Discovery of Brain-Penetrative Negative Allosteric Modulators of NMDA Receptors Using FEP-Guided Structure Optimization and Membrane Permeability Prediction

N-Methyl-d-aspartate (NMDA) receptors,
a subtype of ionotropic glutamate receptors in the central nervous
system (CNS), have garnered attention for their role in brain disorders.
Specifically, GluN2A-containing NMDA receptors have emerged as a potential
therapeutic target for the treatment of depressive disorders and epilepsy.
However, the development of GluN2A-containing NMDA receptor-selective
antagonists, represented by N-(4-(2-benzoylhydrazine-1-carbonyl)benzyl)-3-chloro-4-fluorobenzenesulfonamide
(TCN-201) and its derivatives, faces a significant challenge due to
their limited ability to penetrate the blood–brain barrier
(BBB), hampering their in vivo characterization and
further advancement. In this study, we reported a series of 2-((5-(phemylamino)-1,3,4-thiadiazol-2-yl)thio)-N-(cyclohexylmethyl)acetamide derivatives, achieved through
a structure-guided optimization strategy using free energy perturbation
(FEP) and BBB permeability estimation. Through systematic exploration
of various phenyl substitutions, compound 1f emerged
as a standout compound, demonstrating substantially enhanced inhibitory
activity compared with the lead compound TCN-213. Compound 1f not only displayed satisfactory BBB permeability but also showed
antidepressant-like potency in the hydrocortisone-induced zebrafish
depression-like model. All results position it as a promising candidate
for developing innovative therapeutics for NMDA receptor-related disorders.

N-甲基-D-天冬氨酸（NMDA）受体是中枢神经系统（CNS）内离子型谷氨酸受体的一个亚型，因其在脑部疾病中的作用而受到广泛关注。具体而言，含GluN2A亚基的NMDA受体已成为治疗抑郁障碍与癫痫的潜在治疗靶点。然而，以N-(4-(2-苯甲酰肼基-1-羰基)苄基)-3-氯-4-氟苯磺酰胺（TCN-201）及其衍生物为代表的含GluN2A亚基NMDA受体选择性拮抗剂的开发面临重大挑战：这类化合物穿透血脑屏障（BBB）的能力有限，阻碍了其体内表征与进一步研发。本研究报道了一系列2-((5-(苯氨基)-1,3,4-噻二唑-2-基)硫代)-N-(环己基甲基)乙酰胺衍生物，通过采用自由能微扰（FEP）与血脑屏障通透性预测的结构导向优化策略获得。通过对多种苯环取代模式的系统探索，化合物1f脱颖而出，相较于先导化合物TCN-213展现出显著增强的抑制活性。化合物1f不仅表现出良好的血脑屏障通透性，在氢化可的松诱导的斑马鱼抑郁样模型中也显示出类抗抑郁活性。所有研究结果均表明，该化合物有望成为开发NMDA受体相关疾病创新疗法的候选化合物。