Antimicrobial Activity And Mechanism Of Citral And Derivatives

In order to screen high-effective medicine with antifungal activity against Rhizocotonia solani,Colletotrichum gloeosporioides,Fusarium oxysporum,and Pyricularia grisea 4 common plant pathogen,the antifungal activities of citral and derivatives（15 kinds of compounds）from were investigated against Rhizocotonia solani,Colletotrichum gloeosporioides,Fusarium oxysporum,and Pyricularia grisea4 common plant pathogen by mycelium growth rate.The results showed that the 15kinds of the compounds exhibited certain fungicidal activity,and with the increasing concentration,fungicidal activity became stronger.Natural citral,Natural citronella,Neroli Su,B bit ionone demonstrates the most powerful antifungal activity against Rhizocotonia solani,and the EC50 values of them is 18.4160,16.1051,23.3223,23.3424 mg/L.Among 15 kinds of the compounds,the most powerful the compounds against Colletotrichum gloeosporioides,Fusarium oxysporum,Niveum,and Pyricularia grisea were respectively Natural citronella,B bit ionone,Lemonile,and Irone.And their EC₅₀ values were 16.11,31.53,37.64,and 133.60 mg/L.The cell membrane of relative permeability of Colletotrichum gloeosporioides,Pyricularia grisea increased,and the cell membrane of Colletotrichum gloeosporioides,Pyricularia grisea was damaged by B bit ionone,Lemonile.The cell membrane of relative permeability of Fusarium oxysporum f.sp.Niveum didn‘t increases,and the cell membrane of Fusarium oxysporum f.sp.Niveum wasn‘t damaged by Irone.The antifungal activity of citral and derivatives from Litsea cubeba against Poria placenta（Fr.）Cooke,Trichoderma viride,and Coriolus versicolor three wood fungi were investigated by mycelium growth rate.The results showed that the ten kinds of the compounds exhibited certain fungicidal activity,and with the increasing concentration,fungicidal activity became stronger.The inhibitive effects of the ten the compounds on the three wood fungi were respectively analyzed in comparison with the effect of triadimefon and the results showed the most powerful the compounds against Poria placenta（Fr.）Cooke,Trichoderma viride,and Coriolus versicolor were respectively Citral acetal 1,2-propanediol,B bit ionone,and Irone.And their EC₅₀values were 18.69,23.50,and 32.21 mg/L.The cell membranes of Poria placenta（Fr.）Cooke,Trichoderma viride and Coriolus versicolor were damaged by Citral acetal1,2-propanediol,B bit ionone,and Irone.The antimicrobial activity of 11 kinds of the compounds of citral and their derivatives on E.coli,Staph.aureus,Staph.epidermidis,P.areuginosa by the inhibition zone experiment and the minium inhibititory concentration（MIC）experiment.The results showed that antimicrobial activities of 11 kinds of natural the compounds and their derivatives against E.coli,Staph.aureus,Staph.epidermidis,P.areuginosa were different.The MIC on test organisms were as follows:Hydroxy citronellal had strong antimicrobial activity against E.coli,the MIC was 8 mg/L,and Natural citronella had strong antimicrobial activity against Staph.aureus,the MIC was 16mg/L,and Citral acetal 1,2-propanediol had strong antimicrobial activity against Staph.epidermidis,the MIC was 8 mg/L,and Natural citronella had strong antimicrobial activity against P.areuginosa,the MIC was 8 mg/L.The cell membrane of E.coli was damaged by Hydroxy citronellal,and the cell membrane of P.areuginosa by Natural citronella.The antifungal activity of 15 kinds of citral and their derivatives was investigated against Rhizocotonia solani by mycelium growth rate.Cultured Rhizocotonia solani in Marcus modified medium,it produces cellulose degrading enzymes（CX）,poly-galacturonic acid enzyme（PG）,pectin methyl galacturonic acid enzyme（PMG）,poly-galacturonic acid transferase enzyme eliminate（PGTE）,and pectin elimination of methyl transferase enzyme（PMTE）,handled Rhizocotonia solani cell by Natural citral,Natural citronella,Neroli Su,B bit ionone,compared w ith the blank control,the inhibition rate against enzymatic activities of CX,PG,PGE,PGTE,and PMTE were 52.98%,57.61%,46.92%,82.85%and 87.94%respectively at the concentration of EC₅₀ of natural citral;the inhibition rate against enzymatic activities of PGTE and PMTE,were all above 90%respectively at the concentration of EC₅₀ of natural citronella;the inhibition rate against enzymatic activities of CX,PG,PGTE and PMTE,were 60.91%,39.11%,25.35%,and 58.08%respectively at the concentration of EC₅₀ of Neroli Su;the inhibition rate against enzymatic activities of PG,PGE,PGTE and PMTE,were 18.68%,66.67%,18.61%,and 67.22%respectively at the concentration of EC₅₀ of B bit ionone.Cultured Rhizocotonia solani in Czapek–Dox（CAT）medium,compared w ith the blank control,it produces Cata-lase,the inhibition rate against enzymatic activities of CAT is 38.07 at the concentration of EC₅₀ of Neroli Su,the inhibition rate against enzymatic activities of CAT is 8.38 at the concentration of EC₅₀ of B bit ionone;it produces Peroxidase（POD）,the growth rate against enzymatic activities of POD is 48.72 at the concentration of EC₅₀ of Neroli Su,the growth rate against enzymatic activities of POD is 25.18 at the concentration of EC₅₀ of B bit ionone;it produces Superoxide Dismutase（SOD）,the inhibition rate against enzymatic activities of SOD is 63.48 at the concentration of EC₅₀ of Natural citral,the inhibition rate against enzymatic activities of SOD is 17.96 at the concentration of EC₅₀ of B bit ionone;it proude Malondialdehyde（MAD）,the amount of MDA respectively increases at the concentration of EC₅₀ of Natural citral and Natural citronella.The cell membranes of Rhizocotonia solani were damaged by Natural citral and Neroli Su.Rhizoctonia solani grows on PDA,its colony color,color sclerotia,sclerotia distribution,sclerotia dry weight presents differences by the impact of Natural citral,Natural citronella,Neroli Su,B bit ionone,in which natural citronella make Rhizoctonia sclerotia dry weight gained weight 0.35g;the treatment time of Sclerotia by Natural citral,Natural citronella,Neroli Su,B bit ionone was become longer,the germination and diameter of sclerotia was become smaller.Rhizoctonia sclerotia a pathogen of rice sheath blight,could produce a toxin.The similar symptom appeared on the rice leaf inoculated with either toxin or pathogen,The toxin was extracted and purified by centrifugalization,sterilization and absorption chromatography through active carbon column with methanol as eluant.The results from biological activity assay suggested that the toxin could inhibit obviously the growth of rice radicle,plumule of different rice seeds.