Design,Synthesis And Activity Of Novel Anti-Fatigue Molecules Based On AMPA Receptor

Fatigue is a sub-health state which is caused by many factors such as excessive physical exertion,lack of sleep,excessive mental exertion,diseases and so on.It is a comprehensive physiological and psychological process characterized by subjective weakness,inability to concentrate,slow thinking,and inability to maintain various physiological functions in a normal state,which leads to the decline of work and learning efficiency and seriously affects people’s quality of life.Fatigue exists in a wide range of people and endangers their physical and mental health.Therefore,it is of important theoretical significance and practical value to develop the drugs with less adverse effect for relieving fatigue.Theα-Amino-3-hydroxy-5-methyl-4-isoxazolpropionic acid（AMPA）is one major type of excitatory ionic glutamate receptors in the central nervous system,and it exerts vital functions on the membrane of neurons.It is an important form of synaptic plasticity in memory formation that the positive allosteric modulator of AMPA receptor stabilizes the active conformation of AMPA receptor and enhances synaptic current to promote synaptic transmission.AMPA receptor is now an important target for the treatment of neurological and mental diseases which is involved in a variety of neural activity processes.As a positive allosteric regulator of AMPA receptor,1-（1,3-benzodioxin-5-ylcarbonyl）-piperidine（1-BCP）can regulate AMPA receptor gated ion current,allosterically bind with glutamate receptor（glu A1-glu A4）subunit and limit desensitization,which can alleviate fatigue and improve cognition.Based on 1-BCP as parent structure,5 representative structural types were designed as AMPA receptor modulators using the classical drug design theory.The docking results of the structure with AMPA receptor protein indicated that most compounds have low binding free energy and strong binding force with AMPA receptor,which verified the rationality of structural design.A total of 34 compounds were synthesized,and their structures were confirmed by ~1H NMR,¹³C NMR and HRMS.Among them,19 compounds were novel compounds.The central excitabilities of the synthesized compounds were preliminarily evaluated by the hypnotic test of pentobarbital sodium in mice.Anti-fatigue activities of compounds were evaluated by weight-bearing swimming test and measure of biochemical indexes of swimming induced fatigue in mice.The comprehensive analysis of the experimental results showed that:compounds F3,F5 and F6 were worthy of further study.Compounds F5 and F6 significantly reduced the sleep time induced by pentobarbital sodium,prolonged the weight-bearing swimming time of mice,inhibited the changes of BUN,MG and LG caused by fatigue（P<0.05）.And F3significantly prolonged the weight-bearing swimming time of mice,reduced the contents of BUN and LA（P<0.05）.The preliminary structure activity relationship analysis showed that the amide bridge in the lead compound might be an inactive essential group,which could be replaced by sulfonamide bridge.This was conducive to the formation of hydrogen bonds with amino acid residues,so that the ligand went deep into the receptor cavity and bound more closely.It was also found that Lys251 amino acid residue could be used as a key site.The prominent anti-fatigue effect of 2,4,5-trimethoxybenzamides indicates that the conpound with more methoxy groups on the benzene ring has the stronger the anti-fatigue activity.Among the nitrogen-containing heterocycles,N,N-diethylpip-erazine-1-formamide and（2-methoxyphenyl）（piperazine-1-yl）ketone contribute more to the anti-fatigue activity.The results of our research provide an important reference for the design and synthesis of new structural types of anti-fatigue molecules and thus the discovery of safe and efficient anti-fatigue active molecules.