Primary Study On Antifungal Activity Of Plant Extracts

It is an important way to search new fungicides from plants. There are abundant resources from plants in China, which is an ideal area. The research was based on screening of antifungal plants in China . The fungistatis of 15 plants (17 plant samples) acetones extracts were systematically tested with Botrytis cinerea Pers. Rhizoctonia solani. Fusarium oxysporium Schl., Cladosporium cucumerinum Ell. et Arthur and Alternaric solani (Ellis et Martin) Jones et Grout ,and Stellera chamaejasme and Xanthium sibiricum , which have higher antifungal activity ,were studied further. The results were as following:1. By testing the vitro activity of 17 plant samples acetones extracts(the concertration was 0.1 g /ml) against 5 pathogenic fungi, we found that the extracts inhibition of hypha of Stemona japonica, Xanthium sibiricum(the root,the stem and leaf), Solatium nigrum, Artemisia annua, Sophora flavescens and Stellera chamaejasme were more than 80% to one or more tested fungi, and that of the former 4 plant extracts even got to 100% to at least one tested fungi; In the spore emergence test, the acetone extracts of 7 plant samples, such as Euphorbia helioscopia, Solarium nigrum, Sophora flavescens, Arlomisia annua, Xanthium sibiricum(the root,the stem and leaf), Taraxacum ongolicum , had more than 90% inhibition rate to at least one tested fungi, the antifungal ratio of extracts of the stem and leaf of Xanthium sibiricum even reached 100%.2. According to the vitro test , the extracts(the concertration was 0.1g /ml) of 7 plant samples that had strong inhibition are tested aginst tomato gray mould and cucumber powdery mildew on living entity. The controlling effect of the extracts of Xanthium sibiricum(the stem and leaf) was the best on cucumber cotyledons, and on the tomato fruits, Xanthium sibiricum(the stem and leaf) . Solanum nigrum, Artomisia annua and Stemona japonica extracts had control rate above 40%; In the pot tests, the protective efficacy of the Xanthium sibiricum(the root) , Stemona japonica , Sophora flavescens and Artomisia annua extracts were stronger against cucumber powdery mildew, after spraying 8 days,the protective efficacy were all above 68%,whereas,the curative efficacy of Xanthium sibiricum(the root) and Artomisia annua extracts were the highest, after spraying 8 days,their curative efficacy was 93.55% and 76.34% respectively.The plants mentioned above are worthy of being studiedfurther.3. In the further study on higher active plants, Xanthium sibiricum and Stellera chamae-jasme were researched systemically. Through vitro test of different solovent extracts, screening the optium extracting solovent of Xanthium sibiricum (stems and leaf) was acetone,and that of root of Xanthium sibiricum and Stellera chamaejasme were carbinol and ethanol individually; The extracting methods test showed that the antifungal activity of different methods extracts were almost the same,but the inhibition of the extracts of the reflux extracting method was higher relatively.4. Using column chromatography and tabular chromatography,the optimum solovent and method extracts of Xanthium sibiricum (root,stem and leaf) and Stellera chamaejasme were isolated primarimily,and the antifungal compositions of them were analysized with gas chromatography and mass spectroscopy (GC-MS).13 compounds were identified as 6-[1-(acetyloxy)-3-oxobutyl]-3,3a,4,7,8,8a-hexahydro-7-methyl-3-methylene-2H-Cyclohepta[a] furan-2-one and 7-hydroxy-4-methyl-4-(propan-2-on-l-yl)-Tricyclo[3,3,0,0(2,8)]octan-3- one et al. from Xanthium sibiricum (stems and leaf); 21 compounds were identified as N-phenyl-1- Naphthalenamine , Dehydrocostuslactone, Dibutyl phthalate et al. from root of Xanthium sibiricum; 23 compounds were identified as N-phenyl -2-Naphthalenamine, Bis(2-ethylhexyl) phthalate, Di-n-octyl phthalate et al. from Stellera chamaejasme.