Bednarski P J, Trümbach B, Kratochwil N A, Schönenberger H
Lehrstuhl für Pharmazeutische Chemie II, Universität Regensburg, Germany.
J Med Chem. 1992 Nov 13;35(23):4479-85. doi: 10.1021/jm00101a027.
The stability of the five-membered chelate ring of the cisplatin analogue [meso-1,2-bis(2,6-dichloro-4- hydroxyphenyl)ethylenediamine]dichloroplatinum(II) was investigated under typical cell culture conditions (IMEM-Richter's medium with 10% fetal calf serum, 37 degrees C). For this purpose, the platinum compound was radiolabeled with tritium in the meta position of the aromatic ring by an acid-catalyzed tritium-exchange reaction, and a reversed-phase HPLC assay with radiochemical detection was developed to monitor for the presence of the free diamine ligand in the cell culture medium. A gradual increase in radioactivity attributed to the free diamine was found in medium containing the dichloroplatinum(II) complex (ca. 25% after 24 h), indicating that the diamine ligand was being released from the metal atom. When 1 mM glutathione (GSH) was included in the incubation medium, the amount of free diamine nearly doubled after 24 h, while the amount of radioactivity attributed to serum protein-platinum adducts decreased relative to incubations without GSH. On the other hand, the omission of serum from the incubations resulted in a dramatic decrease in the amount of radioactivity eluting under the diamine peak, while the concentrations of the two methionine-Pt adducts, which formed in a 1:1 ratio, rose. Through the use of liquid secondary ion mass spectroscopy, the two methionine-Pt adducts were identified as monomethionine metabolites of the title compound, whereby the two chloride ligands have been replaced by the amino acid. These compounds are probably diastereomers since the sulfur of methionine can coordinate to platinum with equal probability either cis or trans to the R-configured benzylamine carbon. On the basis of the chemical shifts of the MeS groups in the 250-MHz 1H NMR, it is concluded that a S,N-five-membered chelate ring is present in these methionine-Pt adducts.
在典型的细胞培养条件下（含10%胎牛血清的IMEM - 里氏培养基，37摄氏度），对顺铂类似物[内消旋 - 1,2 - 双(2,6 - 二氯 - 4 - 羟基苯基)乙二胺]二氯铂(II)五元螯合环的稳定性进行了研究。为此，通过酸催化的氚交换反应，使铂化合物在芳环的间位用氚进行放射性标记，并开发了一种具有放射化学检测的反相高效液相色谱法，以监测细胞培养基中游离二胺配体的存在。在含有二氯铂(II)配合物的培养基中，发现归因于游离二胺的放射性逐渐增加（24小时后约为25%），这表明二胺配体正从金属原子上释放出来。当在孵育培养基中加入1 mM谷胱甘肽(GSH)时，24小时后游离二胺的量几乎增加了一倍，而归因于血清蛋白 - 铂加合物的放射性量相对于未添加GSH的孵育情况有所下降。另一方面，孵育时省略血清会导致二胺峰下洗脱的放射性量急剧下降，而以1:1比例形成的两种甲硫氨酸 - 铂加合物的浓度则上升。通过使用液体二次离子质谱法，将这两种甲硫氨酸 - 铂加合物鉴定为标题化合物的单甲硫氨酸代谢物，其中两个氯配体已被氨基酸取代。这些化合物可能是非对映异构体，因为甲硫氨酸的硫可以以相等的概率与铂顺式或反式配位到R - 构型苄胺碳上。根据250 - MHz 1H NMR中MeS基团的化学位移，得出结论：这些甲硫氨酸 - 铂加合物中存在S,N - 五元螯合环。
