Study On Inhibition Of Components In Garlic Extracts For Pathogens And Its Mechanism

Effeective organic solvents extracting garlic(Allium sativum L.) were screened in the paper. Then in vitro and in vivo effect of garlic extract on several important pathogens in vegetables such as cucumber scab(Botrytis cinerea),Cucumber gray mold(Cladosporium cucumerinum) and so on were tested systematically. After analysis and purification of inhibitory components in garlic extract, the paper discussed the mechanism of its interaction with pathogens. They included the target binding situation of inhibitory components in fungi, its effect on enzymes catalysis,proteins and DNA product.Ethyl acetate could harvest garlic extract more efficient than other organic solvents. Diluted to 0.1μL/mL, garlic ethyl acetate extract (EAE) exhibited high inhibitory effect on spores germination and hyphae growth of vegetables pathogens. At concentration of 0.1μL/mL, cucumber scab(Botrytis cinerea),cucumber gray mold(Cladosporium cucumerinum), cucumber powdery mildew(Erysiphe cucurbitacearum) and cucumber downy mildew(Pseudoperonospora cubensis)could be controlled. The inhibition was stable in acid conditon, but in neutral and alkaline condition(pH value beyond 7.0) or in high temperature(beyond 90℃), the action decreased greatly. Analysing the components in garlic by thin layer chromatography and purifying them by silica column chromatography, the main active compounds was obtained,whose Rf is 0.41～0.42.0.005g/mL L-cysteine solution had anti-inhibition action in experi-ments, which showed that the active components shot the situation containing –SH in pathogens. When it happened, the catalysis of protease and the cellulase were inhibited. Also the produce of proteins and DNAs was inhibited because 0.025μL/mL garlic extract could decrease the contains of proteins and DNA separately at rate of 49.3% and 81.6%.Based on the study , garlic can be developed as an plant-derived fungicides.