Design,Synthesis And Preliminary Activity Assay Of Indoleamine-2,3-dioxygenase Inhibitors

Indoleamine 2,3-dioxygenase?IDOs?is a heme-containing protein that catalyzes the oxidative cleavage of the tryptophan indole ring via the kyn?renine pathway.The formation of N-formyl-kyn?renine is the first rate-limiting step in this pathway.The indoleamine 2,3-dioxygenase?IDOs?family incl?des two related s?btypes of enzymes,namely IDO1 and IDO2,which have abo?t 60%seq?ence similarity and different biochemical characteristics.IDO1 and IDO2 are widely expressed in macrophages and dendritic cells to exert imm?nomod?latory f?nctions.Indoleamine2,3-dioxygenase?IDO1?mediates a variety of imm?nomod?latory processes,incl?ding the ind?ction of activation and differentiation of reg?latory T cells,inhibition of T cell imm?ne responses,and f?nctional differentiation of dendritic cells,thereby impeding the development of t?mors.The imm?ne cells recognize and promote t?morgrowth.Therefore,this enzyme is widely considered as an important target for small molec?le dr?gs for t?mor imm?notherapy.In the past 20 years,a large n?mber of effective IDO1 inhibitors have been discovered.Among them,indoximod,epacadostat and NLG919 entered into the clinical trials for f?rther development.In o?r st?dy,epacadostat was?sed as the lead compo?nd.With the help of comp?ter-aided dr?g design technology,the crystal str?ct?re of IDO1 with vario?s IDO1 inhibitors was analyzed and new scaffolds were proposed.Therefore,?sing effective and practical dr?g design methods s?ch as bio-isosteresis and skeleton transitions,combined with modern comp?ter-aided dr?g design methods,we designed,synthesized,and validated a total of 55 target compo?nds and related intermediates and positive controls of 4 types with novel str?ct?res and excellent res?lts.All of the target compo?nds were tested for melting point and confirmed by n?clear magnetic resonance spectroscopy and carbon-13 spectroscopy.The inhibitory activity of the enzyme was determined by HPLC-MS/MS method to determine the concentration of s?bstrate tryptophan and prod?ct kyn?renine.The test res?lts show that all compo?nds have a certain degree of indoleamine 2,3-dioxygenase activity.Among them,f?razolidinones,pyridopyrimidines,benzof?rans,acetophenone oximes showed the best activity,which is comparable to or even better than that of the positive control.Three cell lines,Hep G2 cells,A459 cells,and B16F10 cells,were?sed to determine cell viability by MTT colorimetry.These res?lts show that the compo?nds we synthesized have a certain degree of t?mor killing capacity,and compo?nd III₂ and III₄ demonstrated better activity than cisplatin,which hasgreat val?e for f?rther research.Some selected compo?nds with good in vitro activity for enzyme inhibition was cond?cted docking st?dies to sim?late the interaction between the enzyme and the small molec?le inhibitor to acc?rately analyze the interaction site and action relationship between the enzyme and the small molec?le inhibitor.It lays a solid fo?ndation for the in-depth development of str?ct?ral optimization and biological eval?ation of the active compo?nds of IDO1 inhibitors.