Antifungal Effect Of Euphorbia Humifusa Wild.'s Extract Against Sphaerotheca Fuligenea And Active Substance Isolation And Purification

In vitro test showed that the Euphorbia humifusa Wild.'s extract had an inhibition effect against Sphaerotheca fuligenea,The inhibition rate was 100% when extract concentration was 20mg/mL and the inhibition rate got to 67.66% even at the concentration of 2.5mg/mL. The extract of E. humifusa had different preventive effects against four strains of S. fuliginea from four districts in Shanghai. The preventive effects on the Qibao and Baoshan were better than those of Nanhui and Qingpu. The microorganism inhibition experiment by filter papers indicated that the extract of E. humifusa had higher inhibition effect against bacteria than on pathogenic fungus. Diameters of the zone of inhibition of salmonellas, Echerichia coli and Staphylococcus aureus were 15.77mm, 12.27mm and 10.53mm respectively. The extract of E. humifusa had a certain effect against Colletotrichum lagenarium, Botrytis cinerea, Rhizoctomia solan and Pyricularia oryza but no effect against Helminthosporium maydis and Gibberella zea.The 4 cation exchange resins and ethanol deposition were used to isolate the active fractions from supernate after alkali deposition. The results showed that all of the cation exchange resins weren't good enough to separate the active fractions completely, but the great mass of impurity could be separated from water extract by ethanol deposition method and the high efficient active fraction was in the supernate which protective effect was 83.51%, higher than the protective effect of supernate after alkali deposition. The better separation system of isopropanol: ammonia: water=8:1:1 was obtained with thinner-layer chromatography (TLC). With this separation system, the supernate after ethanol deposition was chromatographed over a column of silica gel and preparation TLC. We got the active fraction 4 against S. fuliginea,which protection effect was 83.08%. The active fraction 4 had two peaks by LC-MS analysis and their molecular weights might were 401 and 781 respectively.From the results above, we can see that the extract of E. humifusa can inhibit directly the germination of the conidia of S. fuliginea, and it have the preventive effect on the disease caused by four strains come from four different regions in Shanghai, and it had a relative large antifungal table. Two main active substances were isolated. These results will be a base for further explorations of the E. humifusa extract to a phytochemical fungicide.