2-Amino-4-{[3-(carboxymethyl)phenoxy](methoxy)phosphoryl}butanoic acid (GGsTop) is a potent, highly selective, nontoxic, and irreversible inhibitor of γ-glutamyl transpeptidase (GGT). GGsTop has been widely used in academic and medicinal research, and also as an active ingredient (Nahlsgen) in commercial anti-aging cosmetics. GGsTop consists of four stereoisomers due to the presence of two stereogenic centers, i.e., the α-carbon atom of the glutamate mimic (l/d) and the phosphorus atom (R_P/S_P). In this study, each stereoisomer of GGsTop was synthesized stereoselectively and their inhibitory activity against human GGT was evaluated. The l- and d-configurations of each stereoisomer were determined by a combination of a chiral pool synthesis and chiral HPLC analysis. The synthesis of the four stereoisomers of GGsTop used chiral synthetic precursors that were separated by chiral HPLC on a preparative scale. With respect to the configuration of the α-carbon atom of the glutamate mimic, the l-isomer (k_on = 174 M⁻¹ s⁻¹) was ca. 8-fold more potent than the d-isomer (k_on = 21.5 M⁻¹ s⁻¹). In contrast, the configuration of the phosphorus atom is critical for GGT inhibitory activity. Based on a molecular modeling approach, the absolute configuration of the phosphorus atom of the active GGsTop isomers was postulated to be S_P. The S_P-isomers inhibited human GGT (k_on = 21.5–174 M⁻¹ s⁻¹), while the R_P-isomers were inactive even at concentrations of 0.1 mM.

2-氨基-4-{[3-（羧甲基）苯氧基]（甲氧基）磷酰基}丁酸（GGsTop）是一种有效，高选择性，无毒且不可逆的γ-谷氨酰转肽酶（GGT）抑制剂。GGsTop已广泛用于学术和医学研究，并且还用作商业抗衰老化妆品中的活性成分（Nahlsgen）。GGsTop由四个立体异构体组成，这是由于存在两个立体生成中心，即谷氨酸模拟物的α-碳原子（l / d）和磷原子（R _P / S _P）。在这项研究中，立体选择性地合成了GGsTop的每个立体异构体，并评估了它们对人GGT的抑制活性。该升-和d通过手性库合成和手性HPLC分析的组合来确定每种立体异构体的-构型。GGsTop的四种立体异构体的合成使用了手性合成前体，这些前体通过手性HPLC在制备规模上进行了分离。关于谷氨酸模拟物的α-碳原子的构型，l-异构体（k _on  ＝ 174M ^-1  s ^-1）为约。效力比d-异构体高8倍（k _on  = 21.5 M ^-1  s ^-1）。相反，磷原子的构型对于GGT抑制活性至关重要。基于分子建模方法中，活性GGsTop异构体的磷原子的绝对构型，被假定为小号_P。该小号_P -异构体抑制人GGT（ķ_上 = 21.5-174中号^-1 小号^-1），而[R _P -异构体无活性，即使在0.1 mM的浓度。