PF-543, the most potent sphingosine kinase (SK) inhibitor, does not demonstrate effective anticancer activity in some cancer cells, unlike other known SK1 inhibitors. PF-543 has a non-lipid structure with a unique toluene backbone; however, the importance of this structure remains unclear. Therefore, the purpose of this study was to investigate changes in SK inhibitory and anticancer activities and to explore the role of the tolyl group structure of PF-543 through various modifications. We transformed the methyl group of PF-543 into hydrogen, fluorine, and hydroxy. PF-543 derivatives in which the methyl group was substituted by hydrogen and fluorine (compound 5) demonstrated SK1 inhibitory and anticancer activities similar to PF-543. Moreover, we performed molecular modeling studies of PF-543 and compound 5. To assess the metabolic stability of PF-543 and compound 5, we determined their degree of degradation using the liver microsomes of four different animal species (human, dog, rat, and mouse). However, both PF-543 and compound 5 showed poor microsomal stability. Therefore, for the medical applications of PF-543, the structural modifications of its other parts may be necessary. Our results provide important information for the design of additional PF-543 analogs.
PF-543是最有效的鞘氨醇激酶(SK)抑制剂,但在某些癌细胞中并未显示出有效的抗癌活性,与其他已知的SK1抑制剂不同。PF-543具有一个独特的甲苯骨干的非脂质结构;然而,这一结构的重要性尚不清楚。因此,本研究的目的是通过各种修改,调查SK抑制和抗癌活性的变化,并探讨PF-543中甲苯基团结构的作用。我们将PF-543的甲基团转化为氢、氟和羟基。将PF-543中甲基团替换为氢和氟的衍生物(化合物5)显示了与PF-543相似的SK1抑制和抗癌活性。此外,我们对PF-543和化合物5进行了分子建模研究。为了评估PF-543和化合物5的代谢稳定性,我们使用四种不同动物种类(人、狗、大鼠和小鼠)的肝脏微粒体来确定它们的降解程度。然而,PF-543和化合物5都显示出较差的微粒体稳定性。因此,对于PF-543的医疗应用,可能需要对其其他部分的结构进行修改。我们的结果为设计额外的PF-543类似物提供了重要信息。