Synthesis Of BMT Derivatives And Their Inhibitory Effect On Acetylcholinesterase

Alzheimer’s disease（AD）is a kind of disease characterized by mental deterioration and behavior and personality changes.AD patients are common in the middle and old people with cerebral disorder.Acetylcholinesterase（ACh E）inhibitors are now the principal preventive and therapeutic drugs of AD.Among those inhibitors,tacrine（THA）is widely used,which showed not only a desirable inhibitory activity,but also obvious hepatic toxicity.In the current paper,camphor,a monoterpene derivative,was used as a precursor to synthesize bridge methylene tacrine（BMT）,which was further used to produce a series of coumarin-BMT complexes and N-benzyl-BMT heterozygotes by means of substructure splicing.The inhibitory activity of these BMT derivatives on ACh E was determinaed,and two compounds（2-35 and 2-38）with high activity were found.The present paper provided guides for the research and development of functional food components and medicines with inhibitory activity against ACh E.The main results and conclusions of this paper are as follows:（1）Synthesis of BMT:The natural camphor was cyclized with O-aminobenzonitrile under the catalysis of anhydrous aluminum trichloride.After the removal of aluminum salts by the circumfluence of sodium hydroxide solution,the target compounds were obtained,which were further identified as BMT by the determination of ¹H NMR,¹³C NMR and HRMS.（2）Synthesis of coumarin-BMT complexes:By introducing different methylene number length chain bridges on the amino sites of the BMT,coumarins were linked to the BMT,and 21 novel coumarin-BMT complexes are obtained.Via verification of ¹H NMR,¹³C NMR and HRMS spectroscopy,those obtained compounds were identified as target products.（3）Synthesis of N-benzyl-BMT complexs:Benzyl groups with different substituents（F,Cl,Br,I,Me and OMe）in its meta-position or para-position were introduced to BMT on the amino sites of BMT,which generated 21 novel N-benzyl-BMT complexs.The result of structural identification and characterization showed that all obtained compounds were target products.（4）Detection and evaluation of the in vitro inhibitory activity of BMT derivative against ACh E:The detection model of micro ACh E-ATCI reaction system was used to detect and analyze the in vitro inhibitory activity of 34 obtained BMT derivatives,and results indicated that 34 obtained BMT derivatives showed varying inhibitory activities against ACh E.Among coumarin-BMT complexs,inhibitory rate of compounds 2-28,2-31,2-32,2-33,2-35 and 2-38 were relatively high and reached 85.71%,86.68%,81.70%,84.75%,86.60%and 87.48%at the concentration of 2μM,respectively,which were significantly higher than that of Galantamine（69.23%）.With regard to N-benzyl BMT complexs,compounds 3-10 and 3-12 showed relatively high inhibitory rate,which were 68.40%and 68.84%,respectively,but there was no significant difference between the inhibitory rate of 3-10 and 3-12 and that of Galantamine（p<0.05）.In addition,result of enzyme catalyzed kinetic indicated that compounds 2-35 and 2-38exhibited better inhibitory activities and their K_i value reached 49.20 n M and 50.81 n M,respectively,which were significantly higher than that of Galantamine（61.93 n M）.（5）Structure-activity analysis on the inhibition of BMT derivatives against ACh E:In order to elucidate the structure-activity relationship between the BMT derivatives structure and their inhibitory activity against ACh E,the activity detection result of 34BMT derivatives was further analyzed,and result indicated that the structure difference between those BMT derivatives had significant impacts on their inhibitory activity against ACh E.Among coumarin-BMT complexes,the complexes with 5 and 6methylene chain bridges showed a significantly higher inhibitory activity than those complexes with 7 methylene chain bridges.In addition,coumarin-BMT complexes with methoxy group exhibited a desirable inhibitory activity,and those complexes showed higher inhibitory activity with methoxy group on their 6-position than 7-position.Among13 N-benzyl-BMT complexs,they displayed higher inhibitory activity with N-benzyl group on their 3-position than 4-position.Furthermore,their inhibitory activity would be weakened when their 3-position or 4-position was substituted by electron contributing groups（such as Me）,whereas they showed an significant inhibitory activity with electron withdrawing groups on their 3-position（such as F or Br）.In conclusion,34 novel BMT derivatives were synthesized in the current paper which showed diverse inhibitory activities against ACh E.Among those compounds,2-35and 2-38 showed the better inhivitory activity with inhibitory rate up to 86.60%and87.48%at the concentration of 2μM,respectively.Moreover,K_i of 2-35 and 2-38 on ACh E were 49.20 n M and 50.81 n M,respectively,which were significantly lower than that of Galantamine（positive control）.Consequently,compounds 2-35 and 2-38 might have a promising application prospect in functional foods and medicines as ACh E inhibitor.