Design And Synthesis Of Novel Neuraminidase Inhibitors Based On Privileged Structures Hydrazone And Acylhydrazone

According to ligand-based rational drug design principle,privileged structure hydrazine and acylhydrazone containing various pharmacological activities were introduced via pharmacophores,scaffold hopping,and bioelectronic isostere principle.In order to develop novel,efficient and safe anti-influenza drugs,147 compounds with novel molecule scaffold were designed,synthesized and evaluated their influenza virus NA inhibitory activities.And their structure-activity relationships were discussed.Molecular docking was used to simulate the interaction model between high activity compounds and NA active sites.（1）Generation of common features pharmacophore model and design of the target compoundsAnalysis of natural product-based NA inhibitors revealed that their molecule scaffold consists of two aromatic ring systems and one linking fragment.And a pharmacophore model of natural product-based NA inhibitors was generated.Containing two hydrogen bond acceptors and one hydrogen bond donor is the main feature of the pharmacophore model.Based on the characteristics of the pharmacophore model and the molecule scaffold,the aromatic hydrazone derivatives A,aromatic acylhydrazone derivatives B and aromatic bis（acylhydrazone）derivatives C with novel molecular skeletons were designed by the principle of scaffold hopping and bioisosterism,replacing the linking fragments with the privileged structure hydrazone and acylhydrazone,and optimization of hydrogen bond receptors and donors.（2）Synthesis of aromatic hydrazone derivatives and chalcone derivativesFormamide,diethyl malonate,2-chloro-5-trifluoromethylpyridine,2-chloro-3-nitro-pyridine,2-chloro-5-nitropyridine,3,6-dichloropyridazine and 2,4-dinitrophenylhydrazine as starting materials,the 2,4-dinitrophenyl aromatic hydrazone derivatives A1^A5,pyridine aromatic hydrazone derivatives A6^A22,pyridazine aromatic hydrazone derivatives A23^A29,pyrimidine aromatic hydrazone derivatives A30^A51,pyrimidine bis（hydrazone）derivatives A52^A57,and chalcone derivatives Y1 and Y2 were obtained in good synthesis yield via a simple and efficient synthetic route.And the synthesis methods of the intermediate4,6-dichloro-pyrimidine,4-chloro-6-aminopyrimidine,and 3-chloro-6-hydroxypyridazine were optimized.（3）Synthesis of aromatic acylhydrazone derivativesUsing a simple and efficient synthetic route,benzoic acid derivatives or methyl benzoate derivatives were used as starting materials,and the corresponding intermediates were synthesized by an esterification reaction and then reacted with hydrazine hydrate.The aromatic acylhydrazone derivatives B1^B57 were prepared by the dehydration condensation reaction in good yield.（4）Synthesis of aromatic bis（acylhydrazone）derivativesDimethyl terephthalate,dimethyl isophthalate,diethyl pyridine-3,5-dicarboxylate,dimethyl carbonate,diethyl oxalate,and diethyl malonate were used as starting materials.The corresponding terephthaloyl bis（acylhydrazone）derivatives C1^C4,isophthalic bis（acyl-hydrazone）derivatives C5^C20,3,5-pyridinedicarboxylic acid bis（acylhydrazone）derivatives C21^C24,carbonic acid bis（acylhydrazone）derivatives C25^C28,oxalic acid and malonic acid bis（acylhydrazone）derivatives C29^C33 were obtained by a simple and efficient synthesis route in good yield.（5）Neuraminidase inhibitory activities and structure-activity relationshipsIn order to discover a lead compound having stronger NA inhibitory activity,147 target compounds designed and synthesized were evaluated for influenza virus NA inhibitory activities and their structure-activity relationships were investigated.The test results showed that 11 of the 57 aromatic hydrazone derivatives A had better NA inhibitory activity than the chalcone derivative Y2,and the four compounds had a good level of inhibitory activity against NA,and 49%of the compounds reached the moderate and above levels,in which compound A52(IC₅₀=24.20±3.30μmol/L)showed the strongest in vitro NA inhibitory activity.18 of the 57 aromatic acylhydrazone derivatives B had better NA inhibitory activity than the chalcone derivative Y2,and the ten compounds had a good level of inhibitory activity against NA,60%of the compounds reached the moderate and above levels,in which compounds B29 and B31 showed the stronger NA inhibitory activities,IC₅₀ values were23.37±0.78 and 23.89±4.33μmol/L,respectively.27 of the 33 aromatic bis（acylhydrazone）derivatives C had better NA inhibitory activity than the chalcone derivative Y2,and the twenty three compounds had a good inhibitory activity against NA,and 94%of the compounds reached moderate and above levels,in which compounds C4,C19,and C29showed the strongest NA inhibitory activity with IC₅₀0 values of 20.72±2.00,20.78±2.98and 20.81±3.00μmol/L,respectively.Lipinski’s rule and chemo-informatics properties analysis exposed that most of synthetic target compounds may be potential oral active drug candidates.Molecular docking depicted that compounds A52,B29,and C4 showed a good binding conformation interacting with the NA active site with good binding energies of-7.49,-5.84 and-9.09 kcal/mol,respectively.The structure-activity relationships analysis showed that the aromatic bis（acylhydrazone）molecule scaffold is superior to the aromatic hydrazone and aromatic acylhydrazone molecule scaffold,and the 3,5-pyridinedicarboxylic acid bis（acylhydrazone）molecule scaffold is the most excellent aromatic bis（acylhydrazone）molecule scaffold.Moreover,the introduction of an active pharmacophore which can act as a hydrogen bond donor or a hydrogen bond acceptor on the molecular skeleton contributes to an increase in the NA inhibitory activity.