Demonstration of the Innate Electrophilicity of 4-(3-(Benzyloxy)phenyl)-2-(ethylsulfinyl)-6-(trifluoromethyl)pyrimidine (BETP), a Small-Molecule Positive Allosteric Modulator of the Glucagon-Like Peptide-1 Receptor
作者:Heather Eng、Raman Sharma、Thomas S. McDonald、David J. Edmonds、Jean-Philippe Fortin、Xianping Li、Benjamin D. Stevens、David A. Griffith、Chris Limberakis、Whitney M. Nolte、David A. Price、Margaret Jackson、Amit S. Kalgutkar
DOI:10.1124/dmd.113.052183
日期:2013.8
4-(3-(Benzyloxy)phenyl)-2-(ethylsulfinyl)-6-(trifluoromethyl)pyrimidine (BETP) represents a novel small-molecule activator of the glucagon-like peptide-1 receptor (GLP-1R), and exhibits glucose-dependent insulin secretion in rats following i.v. (but not oral) administration. To explore the quantitative pharmacology associated with GLP-1R agonism in preclinical species, the in vivo pharmacokinetics of BETP were examined in rats after i.v. and oral dosing. Failure to detect BETP in circulation after oral administration of a 10-mg/kg dose in rats was consistent with the lack of an insulinotropic effect of orally administered BETP in this species. Likewise, systemic concentrations of BETP in the rat upon i.v. administration (1 mg/kg) were minimal (and sporadic). In vitro incubations in bovine serum albumin, plasma, and liver microsomes from rodents and humans indicated a facile degradation of BETP. Failure to detect metabolites in plasma and liver microsomal incubations in the absence of NADP was suggestive of a covalent interaction between BETP and a protein amino acid residue(s) in these matrices. Incubations of BETP with glutathione (GSH) in buffer revealed a rapid nucleophilic displacement of the ethylsulfoxide functionality by GSH to yield adduct M1, which indicated that BETP was intrinsically electrophilic. The structure of M1 was unambiguously identified by comparison of its chromatographic and mass spectral properties with an authentic standard. The GSH conjugate of BETP was also characterized in NADPH- and GSH-supplemented liver microsomes and in plasma samples from the pharmacokinetic studies. Unlike BETP, M1 was inactive as an allosteric modulator of the GLP-1R.
4-(3-(苄氧基)苯基)-2-(乙基亚磺酰基)-6-(三氟甲基)嘧啶(BETP)是一种新型的胰高血糖素样肽-1受体(GLP-1R)小分子激活剂,在大鼠体内静脉注射(而非口服)后可表现出葡萄糖依赖性胰岛素分泌。为了在临床前物种中探索与 GLP-1R 激动相关的定量药理学,研究人员在大鼠静脉注射和口服后检测了 BETP 的体内药代动力学。大鼠口服 10 毫克/千克剂量后,血液循环中未检测到 BETP,这表明口服 BETP 在该物种中缺乏促胰岛素作用。同样,大鼠静脉注射(1 毫克/千克)BETP 后的全身浓度极低(零星)。啮齿动物和人类的牛血清白蛋白、血浆和肝脏微粒体的体外培养表明,BETP 易于降解。在没有 NADP 的情况下,血浆和肝脏微粒体培养液中检测不到代谢物,这表明 BETP 与这些基质中的蛋白质氨基酸残基之间存在共价作用。在缓冲液中将 BETP 与谷胱甘肽(GSH)进行孵育,发现乙亚砜官能团迅速被 GSH 亲核置换,生成加合物 M1,这表明 BETP 本身具有亲电性。通过将 M1 的色谱和质谱特性与真品标准进行比较,可以明确地确定其结构。BETP 的 GSH 结合物也在 NADPH 和 GSH 补充的肝脏微粒体以及药物动力学研究的血浆样本中进行了表征。与 BETP 不同,M1 作为 GLP-1R 的异构调节剂没有活性。