Design, synthesis, and evaluation of the pharmacological activity of novel NMDA receptor antagonists based on the germacrone scaffold

The NMDA receptor has long attracted researchers' attention due to its potential as a drug target and its central role in the central nervous system. The NMDA receptor is a ligand-gated and voltage-dependent ion channel widely distributed in the central nervous system. In this study, we employed a drug design strategy combining "molecular assembly" and "combinatorial chemistry." By reducing the carbonyl group of germacrone to a hydroxyl group and esterifying it with alanine and linarinic acid, we successfully obtained nine novel germacrone derivatives through two rounds of structural optimization. We evaluated the neuroprotective activity of these nine derivatives using the MTT assay. The results revealed that compound C1 exhibited particularly outstanding activity, achieving a cell protection rate of 29.63 ± 1.56 % at a concentration of 0.05 μM, outperforming the positive control drug, ifenprodil. Further experiments on NMDA-induced Ca²⁺ influx verified that the action site of compound C1 was the NMDA receptor, and demonstrated its superior antagonistic effect on the NMDA receptor compared to germacrone and ifenprodil. Additionally, molecular docking studies and ADMET property predictions were conducted for compound C1. The results showed that compound C1 tightly bound to the active site of the NMDA receptor and possessed favorable pharmacokinetic properties. In conclusion, compound C1, characterized by a germacrone-linarinic acid structure, not only exhibits strong antagonistic effects on the NMDA receptor but also demonstrates excellent pharmacokinetic properties, indicating its potential for further development as a therapeutic drug for central nervous system diseases.