Supercritical CO₂ Fluid Extraction Process And Antifungal Activities Of Essential Oil From Inula Britannica L.

Previous research shows that Inula britannica has good activity to certain plant pathogenic fungi, in order to have further study antimicrobial activities on the essential oil from I. britannica. Supercritical CO₂ fluid extraction technology was adopted to optimize extraction procedure of the essential oil from I. britannica flower, and antifungical activities of the essential oil against certain plant pathogenic fungi were tested. Conclusions are as follow:By the orthogonal experiments and using extraction quantity of the essential oil as the indicator, the influence of extracting pressure, extracting temperature, CO₂ flow rate and flower particle size on oil yielding rate were investigated, and suitable conditions were determined based on the single-factor tests. They were as follows: extracting pressure 30 MPa, extracting temperature 40℃, CO₂ flow 20 L/h, flower particle size 60 mesh. The yield of essentical oil was 10.01%.In order to clarify agricultural activities of the essential oil form I. britannica, antifungal activity was tested by the methods of mycelical growth, conidial germination and potted seedlings. The results showed the essential oil at the concentration of 4.0 g·mL?1 exhibited significantly fungicidal activities to the mycelium growth of eight fungicides. Gaeumannomyces graminis var. tritici and Phytophthora capsici Len were sensitive to the essential oil, and the inhibition rates were 100.00 % and 83.76 %, respectively;followed with the EC50 value of 311.06μg/mL and 411.30μg/mL, respectively. At the same concentration, the essential oil could strongly inhibit the spore germination of Phytophthora capsici Len and Fusarium oxysporum Schl. The inhibition rates were 98.26% and 96.54%, respectively. The EC50 against spore germination of Phytophthora capsici Len and release inhibition rates were 214.10μg/mL and 422.12μg/mL respectively. In the pot experiments, the protective and therapeutic efficacies of the essential oil from I. britannica at 1.0 mg/mL against the Phytophthora capsici Len were 46.59% and 26.93% （7 d）at the dosage of 5 mL. The protective efficacy has no different with the control of fungicide-Thiram at 800-fold dilution. The therapeutic efficacy was lower than Thiram at 800-fold dilution.A three-factor, three-level central composite design （CCD）was used to provide experimental data for establishing a regression model describing the SF-CO₂ extraction. The result shows extraction pressure had a significant effect on active ingredients of the essential oil from I. britannica.Through GC-MS analysis, 153 compounds were identified in the essential oil from I. britannica. They were mainly phenols, alcoholic compounds, alkyl hydrocarbons and their derivatives, others are heteroatomic compound, and so on. Activity tracking experiments indicated that sterilization compositions of the essential oil are mostly low polar components.