Design,Synthesis And Biological Activity Of Novel Substituted Pyrazole Amide Derivatives Based On EcR/USP Complex Structure

The persistent abuse of traditional chemical pesticide had caused a series of problems such as phytotoxicity,resistance,residues and environment pollution.To solve these conundrums,it is really urgent to develop new environment-friendly pesticides,which is also benefit for sustainable development on environmental resources.It is an important method to discover novel green pesticide based on the target.As the target of molting hormone,ecdysone receptor only existed in insect can bind to the molting hormone to effect the growth of insect.Dibenzoylhydrazines(DBHs)are ecdysone agonists with high biological activity,good safety to the non-target animals and environment.Nowadays,only DBHs had been developed as the commercial pesticides.Due to the unique chemical structure,DBHs had caused a series of problems,for example,insect resistance.In order to break the chemical skeleton of DBHs and find novel ecdysone analogs with high activity,in this thesis,several works had been carried out as follows,taking the technology of computer aid drug design(CADD)method that chose ecdysone receptor as target and virtual screen candidate VS008 as lead.1.Five series of compounds and 101 compounds were designed and synthesized based on related literatures and previous work with the optimization of lead VS008,considering on the bind conformation of ligand VS008 in ecdysone receptor.Their insecticidal activities were tested and their common structures were showed as below:2.Comparing the conformations between VS008 and DBH-type compound BYIO6830 in ecdysone receptor,series I containing 32 compounds were designed and synthesized by removing the methylene between pyrazole ring and phenyl ring and considering the bulk effects on N-substituted phenyl ring.Most of Series I showed certain insecticidal activities,several compounds even exhibited better activity than lead VS008.Especially,compound I-05 and I-18 showed the highest activities at 600 mg/L against Mythimna separate,Helicoverpa armigera,Pyrausta nubilalis.I-05 and I-18 even showed 19.4%and 25.0%mortality at lmg/L against Helicoverpa armigera,which was similar to that of tenbufenozide(33.3%mortality).What's more,Helicoverpa armigera treated by compound I-05 and I-18 showed the same poison symptoms as tebufenozide.The results of molecular docking and molecular stimulation indicated that the binding modes of ?-05 and ?-18 are similar to that of tebufenozide forming the important hydrogen bonds and affinity to ecdysone receptor as they have similar binding average energy.In summary,the structure-activity relationship indicated 3-OCH3 and 4-C(CH3)3 in N-substituted phenyl ring were benefit for biological activity.3.Keeping 3-OCH3 and 4-C(CH3)3 on the phenyl ring,using ?-05 and ?-18 as lead,to further modify the bulks on the pyrazole ring and study the structure-activity relationship,Series ?containing 28 compounds were designed and synthesized.All the compounds ? exhibited certain insecticidal activities.Especially,several chemicals in Series ? showed 100%mortality at 600 mg/L against Mythimna separate,Helicoverpa armigera,Pyrausta nubilalis.Compounds ?-02 and ?-23 showed 60%mortality at 10 mg/L against Mythimna separate similar to tebufenozide.The result of molecular docking indicated that ?-02 and ?-23 showed important hydrogen bonds as their binding conformations were also similar to tebufenozide.Interestingly,the pyrazole ring of ?-23 has totally occupied the space in which tert-butyl of tebufenozide binded.Further molecular dynamic stimulation results predicted that with a similar binding free energy to tebufenozide,?-23 could be a potential ecdysone agonist while the bind target of ?-02 might not be EcR receptor as the value of binding free energy of ?-02 was much different from tebufenozide.In summary,increasing the hydrophobic effect and considering the suitable bulk effect on pyrazole ring will be beneficial to the inhibition activity to EcR.4.Keeping 3-OCH3 and 4-C(CH3)3 on the phenyl ring and considering the hindering effect(bulk effect)and hydrophobic effect of substituted pyrazole ring,Series ? containing 8 compounds were designed and synthesized through changing the tert-butyl on pyrazole of ?-05 and ?-18 into pyrazole ring closure.Most compounds of series ? showed 100%mortality against Mythimna separate,Helicoverpa armigera,Pyrausta nubilalis,Plutella xylostella at 600 mg/L and showed 100%mortality against Culex pipiens pallens at 10 mg/L.?-08 showed 40%mortality against Mythimna separate at 1 mg/L.Furthermore,those Helicoverpa armigera and Plutella xylostella treated by?-08 exhibited typical poison symptoms of ecdysone agonist.Molecular docking result showed that III-08 formed hydrogen bonds with important amino residues and the bicyclic pyrazole ring,offering relative high hydrophobic effect,has fully occupied the binding pocket in which the tert-butyl of tebufenozide binded.Further molecular dynamic stimulation results predicted that ?-08 is affinity to EcR receptor with similar binding free energy to tebufenozide.Above all,?-08 could be a potential high active ecdysone agonist.5.In order to study the structure-activity relationship,series IV containing 8 compounds were designed and synthesized using a strategy of changing the position of amide on the pyrazole ring of series ?.Most compounds of series IV showed lower activity against Mythimna separate,Helicoverpa armigera,Pyrausta nubilalis,Plutella xylostella than series ?,except IV-06 showed 100%mortality against Helicoverpa armigera,Pyrausta nubilalis,?-08 showed 86%mortality gainst Plutella xylostella at 600 mg/L and IV-04 showed 50%mortality at 0.25 mg/L against Culex pipiens pallens,which is higher than tebufenozide(1mg/L,60%mortality).Furthermore,poison symptoms and molecular docking results indicated that the target of these series may not be EcR receptor.6.In order to further study the structure-activity relationship,series V containing 25 compounds were designed and synthesized by taking ?-07 as lead compound,inserting methylene to increase the flexibility and replacing the phenyl ring with heterocyclic.Most compounds of series IV showed normal activity against Plutella xylostella.The result of primary bioassay against Plutella xylostella indicated that inserting the methylene between amide and phenyl ring or heterocyclic ring lead to the decreasing of insecticidal activities.However,replacing the phenyl ring with heterocyclic rings can improve the activity against Plutella xylostella.In summary,seven compounds(?-05,?-18,?-02,11-23,?-08,?-04 and ?-06)were found to have higher activity.The intereaction between these compounds and EcR was studied with molecular docking and dynamic stimulation method.Combined with the insect poison symptoms,compounds ?-05,1-18,?-23 and ?-08 were probably ecdysone analogs with different structure from Dibenzoylhydrazines and could be further developed for pests control.