Design,Synthesis And Biological Evaluation Of Novel Multitargeting Anti-AD Iron Chelators

Recently,with the increasing incidence of Alzheimer's disease?AD?,the development of potent and safe anti-AD drugs is imminent.Given the complex pathogenesis of AD,multitarget-directed ligands?MTDLs?strategy has become the current research and development trend of new anti-AD small molecule active compounds.This project is mainly based on the two targets of iron ion and monoamine oxidase-B?MAO-B?,with 3-hydroxypyridine-4-ones?3,4-HPOs?iron chelators as the main pharmacophore parent nucleus.The coumarin compounds and safinamide analogs with MAO-B inhibitory activity were combined with 3,4-HPOs based on MTDLs strategies,ligand-based and receptor-based drug design methods,etc.Finally,two classes of multi-target anti-AD compounds with iron chelation activity,MAO-B inhibitory activity,potential antioxidant and anti-A?aggregation were designed and synthesized,the related in vitro and in vivo activities were also determined.This thesis consists of seven parts:The first chapter comprehensively summarized the main contents related to this paper,including the pathogenesis of AD,the development of anti-AD drugs,the design method of MTDLs strategies,the physiological and pathological mechanism of iron,the classification and development of iron chelators,the advantages of hydroxypyridinones?HPOs?iron chelators and their application in AD,the introduction of MAO and the development of MAO-B inhibitors,and elaborated the significance and the innovation of this paper.In chapter 2,the design and synthesis of the first-class compounds——3-amide-coumarin-HPO hybrids were described.The synthetic routes were explored and the reaction conditions were optimized.In particular,the synthesis method of amide and the selective deprotection reaction of the final step increased the difficulty of the synthesis of this kind of compounds.Therefore,after repeated attempts and optimization,there were totally 105 synthetic intermediates and 33 target compounds were obtained finally.In chapter 3,the in vitro and in vivo biological activities and drug-likeness of the first-class compounds were evaluated,and the SAR was discussed and summarized.All compounds showed good iron chelation activity.The p Fe³⁺values were between16.91 and 20.16.The p Fe³⁺values of 21 compounds were higher than that of the control drug deferiprone?DFP,17.50?.Among them,compounds 89d,91y and 91z were promising with p Fe³⁺values of 18.93,18.98 and 20.16,respectively.The inhibition ratio of all compounds against MAO-B at 100 n M was also determined.Among them,the inhibition ratio of 26 compounds was higher than 40%,20compounds were higher than 45%and 2 compounds were higher than 50%.After determined the IC₅₀,we found that the IC₅₀ values of 3 compounds were lower than the positive drug?pargyline:107.3 n M?,which were respectively 89d?87.9 n M?,91i?100.2 n M?and 91w?98.6 n M?,among which 89d was the optimal compound.The molecular docking of compound 89d was performed to elucidate its possible binding mode with MAO-B.Then,the cytotoxicity,anti-A?and antioxidant activity of compound 89d were measured.The compound had almost no cytotoxicity and showed significant anti-A?and antioxidant activity.Finally,it was found that this compound can significantly ameliorate the cognitive impairment of mice,which was better than the positive drugs?pargyline and tacrine?.Therefore,it can be concluded that compound 89d in this class is an excellent multi-target lead compound with potential anti-AD activity.In chapter 4,the design and synthesis of the second-class compounds——benzamide-HPO hybrids were described.The synthetic routes were explored and the reaction conditions were optimized.The synthesis method of amide was the same as that of the first-class compounds,but the selective deprotection reaction in the final step still increased the difficulty of the synthesis.Therefore,after repeated attempts and optimization,there were totally 45 synthetic intermediates and 28 target compounds were obtained finally.In chapter 5,the biological activities and drug-likeness of the second class compounds were evaluated,and the SAR was discussed and summarized.All compounds also showed good iron chelation activity.The p Fe³⁺values were between18.13 and 19.39.The p Fe³⁺values of 26 compounds were higher than that of the control drug DFP?18.24?and 6 compounds were higher than 19.00.Among them,compounds 99g,99l and 99u were promising with p Fe³⁺values of 19.31,19.39 and19.35,respectively.The inhibition ratio of all compounds to MAO-B at 1?M and 100n M were also determined.The inhibition ratio of all compounds was higher than 50%at 1?M.At 100 n M,the inhibition ratio of 13 compounds was higher than 45%and 5compounds?99a,99g,99i,99l and 99m?were higher than 50%.After determined the IC₅₀ values,we found that the IC₅₀ values of 6 compounds were lower than the positive drug?pargyline:107.3 n M?,which were respectively 99a?79.0 n M?,99g?68.4 n M?,99i?89.1 n M?,99l?96.4 n M?,99m?82.8 n M?and 99q?93.8 n M?,among which 99g was the optimal compound and 99a was the second.The molecular docking of compound 99g showed that this compound has a stronger binding mode and showed a better inhibitory activity,and the drug-like properties also showed better than series I.Therefore,compound 99g in this class is an excellent multi-target lead compound with potential anti-AD activity.The sixth chapter was the experimental part,which described the synthesis methods of each step,data characterization of all compounds,and the experimental methods of the related in vitro and in vivo tests.Finally,in chapter 7,we summarized and made a prospect for the whole thesis.In this paper,two classes of novel multi-target anti-AD iron chelators were designed and synthesized based on 3,4-HPOs.A complete method for activity determination and structure-activity relationships were established.Finally,two superior compounds were obtained,which laid a foundation for further researches and development of multi-target anti-AD compounds.