| In this paper, the extraction of volatile oil from propolis, composition identificat- ion, physical and chemical properties, DPPH radical-scavenging activities, and antifu- ngal activity against Ascosphaera apis were studied. The results were summarized as follows:(1) Petroleumether, hexane, diethyl ether, tetrachloromethane, respectively, were used to extract volatile oil from propolis. The yeild of volatile oil were compared to choose the optimum solvent, and petroleumether was regarded as the optimum solvent. The orthogonal experiment was carried out to determine the optimum condition of extraction assisted by microwave–ultrasound technique, and the optimum conditions turned out to be solid-liquid ratio at 1:20, the extraction temperature at 40℃, micro- wave power at mid-range power, extraction time of 15 min. in this case, the yeild of volatile oil reached at as high as 12.32%, which proved the feasibility of this new technology.(2) The compositions of four kinds of volatile voils-PEP, HEP, TEP and DEP were analyzed by GC-MS. The results showed that 60 compounds were identified in PEP, 49 compounds in HEP, 46 compounds in TEP, 47 compounds in DEP, and the relative contents of volatile oils were 34.18%, 30.03%, 47.66%, 35.14% respectively. The major components of the volatile oils were alkanes, alkenes, alcohols, acids, aldehydes, esters etc, but differed greatly in content, which indicated that the polarity could affect the extract of volatile substance.(3) Nine physical and chemical properties of PEP were detected according to National Standard: the oil was an yellow transparent oily liquid, with aromatic flavor; at 25℃, relative density of PEP was 0.936, refractive index was 1.43505, melting range was about 25℃~47℃, freezing point was 24℃, 1 mL of the volatile oil was insoluble in 17.6 mL of 90% alcohol solution; volatile oil acid value, ester value were 14.8, 16.7 respectively; content of carbonyl compounds and phenols were 11.8%, 60.4% respectively.(4) DPPH radical-scavenging activity was tested to evaluate the antioxidant activity of propolis and four volatile oils—TEP, PEP, HEP and DEP. Duncan multiple comparison showed that there were extremely significant difference (P<0.01) among antioxidative activitiy of TEP, PEP, HEP and DEP. the order of antioxidative activitiy was: TEP>PEP>HEP>DEP. TEP and propolis had strong antioxidative activitiy, which showed no significant difference at the level of 5%, both of them showed significant scavenging activity to DPPH freeradical. All the activities had an dose-effect relationship, DPPH radical scavenging rate depended on the concentration, the higer the better. IC50 were approximately at 5μg/mL, 10μg/mL, 50μg/mL, 200μg/mL respectively,TEP showed strong antioxidant activity due to the high content of flavonoids such as Pinocembrin and galangin. DEP had a very weak antioxidant activity, which may be due to the lack of esters and phenols.(5) Growth Rate method and Tube Dilution method were used to evaluate antifungal activity of propolis and volatile oil PEP against Ascosphaera apis, which effects were compared with that of nystatin, and the mechanism was discussed. Propolis showed a better antifungal activity than volatile oil, which may attribute to higher flavonoids content in PEP than in propolis. At high concentration, PEP showed a good activity, and the activity of nystatin was the best. The minimum inhibitory concentration of Propolis, PEP, nystatin were: 0.078 mg/mL, 0.156 mg/mL, 0.156 mg/ mL respectively, the MIC of EEP and PEP is lower than nystatin, which indicated that volatile oil and propolis had a good antifungal activity against Ascosphaera apis.
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