| Glycoalkaloid extracted from potato skins with5%sulfuric acid soaking extracting and precipitated with28%ammonia,then column chromatography and thin-layer chromatography was used to purify and separate to get a-solanine.a-Solanine was selected for the test material,and botrytis cinerea was conducted to the strain,the spread plate was using to research the minimal inhibitory concentration(MIC) and the minimal fugicide concentration(MFC) of a-solanine against botrytis cinerea,and mycelial growth rate method was used to measure the inhibition rate and median effective concentration(EC5o).Oxford cup method was using to study the influence factors,such as pH,heat treatment and metal salt,on this basis,antibacterial mechanism of a-solanine against botrytis cinerea were preliminary studied.The result were shown as below:1. The glycoalkaloid was extracted from the potato skins with5%sulfuric acid soaking extracting and precipitated with28%ammonia, quality of coarse sample is1.38mg/g,silica gel was as adsorbent, a-solanine monomer was gotten from elution part of ethyl acetate-95%ethanol-10%ammonia(80:30:4,v/v) by thin-layer chromatography,the developing solvent is the chloroform-methanol-2%ammonia (70:30:5, v/v),the Rf of a-solanine is0.38that is same of standard. The eluant was rotary and evaporated to get the a-solanine.2. Spread plate was used to determine the minimal inhibitory concentration and the minimal fugicide concentration of a-solanine against botrytis cinerea,it showed that they were respectively12.5μmol/L and18.75μmol/L.By the mycelial growth rate method, the inhibition rate and median effective concentration were measured,the results were that the inhibition rate was93.24%when the concentration of a-solanine were18.75μmol/L and ECso was7.241μmol/L.3. Antimicrobial activities of a-solanine with different concentrations against gray botrytis cinerea in vitro by the Oxford cup method,the result show that have high sensitivity when the concentration of a-solanine is50μmol/L,and sensitivity will increase with the increasing of concentration of a-solanine.So the experiment choose50μmol/L as the optimal concentration,and in this concentration,the experiment studied bacteriostatic activity of a-solanine influenced by the pH,the temperature and times of heat treatment,metal salt.Its inhibition effect on botrytis cinerea was best when pH value was seven; The inhibition effect would be influenced by heat treatment,and it was stable when the temperature was lower than80℃, especially when the temperature was lower than60℃,the change of diameter was smaller than one millimeter,along with the extension of heating time;when the temperature is higher than80℃,the diameter would be decrease with the increasing of temperature and the extension of heating time;The bacteriostatic effect would be strengthened when α-solanine combined NaCI, KC1, CaCh and MgSO4,their concentration were0.25%,0.5%,1%,2%and3%.Between this concentration of0.25%and3%,the bacteriostatic diameter would be largen and antibacterial effect would ba better with the increase of concentration.4. The transfer test showed that the way of α-solanine against botrytis cinerea was related to its concentration and action time, α-solanine whose concentrations were6.25μmol/L and12.5μmol/L had restraining effect when it contacted3days with botrytis cinerea;It all had lethal effect that α-solanine whose concentrations were6.25μmol/L and12.5μmol/L contacted6days and12days or α-solanine whose concentrations were18.75μmol/L contacted3days,6days and12days; Experiments od the time of the botrytis cinerea spores killed came to a conclusion that the death time of botrytis cinerea spores with the treatment of18.75μmol/L and25μmol/L α-solanine were10hours and8hours.Botrytis cinerea spores were killed effectively by α-solanine which concentration was more than25μmol/L.The extracellular infiltration rate of cell of botrytis cinerea increased,and botrytis cinerea was cultivated in the PDB medium that had different concentration of α-solanine. |
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