Study On Antimicrobial Mechanism And Antioxidant Activity Of Chitosan-Polyphenols

In order to study the antimicrobial and antioxidant activity and mechanism of chitosan-polyphenols,the antimicrobial activity of chitosan-polyphenols was studied by inhibition zone method,and the antimicrobial mechanism of chitosan-polyphenols was analyzed by transcriptome differential expression.The antioxidant activity of chitosan-polyphenols was detected by total reduction force,ABTS free radical clearance rate and DPHH free radical clearance rate.1.The results of antimicrobial activity showed that IC₅₀of chitosan-tannic acid against Colletotrchum musae,Fusarium lateritium Nees and Bipolaris cactivora was 0.62 mg/m L,0.65 mg/m L and 0.65mg/m L respectively.The IC₅₀of chitosan-gallic acid against Colletotrchum musae,Fusarium lateritium Nees and Bipolaris cactivora was 0.60 mg/m L,0.66 mg/m L and 0.78 mg/m L respectively.Chitosan-gallic acid had the smallest IC₅₀value and the strongest antimicrobial activity against Colletotrchum musae.2.There were 2868 differentially expressed genes in Colletotrchum musae after treatment with chitosan-gallic acid.Chitosan-gallic acid regulated the differential expression of multiple related genes of Colletotrchum musae,achieving multi-target antimicrobial activity.Chitosan-gallic acid reduced the antioxidant capacity of Colletotrchum musae by inhibition of peroxisomes,laccase activity and catalase activity.Chitosan-gallic acid also damaged cell membranes of Colletotrchum musae by regulating cell membrane lipid signaling pathways and affecting fatty acid metabolism.Moreover,chitosan-gallic acid reduced the expression of ABCC1 transporter and extracellular signal-regulated protein kinase（ERK1/2）,reduced the drug resistance of Colletotrchum musae.In summary,there were multiple targets for chitosan-gallic acid against Colletotrchum musae.3.The antioxidant activity of chitosan-polyphenols showed that the IC₅₀of chitosan-gallic acid and chitosan-tannic acid in removing DPPH free radicals were 0.25 mg/m L and 0.30 mg/m L.Respectively,they were lower than that of VC（0.50 mg/m L）.It showed that the antioxidant activity of chitosan-polyphenols（gallic acid,tannic acid）was higher than that of VC.