Design,Synthesis And Anti-Inflammatory Activity Of Pyrimidine And Pyrazole-Pyrimidine Derivatives

Nitric oxide(NO)is a biologically active gas that has multiple roles in innate and adaptive immune responses.In macrophages,nitric oxide is produced by inducible nitric oxide synthase when stimulated by microorganisms and cytokines.It is necessary for host defense against pathogens and immune regulation.Nitric oxide synthase(NOS)produces NO by catalyzing the NADPH-dependent L-arginine(substrate)oxidation.There are three different subtypes of NOS,depending on where it exists,namely neuronal NOS(n NOS,type I),inducible or inflammatory NOS(i NOS,type II)and endothelial NOS(e NOS,type III).The production of NO depends on the size and duration of its production,and it plays a role in both physiology and pathology.The overexpression of i NOS will increase the production of NO,which will eventually react with superoxide radicals to generate reactive nitrogen species(RNS),such as dinitrogen trioxide(N2O3)and peroxynitrite(ONOO-).These RNSs trigger certain inflammation or oxidative stress pathways,leading to various pathological conditions,such as Parkinson’s disease,Alzheimer’s disease,multiple sclerosis,stroke,rheumatoid arthritis,diabetes,celiac disease and inflammation Enteropathy.Mutational analysis of i NOS has identified a collection of amino acids that are critical for the function of the enzyme.When mutated to asparagine,Glu546 lowers the measured inter‐domain electron transfer between the FMN subdomain and heme in the oxygenase domain.In the H4 B binding pocket in the oxygenase domain,residues Arg375,Trp455,Trp457,and Phe470 are crucial for H4 B cofactor binding and subsequent dimerization and function of the enzyme.There are two main types of i NOS inhibitors.One is directly competitive with L-Arg,which can reversibly inhibit the binding of L-Arg or compete with L-Arg,and the other is to inhibit the formation of active i NOS dimers.But so far,they have not passed in clinical trials,so it is necessary to synthesize effective i NOS inhibitors.In order to discover and develop anti-inflammatory drugs for arthritis,the "Hit" that we found on the basis of the past has a strong toxicity disadvantage.The compound is docked with inducible nitric oxide synthase(PDB ID: 1DD7),and the position that can be modified is found through the spatial structure and the interaction mode of the ligand and the protein.Through analysis,a total of 40 new pyrimidines,pyrazolo[4,3-d]pyrimidine derivatives were synthesized,and the anti-inflammatory activity to NO and the toxicity to normal liver cells(LO2)were screened,and the balance between toxicity and activity relationship.Summarizing through multiple steps,it is found that the title compound 6e has lower toxicity(respectively for LO2: IC50>1000μM)and effective effect on inhibiting NO release(77% at 10μM).