Design,Synthesis And Structure-activity Relationship Study Of Novel Uracil Derivatives As Dipeptidyl Peptidase-Ⅳ Inhibitors

Objective:Diabetes,as a common metabolic disease,has serious harm to human health.At present,diabetes has become the third largest chronic non-communicable disease after cardiovascular and cerebrovascular diseases and malignant tumors.Type 2 diabetes is the type of diabetes.It is caused by insulin resistance,low insulin secretion and action.Type 2 diabetes not only causes persistent hyperglycemia,but also many chronic complications,such as stroke,angina pectoris,arteriosclerosis and other diseases,and cause damage to the eyes,kidneys,heart,blood vessels and nerves,and even life-threatening.It is particularly significant to develop drugs that can effectively treat diabetes.Glucagon-like peptide-1 and gastric inhibitory peptide are important hormones that can effectively promote insulin secretion and inhibit glucagon secretion in the human body,and play an important role in lowering blood sugar.But there is also an enzyme capable of degrading these two proteins,dipeptidyl peptidase-IV.Dipeptidyl peptidase-IV can lead to rapid metabolism and inactivation of glucagon-like peptide-1 and gastric inhibitory peptide in vivo,making it difficult to achieve the effect of lowering blood sugar.Studies have shown that by inhibiting the activity of dipeptidyl peptidase-IV,the metabolic inactivation of glucagon-like peptide-1 and gastric inhibitory peptide can be effectively avoided to achieve the purpose of lowering blood sugar.And this hypoglycemic method is mild,safe,has few side effects,and hardly causes hypoglycemia and weight gain.Therefore,dipeptidyl peptidase-IV has become a popular target for the treatment of diabetes.Through molecular docking of dipeptidyl peptidase-IV inhibitor and dipeptidyl peptidase-IV receptor,we found that uracil structure plays an important role in the binding process of ligand and receptor.It is an important structure in which the inhibitor is combined with the key amino acid residues tyrosine 631,tyrosine 547 and arginine 125 in the receptor.Based on this,this project designed and synthesized several series of uracil derivatives with uracil as the core structure,and studied the inhibitory activity of dipeptidyl peptidase-IV in vitro,hoping to obtain higher activity.and bioavailability of dipeptidyl peptidase-IV inhibitors,and hope to provide effective guidance for the further development of new hypoglycemic drugs by summarizing the structure-activity relationship of these compounds.Methods:（1）Compound design:Through the study of the currently marketed dipeptidyl peptidase-IV drugs,we found that alogliptin and linagliptin have a certain similarity in structure,which prompted the exchange of the two drugs in structure Therefore,this paper finally uses the pyrimidinedione structure in alogliptin as the basic skeleton,and chooses to replace the cyanobenzyl structure of alogliptin with the butynyl structure in linagliptin,through molecular splicing Principle A novel compound and its derivatives containing 1-but-2-ynyl-pyrimidine-2,4-dione structure were designed.（2）Compound synthesis:In this paper,4 series of derivatives were designed and synthesized through substitution,hydrolysis,condensation and other reactions using6-chlorouracil,which is cheap and easily available in industry.Series 1 and Series 2:Group substitution was carried out on the N-3 site of uracil,and the effect of different types of groups substituted at the N-3 position on the activity was discussed;Series 3:The C-6 site of uracil was modified,and the effect of substituting different types of groups at the C-6 position on the activity was discussed;Series 4:Further structural optimization is carried out for the compounds with the best activity obtained in the above series to obtain inhibitors with better activity.The structures of the above compounds have been confirmed by ¹H NMR,¹³C NMR and ESI MS data.（3）Activity studies:Using alogliptin as a positive control,the inhibitory effect of the compounds on DPP-4 enzyme was studied,and its OD value was measured by a microplate reader at a wavelength of 405 nm,and the inhibitory rate of the compounds was calculated according to the inhibition rate calculation formula.Using the prism6 software to calculate the IC₅₀value of the compounds.（4）Molecular docking:Through molecular docking,the interaction mode between the compound and the enzyme was preliminarily explored,and the inhibitory effect of the compound was further verified by calculating the binding free energy.Results:（1）56 uracil derivatives were synthesized,and the inhibitory activity of the derivatives on dipeptidyl peptidase-IV was evaluated.（2）Summarized and perfected the structure-activity relationship of uracil DPP-4inhibitors,and obtained compounds 4p,4q,4r,4u,12a,and 12b that have better in vitro activity than the positive drug Alogliptin.（3）We have revealed the binding mode of compounds and proteins through molecular dockingConclusion:Finally,we obtained 6 uracil derivatives with strong DPP-4 inhibitory ability and lower toxicity,and combined with molecular docking to reveal the binding site between the inhibitor and the receptor.It is confirmed that the importance of the（R）-3-aminopiperidine structure of the compound in exerting its inhibitory effect,and the interchange of the two groups of butynyl and cyanobenzyl in drug design is feasible.It shows that the bicyclic aromatic heterocyclic group is suitable to be introduced at the N-3 site of uracil,and it is revealed that the N-3 site has great potential in compound structure design.This study will provide directions for the design of such inhibitors in the future,and the obtained structure-activity relationship will also help the development of such hypoglycemic agents.