Wei Xiaohui, Dai Guowei, Liu Zhongfa, Cheng Hao, Xie Zhiliang, Marcucci Guido, Chan Kenneth K
Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA.
AAPS J. 2006;8(4):E743-55. doi: 10.1208/aapsj080484.
GTI-2040 is a 20-mer phosphorothioate oligonucleotide, which is complementary to the messenger ribonucleic acid (mRNA) of the R2 subunit of ribonucleotide reductase. This study characterized both the in vivo and in vitro metabolism of GTI-2040. A highly specific ion-pair reversed-phase electrospray ionization (IP-RP-ESI) liquid chromatography-mass spectrometry (LC-MS) method was used for the identification of GTI-2040 and metabolites from a variety of biological samples including exonuclease enzyme solutions, plasma, urine, mouse liver/kidney homogenates, and human liver microsomes. Progressively chain-shortened metabolites truncated from the 3' terminal of GTI-2040 were detected in all of the evaluated biological samples. GTI-2040 was found to be a good substrate for 3' but not 5' exonuclease. While the pattern of n-1 chain-shortened 3'-exonucleolytic degradation was similar in the mouse liver and kidney homogenates, the latter was found to contain a larger number of shortenmers, the kidneys appeared to possess higher enzymatic reactivity toward GTI-2040. Thus, metabolism of GTI-2040 was found to occur in a variety of biological samples, mainly mediated by the 3' exonuclease.
GTI-2040是一种20聚体硫代磷酸酯寡核苷酸，与核糖核苷酸还原酶R2亚基的信使核糖核酸（mRNA）互补。本研究对GTI-2040的体内和体外代谢进行了表征。采用高特异性离子对反相电喷雾电离（IP-RP-ESI）液相色谱-质谱（LC-MS）方法，从多种生物样品中鉴定GTI-2040及其代谢产物，这些样品包括核酸外切酶溶液、血浆、尿液、小鼠肝/肾匀浆和人肝微粒体。在所有评估的生物样品中均检测到从GTI-2040的3'末端逐步截短的代谢产物。发现GTI-2040是3'核酸外切酶而非5'核酸外切酶的良好底物。虽然在小鼠肝和肾匀浆中，n-1链缩短的3'-核酸外切酶降解模式相似，但发现后者含有更多的截短产物，肾脏对GTI-2040似乎具有更高的酶活性。因此，可以发现GTI-2040在多种生物样品中发生代谢，主要由3'核酸外切酶介导。
