成了四种GSH结合物,根据其产物离子谱,这些结合物被鉴定为S-和N-氨甲酰化和烷基化反应的产物。尽管这些体外加合物的相对比例取决于GSH和BCNU的摩尔比,但在所有研究条件下,主要的加合物均为S-(2-氯乙基氨甲酰)谷胱甘肽(SCG)。通过使用具有恒定中性损失(129u)和母体离子(m/z 179)扫描技术的在线LC/MS/MS分析未经处理的胆汁样本,再次检测到了四种GSH加合物,尽管其中只有一种(SCG)与体外鉴定出的加合物组相同。所有在胆汁中检测到的GSH加合物均代表S-氨甲酰化的产物,这表明从BCNU释放出的烷基化部分在体内与除GSH以外的亲核试剂发生了反应。