Study On Molluscicides Design Based On Target Protein PcAdv,PcnWAS And PcRoo In Pomacea Canaliculata

Pomacea canaculate does great harm to crop production,ecological environment and human health,and currently,chemical molluscicides are the main method to control P.canaculata.However,common molluscicides such as tetraacetaldehyde and chlornitrothiamine can not control it effectivelly.To find new compounds with molluscicidal activity for the prevention of P.canaculata,in this study,with the help of computer-aided drug design,protein Advlin（PcAdv）,neural Wiscott-Aldrich syndrome isoform X1（PcnWAS）and ciliated root-like（PcRoo）were set as targets,a series of compounds with different degrees of molluscicidal activities were obtained,and then a model could reflect the relationship between their structure and molluscicidal activity was established.Finally,the efficient and reasonable screening of molluscicidal compounds was realized.This study provided a technical scheme for the screening,development and directional design of new molluscicides,and the main results are shown as follows:1.The models of target protein PcAdv,PcnWAS,and PcRoo,as well as their binding sites with probe compounds,were predicted through computational.Five models were constructed for different target proteins,and the most reasonable model with the lowest energy and the most reasonable arrangement of amino acid twist angles were selected.On this basis,cavity method was used to find the binding region between the probe compound and target proteins.The results showed that there were5 and 3 regions with strong binding ability between pedunsaponin A and protein PcAdv and PcnWAS respectively,and 2 regions with strong binding ability between arecoline and PcRoo.Results of molecular docking indicate that the binding sites between the target protein and probe compounds pedunsaponin A and arecoline are549-ser,585-lys,112-ala,and 47-ser respectively.2.A virtual screening in database Drug Bank with 9213 candidate compounds was conducted via molecular docking techniques.The rigid docking results showed that 15 compounds were screened for the target proteins PcAdv,PcnWAS,and PcRoo respectively that ranking high.Based on the results of rigid docking screening,flexible docking was carried out,and 6 compounds with significantly reduced binding energy were selected,including 6-adenosine tetraphosphate methyl-7,8-dihydropterin,3,8-diamino-6-phenyl-5-[6-[1-[2-[（1,2,3,4-tetrahydro-9-aridinyl）amino]ethyl]-1,1,3-triazole]hexyl]-phenanthridine,potassium alginate,thiocoenzyme adenine dinucleotide,baclofen and acedoben.3.Several new molluscicidal compounds including potassium alginate,thiocoenzyme adenine dinucleotide and baclofen were obtained through indoor bioassay.The killing effects and symptoms of hit compounds on the snails were studied by immersion method,Winkler iodometry,sodium hypobromate oxidation method,ultraviolet absorption method and paraffin section method respectively.After that the target of these compounds on P.canaculata were verified.The results showed that the LC₅₀values of thiocoenzyme adenine dinucleotide and baclofen killing P.canaculata were 16.2437 mg/L and 57.7102 mg/L,respectively.At the same time,these compounds could cause similar poisoning symptoms in P.canaculata,which were manifested as abnormal excretion,alteration of metabolic pathway,decreased content of hemocyanin,gill cilia shedding and decrease of target genen expression.Further,isothermal titration calorimetry was used to study the binding of candidate compounds and target proteins.The results showed that the target proteins and candidate compounds were bound in vitro,their binding constents with PcnWAS were2.17±0.51×10^-4/M and 2.08±0.94×10^-4/M.4.Setting pedunsaponin A as a template,pharmacophore models and 3D-QSAR models were established to reflect the structure and activity of molluscicidal compounds.The construction results of the pharmacophore model indicate that the model contains four chemical characteristic elements,namely,2 hydrophobic interaction groups and 2 hydrogen bond receptor groups,and the pharmacophore characteristic elements of the compound have a certain geometric constraint relationship with molluscicidal activity.The distance ratio between the hydrophobic interaction group and the two hydrogen bond donor groups and the two hydrogen bond receptors is 13.624:10.516:5.895.The results of 3D-QSAR showed that there was a high correlation between the structure and molluscicidal activity of pedunsaponin A and other pentacyclic triterpenes.By optimizing the template compound pedunsaponin A,compounds with higher activity could be obtained.By changing the three-dimensional field,electrostatic field,hydrophobic field,hydrogen bond donor field,and hydrogen bond acceptor field,three novel compound structures with snail killing potential were designed.Molecular docking results showed that the binding energies of these compounds after binding to target proteins were significantly reduced.All these results indicated that,based on the structure of target protein PcAdv,PcnWAS and PcRoo,new molluscicidal compouds could be found via computer-aided-pesticide-design technology,and this study lay a foundation of new molluscicides design.