Department of Physical Pharmacy and Pharmacokinetics, Poznan University of Medical Sciences, Poznań, Poland.
J Chromatogr B Analyt Technol Biomed Life Sci. 2013 Apr 1;923-924:92-7. doi: 10.1016/j.jchromb.2013.02.012. Epub 2013 Feb 19.
For the last decade an alkylating agent treosulfan (TREO) has been successfully applied in clinical trials in conditioning prior to hematopoietic stem cell transplantation. Pharmacological activity of the pro-drug depends on its epoxy-transformers, monoepoxide (S,S-EBDM) and diepoxide (S,S-DEB), which are formed in a non-enzymatic consecutive reaction accompanied by a release of methanesulfonic acid. In the present study partition coefficient n-octanol/water (POW) of TREO as well as its biologically active epoxy-transformers was determined empirically (applying a classical shake-flask method) and in silico for the first time. In vitro the partition was investigated at 37°C in the system composed of the pre-saturated n-octanol and 0.05 M acetate buffer pH 4.4 adjusted with sodium and potassium chloride to ionic strength of 0.16 M. Concentration of the analytes was quantified by reversed-phase high performance liquid chromatography (RP-HPLC) method in which retention time increased from S,S-DEB to TREO. It was shown that neither association nor dissociation of the tested compounds in the applied phases occurred. Calculated logPOW (TREO: -1.58±0.04, S,S-EBDM: -1.18±0.02, S,S-DEB: -0.40±0.03) indicate the hydrophilic character of the all three entities, corresponding to its pharmacokinetic parameters described in the literature. Experimentally determined logPOW of the compounds were best comparable to the values predicted by algorithm ALOGPs. Interestingly, the POW values determined in vitro as well as in silico were inversely correlated with the retention times observed in the endcapped RP-HPLC column. It might be explained by the fact that a cleavage of methansulfonic acid from a small molecule of TREO generates significant changes in the molecular structure. Consequently, despite the common chemical origin, TREO, S,S-EBDM and S,S-DEB do not constitute a 'congeneric' series of compounds. We concluded that this might occur in other low-weight species, therefore measurement of their POW by RP-HPLC had to be applied with a special care.
在过去的十年中，一种烷化剂噻替派（TREO）已成功应用于造血干细胞移植前的临床研究。前药的药理活性取决于其环氧转化剂单环氧（S，S-EBDM）和双环氧（S，S-DEB），它们在非酶连续反应中形成，伴随着甲磺酸的释放。在本研究中，首次通过经典摇瓶法和计算方法确定了 TREO 及其生物活性环氧转化剂的正辛醇/水分配系数（POW）。在 37°C 下，在由预饱和正辛醇和 0.05 M 乙酸盐缓冲液 pH 4.4 组成的体系中进行了体外分配研究，该缓冲液用氯化钠和氯化钾调节至离子强度为 0.16 M。通过反相高效液相色谱法（RP-HPLC）定量分析分析物的浓度，其中保留时间从 S，S-DEB 增加到 TREO。结果表明，在所应用的相之间，测试化合物既没有缔合也没有离解。计算的 logPOW（TREO：-1.58±0.04，S，S-EBDM：-1.18±0.02，S，S-DEB：-0.40±0.03）表明所有三种物质都具有亲水性，与其在文献中描述的药代动力学参数相对应。实验测定的化合物的 logPOW 与算法 ALOGPs 预测的值最匹配。有趣的是，体外和体内测定的 POW 值与在端封 RP-HPLC 柱中观察到的保留时间呈反比相关。这可能是由于从 TREO 的小分子中裂解甲磺酸会导致分子结构发生重大变化。因此，尽管具有共同的化学起源，但 TREO、S，S-EBDM 和 S，S-DEB 并不构成“同系物”系列化合物。我们得出的结论是，这种情况可能会在其他低体重物种中发生，因此必须特别注意通过 RP-HPLC 测量它们的 POW。
