Aim and Objective: Bacteria could become resistant to β-lactam antibiotics through production of β- lactamase enzymes like metallo-β-lactamase. 2-(2-mercaptoacetamido)-3-phenylpropanoic acid was reported as a model inhibitor for this enzyme. In order to elucidate the mechanism of action in the body’s internal environment, preparation of a labeled version of 2-(2-mercaptoacetamido)-3-phenylpropanoic acid finds importance. In this regard, we report a convenient synthetic pathway for preparation of carbon-14 labeled 2-(2- mercaptoacetamido)-3-phenylpropanoic acid.

Materials and Methods: This study was initiated by using non-radioactive materials. Then, necessary characterization was performed after each of the reactions. Finally, the synthesis steps were continued to produce the target labeled product. For labeled products, the process was started from benzoic acid-[carboxyl- 14C] which has been prepared from barium 14C-carbonate. Chromatography column and NMR spectroscopy were used for purifications and identification of desired products, respectively. Barium [14C]carbonate was purchased from Amersham Pharmacia Biotech and was converted to [14C]benzyl bromide. Radioactivity was determined using liquid scintillation spectrometer.

Results: We used [14C]PhCH2Br which was previously prepared from [14C]BaCO3, H2SO4, PhMgI, LAH and HBr, respectively. To neutralize the [14C]phenylalanine in acidic condition and to reach an isoelectric point of phenylalanine (pH = 5.48), Pb(OH)2 was used. Next, thioacetic acid and bromo acetic acid were used to prepare (acetylthio) acetic acid. A peptide coupling reagent was used in this stage to facilitating amide bond formation reaction between [14C]methyl-2-amino-3-phenyl propanoate hydrochloride and (acetylthio) acetic acid.

Conclusion: Carbon-14 labeled 2-(2-mercaptoacetamido)-3-phenylpropanoic acid via radioactive phenylalanine was obtained with overall chemical yield 73% and radioactivity 65.3 nCi. The labeled target product will be used for in vivo pharmacological studies.

目的和目的：细菌可以通过产生β-内酰胺酶（如金属-β-内酰胺酶）而对β-内酰胺类抗生素产生抗性。据报道2-（2-巯基乙酰胺基）-3-苯基丙酸是该酶的模型抑制剂。为了阐明在人体内部环境中的作用机理，发现标记的2-（2-巯基乙酰胺基）-3-苯基丙酸是很重要的。在这方面，我们报告了一种方便的合成途径，用于制备碳14标记的2-（2-巯基乙酰胺基）-3-苯基丙酸。

材料和方法：本研究是通过使用非放射性材料发起的。然后，在每个反应之后进行必要的表征。最后，继续进行合成步骤以生产目标标记的产物。对于标记产品，该方法从由14C碳酸钡制备的苯甲酸-[羧基14C]开始。色谱柱和NMR谱分别用于纯化和鉴定所需产物。碳酸[14C]碳酸钡购自Amersham Pharmacia Biotech，并转化为[14C]苄基溴。使用液体闪烁光谱仪测定放射性。

结果：我们使用了[14C] PhCH2Br，后者分别由[14C] BaCO3，H2SO4，PhMgI，LAH和HBr制备。为了在酸性条件下中和[14C]苯丙氨酸并达到苯丙氨酸的等电点（pH = 5.48），使用了Pb（OH）2。接下来，使用硫代乙酸和溴代乙酸制备（乙酰硫基）乙酸。在该阶段中使用肽偶联剂以促进[14 C]甲基-2-氨基-3-苯基丙酸酯盐酸盐与（乙酰硫基）乙酸之间的酰胺键形成反应。

结论：通过放射性苯丙氨酸获得了碳-14标记的2-（2-巯基乙酰胺基）-3-苯基丙酸，总化学收率73％，放射性65.3 nCi。标记的目标产品将用于体内药理研究。