Synthesis,Anti-tumor Activity And Mechanism Of 1-(4-Substituted Phenyl)-2-Ethyl Imidazole Derivatives

Background:Imidazole is an important part of histidine and histamine in organisms.Imidazole plays a major role in biological activity and physiological functions.Due to the special structure of the imidazole ring,derivatives containing imidazole structure have great potential for development.Such as anti-cancer,anti-inflammatory,anti-bacterial and anti-oxidation and other biological activities.Previous studies in our laboratory showed that compound I containing imidazole structure had weak anti-tumor activity in vitro(IC₅₀=300-500μM).However,the compound II obtained by opening the upper ring of the imidazole ring is slightly more active against lung cancer and liver cancer cells(IC₅₀=100-300μM).We speculate that its flexible structure leads to this difference in anti-tumor activity,and has the ability to act as a precursor drug.Objective and significance:In this study,compound II was used as the lead compound.compound II several structurally modified imidazole derivatives were designed and synthesized by replacing substituents,in order to screen out the structure of compounds that can inhibit tumor cell proliferation and have low toxic and side effects.Explore the inhibitory effect of1-（4-substituted phenyl）-2-ethylimidazole derivatives on the proliferation and apoptosis of tumor cancer cells,expecting to be applied in clinical,for the benefit of cancer patients.Methods:Nineteen 1-（4-substituted phenyl）-2-ethylimidazole derivatives were synthesized from 2-ethylimidazole and p-fluoronitrobenzene through substitution,reduction and condensation reaction.The anti-tumor activity and mechanism of action were studied by MTT method,Hoechst/PI cell apoptosis staining method and western blotting.Results:Through synthesis,19 target compounds were obtained and identified by¹H-NMR,¹³C-NMR and HRMS.Most of the tested compounds showed significant anti-tumor activity.Among them,the inhibitory activities of compounds 4e-4i,4l,4m,4q are better than the positive control 5-FU and MTX and compound 4f has the best inhibitory activity against A549,He La,SGC-7901 with IC₅₀values of 6.60,3.24 and 5.37μM.Moreover,compound 4f showed lower toxicity against normal hepatocytes L-02(IC₅₀=152μM).Observed under a fluorescence microscope,as the time of drug action increases,the cells change from their original full,brightand adherent growth state to shrunken and fuzzy suspension growth.Compound 4f induced cell apoptosis rate was better than 5-FU.Western blot detection results showed that compound 4f up-regulated the expression of pro-apoptotic proteins Bax,Caspase-3,and PARP,and down-regulated the expression of anti-apoptotic protein Bcl-2.Conclusion:1.Nineteen novel 1-（4-substituted phenyl）-2-ethyl imidazole derivatives 4a-4s were synthesized from 2-ethylimidazole by substitution,reduction and condensation reactions.2.Compounds 4c,4e-4i,4l,4m and 4q have good inhibitory activity against three cancer cell lines（A549,SGC-7901 and He La）,of which compound 4f has the best inhibitory activity against A549,He La and SGC-7901.The IC₅₀values are 6.60,3.24,and 5.37μM,respectively.3.Compound 4f induced apoptosis of tumor cells（A549,SGC-7901 and He La）by up-regulating the expressions of pro-apoptotic proteins Bax,Caspase-3,PARP and down-regulating the expression of anti-apoptotic protein Bcl-2.