Design,Synthesis And Antimicrobial Activity Evaluation Of Berberine Derivatives

Berberine（BBR）is one of the main bioactive secondary substances in a variety of medicinal plants such as rhizoma coptidis.It has many biological activities such as anti-tumor,anti-inflammatory,antimicrobial and anti-diabetes.At present,the chemical synthesis,structural modification and biological activity of berberine have been studied systematically at home and abroad.However,berberine as a natural precursor is limited by its poor physical and chemical properties or biological activity,which restricts its application in clinical or agricultural industry.Based on the previous work,this study aims to take berberine as the modification and optimization target,enhance its antimicrobial activity through derivative synthesis and structure optimization research,especially for the research and development of agricultural antimicrobial drugs,and develop a fungicide with high biological activity and excellent physical and chemical properties.In this study,by modifying the structure of berberine,a series of berberine derivatives with significant antimicrobial activity against agricultural pathogens were found,and the antimicrobial mechanism of the high active compounds against Botrytis cinerea was explored.The research content of this paper is composed of the following three parts:1.Design,synthesis and antimicrobial activity evaluation of C-13 modified berberine derivativesA total of 37 compounds were designed and synthesized by inserting different substituted benzyl groups into the C-13 position of berberine skeleton.In vitro antimicrobial activity tests showed that these compounds significantly improved the antimicrobial activity compared with berberine,especially against plant pathogens.These compounds showed a broad spectrum of antimicrobial activity.Compounds a-11,a-14,a-20,a-21,a-22,a-25 and a-26 showed better antimicrobial performance than other compounds.In particular,compound a-25 showed characteristics of broad spectrum and high antimicrobial activity,with EC₅₀value of 1.34μg/m L against Botrytis cinerea.2.Design,synthesis and antimicrobial activity evaluation of C-9 modified berberine derivatives based on the high active compoundsOn the basis of the above work,the derivatization and structural optimization of the high active compounds were carried out at C-9 position.After in vitro antimicrobial activity screening,it was found that compound e-6 had high inhibitory activity against Staphylococcus aureus and Candida albicans,with MIC₉₀ values of 0.39μg/m L and1.56μg/m L,respectively.3.A preliminary study of the mechanism of action of the high active compound a-25 on Botrytis cinereaBy analyzing the antimicrobial effect of compound a-25 on Botrytis cinerea from different angles,the most possible antimicrobial mechanism of compound a-25 was explored.Through the spore germination experiment,it was found that compound a-25could significantly inhibit the spore germination of Botrytis cinerea at low concentration,seriously affecting the expansion and reproduction of Botrytis cinerea.By observing the morphology of the mycelium treated with compound a-25,both the mycelium cell wall and the submicroscopic structure in the cell suffered varying degrees of damage,which seriously affected the growth and development of Botrytis cinerea and even led to the death of its cells.Further transcriptomics study revealed that compound a-25 may damage the mycelium membrane structure by affecting the metabolism of amino acids and sugars related to the membrane composition of Botrytis cinerea.By verifying the effect of compound a-25 on the cell membrane permeability of Botrytis cinerea,it was found that compound a-25 could cause serious damage to the cell membrane of Botrytis cinerea in a short time,leading to the leakage of a large number of contents in its cells.This study showed that compound a-25 affected the normal growth and development of mycelia mainly by destroying the structure of mycelium cell membrane,and thus played an antimicrobial role on Botrytis cinerea.