Design,Synthesis And Biological Activity Of Carbamates As Novel TRPV1-antagonist/FAAH Inhibition Dual-target Compounds

Contrary to the usually treatable acute pain that suddenly occurs due to specific injuries,chronic pain has a long duration,is difficult to treat,and has limited efficacy.In addition,repeated or prolonged exposure to pain stimuli can make the central nervous system sensitive,exacerbating pain and chronic diseases.Due to the complexity of pain pathophysiology,most current analgesic drugs that only act on one target,including opioids and non-steroidal anti-inflammatory drugs,often have unsatisfactory efficacy and side effects.In recent years,there has been increasing interest in developing dual acting or multifunctional ligands that simultaneously regulate multiple targets.Compared to single target drugs,they may have multiple advantages such as better therapeutic efficacy and/or safety.Therefore,focusing on endogenous pain pathways and receptors or ion channels expressed in pain receptors,and developing drugs that regulate two or more related targets may lead to synergistic therapeutic effects in pain treatment.Fatty acid amide hydrolase(FAAH)is a membrane binding protein belonging to the serine hydrolase family,which is responsible for hydrolysis of a class of bioactive lipids called fatty acid amides in the central nervous system and surrounding tissues.It can regulate many physiological functions,including pain,inflammation,depression,anxiety,and neurodegeneration,by hydrolyzing endogenous cannabinoids,so inhibiting FAAH can produce a therapeutic effect that suppresses pain.Unfortunately,the increase in AEA in vivo caused by FAAH inhibition can further activate transient receptor potential receptor 1(TRPV1).TRPV1 is a member of the transient receptor potential(TRP)channel family,which mediates the generation and conduction of pain.It can be activated by various physical and chemical stimuli such as protons(p H<5.5),harmful heat(>42 ℃),capsaicin,and endogenous lipids such as Anandamide,N-acyldopamine.So although using FAAH inhibitors alone can produce analgesic effects by increasing AEA,it also has the side effect of activating TRPV1.The same is true,existing FAAH inhibitors have been discontinued in clinical trials due to their ineffectiveness.If FAAH is inhibited while antagonizing TRPV1,it can inhibit the increase of endogenous cannabinoids in FAAH to produce analgesic effects without activating TRPV1.This synergistic effect can produce stronger analgesic effects.Given this background,developing dual target compounds that simultaneously inhibit FAAH and antagonize TRPV1 may become ideal drugs for treating pain.In this subject,based on the principle of pharmacophore combination,Melatonin,Evodiamine and a series of basic activity pharmacophore of highly effective TRPV1 antagonists synthesized by our research group in the earlier stage were compared with URB597,JZL-195 ω-The active pharmacophore of tetrazolyl alkyl carbamate and other FAAH inhibitors are linked to synthesize a series of new carbamate TRPV1antagonistic/FAAH inhibitory double target compounds.In vitro activity evaluation experiments,compounds 7,33,41,and 42 showed good antagonistic and inhibitory activities against TRPV1 and FAAH.In the evaluation of in vivo analgesic activity,compound 42 showed effective and dose-dependent analgesic activity in both the first stage(acute pain)and the second stage(chronic pain)of formalin induced pain.In the experiment of inflammatory pain and body temperature side effects induced by carrageenan,compound 42 showed excellent anti-inflammatory activity and safe body temperature effect.The results of target participation experiments and molecular docking studies indicate that the analgesic effect produced by compound 42 in vivo comes from TRPV1 antagonism and FAAH inhibition.In addition,molecular docking studies have shown that compound 42 can tightly bind with TRPV1(PDB ID: 5IS0)and FAAH(PDB ID: 3LJ6),further demonstrating the rationality of our design strategy.In summary,dual target compounds that simultaneously antagonize TRPV1 and inhibit FAAH have the potential to be developed as new analgesic drugs.