| Melaleuca bracteata is evergreen trees which is belong to Myrtaceae, Melaleuca.Melaleuca bracteata not only has some high ornamental value and strong adaptability, and its leaf is rich in plant essential oil. Melaleuca bracteata essential oil has full-bodied aroma, and with a variety of biological activity, it shows a good application potential in antioxidant, antibacterial, insect-resistant, etc. This test used Melaleuca bracteata which came from fujian local as raw materials, to studied the extraction technology, composition analysis, antioxidant activity and antimicrobial activity of Melaleuca bracteata essential oil. The results showed that:1?Used organic solvent extraction method to extract Melaleuca bracteata essential oil, and to discuss the main factor which influences the extraction yield.The result indicated that the optimum extraction condition was that:extraction time 3h, extraction temperature 50?, material-liquid ratio 1:20. The essential oil extraction yield is 4.51% under the optimum extraction condition. The primary and secondary order of the main factor which influenced the extraction yield was:extraction time> material-liquid ratio> extraction temperature.2?Response Surface Methodology (RSM) was used for optimizing the ultrasonic-assisted extraction of melaleuca bracteata essential oil. On the basis of single-factor experiments, ultrasonic power,extraction time and material-liquid ratio were selected as influencing factor during extraction. The experiment mathematical model was arranged according to Box-Behnken central composite experiment design. The optimal extraction conditions were found as follows:ultrasonic power 389.5W, ultrasonic time 21min and material-liquid ratio 1:20. Under such conditions, the highest yield of essential oil reached with estimated value was 4.542% and verified value was 4.536%. The primary and secondary order of the main factor which influenced the extraction yield was: material-liquid ratio> ultrasonic time> ultrasonic power.3?Using gas chromatography-mass spectrometry (GC-MS) technical analyze, identify and compare the chemical composition of Melaleuca bracteata essential oil extracted by head space solid-phase microextraction method, hydro-distillation method, supercritical CO2 fluid extraction method, ultrasonic-assisted extraction method and organic solvent extraction method. The Study found that the Melaleuca bracteata leaves detected 76 kinds of volatile compounds extracted by HS-SPME, they accounted for 97.28% of the total peak areas. The Melaleuca bracteata leaves detected 37 kinds of volatile compounds extracted by hydro-distillation method, they accounted for 99.67% of the total peak areas. The Melaleuca bracteata essential oil detected 61 kinds of volatile compounds extracted by supercritical CO2 fluid extraction method, they accounted for 96.65% of the total peak areas. The Melaleuca bracteata leaves detected 42 kinds of volatile compounds extracted by ultrasonic-assisted extraction method, they accounted for 98.50% of the total peak areas. The Melaleuca bracteata leaves detected 41 kinds of volatile compounds extracted by organic solvent extraction method, they accounted for 96.72% of the total peak areas. Based on the analysis and comparison of the volatile compounds of Melaleuca bracteata leaves extracted by five kinds of methods, it found that the volatile compounds of Melaleuca bracteata leaves mainly include the following compounds:ethers, alkene, esters, alcohols, phenols, aldehydes, ect. The relative content of ethers was highest and the main ingredients was Eugenol methyl.4?Adopted the DPPH assay, determination of reducing power and ABTS assay for determining the antioxidant activities of Melaleuca bracteata essential oil extracted by hydro-distillation method, supercritical CO2 fluid extraction method and ultrasonic-assisted extraction method. Tests showed that the Melaleuca bracteata essential oil with strong DPPH radical scavenging capacity, and also has a certain reducing power and the ABTS+radical scavenging activity, removing force present a tendency of increasing with the increase of concentration of essential oils. The scavenging activity increased with the increase of concentration of essential oils.5?The melaleuca bracteata essential oil extracted by hydro-distillation as the sample, to research its antibacterial activity against Pseudomonas aeruginosa PAO1, Chromobacterium violaceum ATCC31532, Serratia marcescens H30, Serratia marcescens MG1 and Staphylococcus aureus ATCC25933. Filter method was used to determine the antibacterial ability of melaleuca bracteata essential oil against the five test bacteria. The result indicated that antibacterial effect of essential oils against Chromobacterium violaceum ATCC31532 was the most significant, and the inhibit circle diameter was larger with the increase of concentration of essential oils, when the concentration of essential oil was 40mg·ml-1,the inhibition of circle diameter was 18.53±0.60mm. In addition, The melaleuca bracteata essential oils had certain antibacterial activity against Pseudomonas aeruginosa PAO1, Serratia marcescens H30 and Serratia marcescens MG1. Used broth trace dilution method to determinate MIC and MBC. The result indicated that the melaleuca bracteata essential oil had strongest antibacterial and sterilization ability against Chromobacterium violaceum ATCC31532, the MIC was 2.5mg·ml-1, the MBC was 5mg·ml-1. The melaleuca bracteata essential oil had the same antibacterial and sterilization ability against Pseudomonas aeruginosa PAO1, Serratia marcescens H30 and Serratia marcescens MG1, the MIC were 5mg·ml-1, the MBC were 10mg·ml-1. The MIC of melaleuca bracteata essential oil against Staphylococcus aureus ATCC25933 was 5mg·ml-1, the the MBC were 20mg·ml-1. |
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