Synthesis Of Acetophenone Derivatives,Their Biological Activity And Mechanismstudy

Nature is a treasury of compounds.It has been providing us with natural products be of novel structures and diverse activities,from ancient times to the present.It is an important and main source of therapeutic or lead compounds for some diseases.Over half of all the small molecule drugs FDA-approved in 1981²014s were natural products or derived from natural products.In this work,the active molecule 2,4-dihydroxy-5-methylacetophenone,which isolated from the fermentation broth of Polyporus picipes Fr,was used as a template.Based on this structural template,the basis of previous research and known structure–activity relationship of the research group,106 derivatives were designed and synthesized by means of pharmacophore splicing technology.The structure of the two series of derivatives were confirmed by NMR and MS methods.The in vitro,in vivo and theoretical calculations were carried out to systematically screen the compounds against phytopathogenic fungi,pathogenic bacteria and?-glucosidase inhibitory activity and proposed a structure-activity relationship.Four potential active lead compounds were obtained in the full text,and the mechanism of action was studied.The main results were found as follows:1.Forty-one acetophenone analogues were designed and synthesized.The inhibitory activities of fifty-three acetophenone molecules including twelve acetophenone substrates against seven plant pathogenic fungi were evaluated,and the SAR was proposed.Eight potential lead compounds 2-5a,2-5b,2-5c,2-5d,2-5e,2-5f,2-6d and 2-7b showed better inhibitory activities against different phytopathogenic fungi and good“drug-like”properties.Among the test compounds,compound 2-5d displayed the best inhibitory activity against C.sp.(IC₅₀=6.0?g/mL),which was superior to two commercial drugs,thiophanate-methyl(IC₅₀=23.3?g/mL)and carbendazim(IC₅₀>50?g/mL).Moreover,2-5d maintained its good inhibitory activity against C.sp.and B.cinerea in vivo,the inhibition rates were 73.1%and55.3%,respectively.The results further confirm the potential of such compounds to develop as agricultural fungicides.2.Sixty-four bromoacetophenone derivatives were designed and synthesized.The inhibitory activities of these derivatives against five plant pathogenic fungi were evaluated and the SAR was proposed.Eight potential lead compounds 3-1,3-3,3-5,3-7,3-11a,3-11k,3-12 and 3-13 showed better inhibitory activities against different phytopathogenic fungi.To investigate the active mechanism of 3-13,C.gloeosporioides was used as the tested pathogen,the effect of some physiological biochemical indexes,such as the growth mass,soluble protein content,MDA content,ROS content,and the metabolic enzyme?including CAT,SOD,ATPase,SDH and LDH?activities of the pathogen were examined.The results showed that the inhibitory effect of 3-13 against C.gloeosporioides was concentration-dependent.By inhibiting the activity of CAT and SOD,3-13 could result in the accumulation of MDA and ROS in the cells,then decreased the ability of C.gloeosporioides to scavenge membrane lipid peroxidation and oxygen free radicals.Meanwhile,3-13 also inhibited the activity of SDH,ATPase and LDH in C.gloeosporioides,preventing the normal metabolic pathways such as the TCA and glycolysis,thereby exerting its inhibitory effect on the growth of the pathogen.In addition,3-13 showed low side effects on seed germination and cytotoxicity tests and showed good“drug-like”properties,which further confirmed the development and application value of such compounds.3.The antibacterial activity of the synthetic bromoacetophenone derivatives and their template compound 1-94 against six pathogenic bacteria was evaluated,and the SAR was proposed.Among them,compound 3-5 showed the best antibacterial activity,was further studied on its activity mechanism against R.solanacearum?MIC=12.5?M?.The mechanism of antibacterial action was further studied by SEM,TEM,growth curve,cell surface hydrophobicity test and cell membrane permeability test,which indicated that 3-5 could exert its bactericidal effect by damaging bacterial cell membranes and increasing membrane permeability.It is worth mentioning that compound 3-5 not only exhibited low cytotoxicity,good thermal stability and good“drug-like”properties,but also showed good protective efficacy of 62.5%inhibition rate against R.solanacearum in the antibacterial assay in vivo.These results further demonstrated the potential of the compound 3-5 to develop into a novel agricultural bactericide.4.The synthetic bromoacetophenone derivatives and their template 1-94 were evaluated for their?-glucosidase inhibition,and the SAR was proposed.Eight compounds 3-14e,3-14j,3-14p,3-14q,3-14x³-14z and 3-14ac showed better inhibitory activity with IC₅₀ values ranging from 1.68 to 7.88?M.Among all tested compounds,3-14z was found to be the most efficient(IC₅₀=1.68?M),being 32.6-fold and 13.5-fold more active than acarbose(IC₅₀=54.74?M)and genistein(IC₅₀=22.64?M),respectively.The inhibition kinetics and binding mechanism of 3-14z against?-glucosidase were studied by means of fluorescence spectroscopy,CD spectroscopy,ITC and molecular docking.The results showed that compound 3-14z induced the fluorescence quenching and conformational changes of the enzyme,by forming an?-glucosidase-3-14z complex in a mixed inhibition type?K_i=2.28?M?.3-14z bound with?-glucosidase with one affinity binding site,via an enthalpy-driven spontaneous exothermic reaction.The synchronous fluorescence and CD spectra also indicated that 3-14z encouraged the enzyme conformation changing,the molecular docking results visually presented this combination pattern.In addition,the in vivo experiments showed that compound 3-14z also had good inhibitory activity against?-glucosidase on intestinal mucosa,which significantly attenuated postprandial blood glucose levels.At the same time,compound 3-14z also has good pharmacokinetic properties and low cytotoxicity,which indicating the potential of compound 3-14z to develop into a novel?-glucosidase inhibitor.In summary,this work systematically studied the antifungal,antibacterial and?-glucosidase inhibitory activities of two series of 106 acetophenone derivatives,which greatly enriched the activity diversity of these compounds.The effectiveness of in vivo experiments and mechanism study in this paper not only enriched the candidate drug types,but also provided theoretical basis and support for drug development based on active acetophenone skeleton.