Antimicrobial Activity Of Secondary Substances From Walnut Seedcases

In this paper, the antibacterial activity, extraction technology, active ingredient and antimicrobial mechanism of secondary from walnut seedcases were studied. The results were shown as follow:(1) Antibacterial activity of the extract from walnut seedcases was studied. The results showed that the ethanol extracts of walnut seedcases have different range activity to tested fungus. The inhabitation of acetyl acetate extract is the best when the concentration of every extract phase is 40 mg·mL^-1. The inhabiting rate of the extract is 100% to Botrytis Cinerea Pers, Thanatephorus cucumeris and Rhizoctonia cereal. Diameter of the inhabited ring is 12.07mm and 12.54mm to Bacillus subtilis and Staphylococus aureus Rosenbach, respectively. Different concentrations have different antifungal activities to the same pathogenic fungus. Their EC50 values of acetyl acetate's extraction against mycelia growth of Botrytis Cinerea Pers, Thanatephorus cucumeris, Glomerella cingnlata.schr.et, Rhizoctonia cereal and Fusarium graminearum are 7.2634,6.2191,9.0695,5.5912 and 10.3102 mg·mL^-1, respectively. The results of pot experiment showed that the protective and effects of ethyl acetate extract against the Erysiphe graminis was 71.42%, and the therapeutic effects was 68.96%.(2) The active substance of seedcases was extracted by different solvents and methods, and its antibacterial activity was determined. Guiding the inhibition rate of extract is to Thanatephorus cucumeris, Glomerella cingnlata.schr.et, the condition for extracting activity of antibacterial substances from walnut seedcases was optimized by orthogonal experiment. The antibacterial activity of extracts of different solvents and methods from walnut seedcases was determined. The results showed that the extracts with different solvent and method have different antifungal activities to the same pathogenic fungus. When concentration inoculated is 1g·mL^-1, antibacterial activity of the extract with 95% ethanol is the best. The successive order of factors affecting the extracting was ethanol concentration, extract times, extracting time and liquid-solid ratio. So the method is cold soak, the optima conditions is that 85% alcohol cold soaks in 28h for fifth and liquid-solid ratio is 5:1。(3)Active tracking method is adopted to isolate antiviral antibacterial substances from Walnut seedcases. The oilⅠ, compound A & B was obtained from extraction of ethyl acetate through column chromatography. The chemical compositions of oilⅠwas analyzed by GC-MS. The results showed that the main components of oilⅠis 2, 6, 10, 14-tetramethyl- Hexadecane and D-Allose. By the spectrum data, we can get the Chemical Structure of compound A & B is 4,8-dihydroxy-3,4-dihydronaphthalen-1(2H)-one andβ-sitosterol. Their EC50 values of compound A and B to Thanatephorus cucumeris, Glomerella cingnlata.schr.e are 0.4589 & 0.4707,0.6337 & 36.8933 mg·mL^-1.(4) The antimicrobial mechanism of compound A was studied. The results showed that compound A can make fungal clustering, and the hyphae were breaking after treated by compound A. In addition, compound A can effectively shorten the growth cycle of E. coli.