Evaluation And Analysis On The Antifungal Activity Of Inula Japonica Extracts

The antifungal activity on the extract of I.japonica(Compositae)against the phytopathogenic fungi as well as the isolation and purification of main antifungal compounds were studied in this thesis.The antifungal activity of extracts from different parts of I.japonica was tested by the methods of mycelial growth,conidial germination, potted seedlings and detached leaves,the results showed that extracts from all parts of I. japonica exhibited different antifungal activities on Sphaerotheca fuliginea, Pseudoperonospora cubensis,Colletotrichum orbiculare,Botrytis cinerea,Alternaria solani,Phytophthora infestans and Fulvia fulva,the antifungal activity of extract from flowers was stronger than those from the other parts.The extraction condition for the flowers was optimized.A simple,convenient,economic and effective method was ascertained,In which the flowers were smashed,passed the sieve of 40 mesh,then the powder was extracted twice(each for 3 hours)with 95%ethanol under the temperature of 50℃.Ratio of the weight of powder and the cubage of the solvent is 1:10 during the first extraction,then the ratio of 1:8 was used in the second time.The extracting solution was obtainded by filtration,then it was concentrated to dry by a rotary evaporative apparatus (60℃,0.1MPa).According to this method,the flowers powder of 25kg was extracted, 2.55kg dry paste was obtained,and the yield of dry extract was 10.21%.Aqueous suspension of ethanol crude extract was partitioned with different polarities of solvents successively,such as petroleum ether,chloroform,ethyl acetate,and n-Butanol saturated of water,the five fractions were obtained by concentrating the extracts under the reduced pressure.Antifungal activities were tested,it showed that the five paste extracts had different inhibitory activities against S.fuliginea,P.cubensis,B.cinerea,A.solani and P. infestans,Among the extracts partitioned with different polarities of solvents,the fraction from chloroform was more effective than the fractions from the other 4 solvents.The crystal product named J2 was separated from chloroform fraction by column chromatography,thin layer chromatography and recrystallization.Based on the melting point and spectral analysis of UV,IR and NMR,J2 was identified as 1-O-Acetylbritannilactone(ABL).A method of high performance liquid chromatography was used for the determination of the purity of sample J2(it's purer than 99.5%)and the content of ABL in the crude extract(it's 2.45%),then the content of ABL in I.japonica was calculated(it's about 0.25%).Antifungal activity of compound ABL against six phytopathogenic fungi was tested,the inhibitory effect was significant,the inhibiting rate of compound ABL against the germination of cystospores of P.infestans by 100%at the concentration 0.1mg/mL.The 0.62%1-O-Acetylbritannilactone EC was prepared by mixing the crude extract of flowers with anhydrous ethanol and the emulsifier of tween 80 in the ratio of 200:1000:1(w,v,v)throughtly,then it was used for controlling cucumber downy mildew in the greenhouses and plastic tunnels.It had a promising control efficacy and a great potentiality to be developed as one of good plant-derived fungicides.