The Extraction Process Optimization And Antibacterial Activity Of Volatile Oil From Artemisia Annua L.

Artemisia annua L., one of the indigenous plants used in traditional Chinese medicine, is an annual herb which come from Artemisia. Compositae family. In this work. A. annua was used as a material to investigate the extraction process of volatile oil bv the method of ultrasonic assisted steam distillation. Meanwhile, the chemical constituents and antibacterial activity of volatile oil. extracted from fresh and dry A. annua. were studied by GC-MS and vitro tests of inhibitory bacteria. Similarly, the volatile oils of A. annua during four different stages were investigated. The main research results are as follows:1. The ultrasonic assisted steam distillation method was used to investigate the extraction process of volatile oil in A. annua. The result showed that the factors (including extraction time, ultrasonic time and ratio of solid to liquid) had a good effect on the extraction rate of volatile oil within a certain extent. And the increased ultrasonic power had inhibition to the extraction rate. We optimized the extraction process of ultrasonic assisted steam distillation for volatile oil:extraction time 4.9 h. ultrasonic time 1.6 h. and ratio of solid to liquid 1:9. Ultimately, we worked out the predicted extraction rate of 0.76% through the model and got the actual extraction rate of 0.73% by experiment. Considering the volatile oil extraction rate of 0.64% extracted by steam distillation, we got that this method could be used to explore the optimum conditions of volatile oil extraction and increased the extraction rate. It affected the composition of volatile oil by method of the ultrasonic assisted steam distillation. Contrast to the volatile oil extracted by steam distillation, the content of camphor and borneol rose by 4.88 and 3.05 percentage points separately and one extra composition of limonene was detected by 0.66 percentage points.2. The compounds of fresh and dry A. annua volatile oils were studied by GC-MS. The result showed that the extraction ratio of fresh and dry substance was 0.77% and 0.73%, respectively.25 compounds were identified in these volatile oils respectively. The relative content of the every component was different and there were different kinds of compounds in these two volatile oils.0.82% of thujone was found only in dry A. annua and 0.28% of isoeugenol only in dry. According the vitro tests of inhibitory bacteria, the essential oils had different inhibitory effects on Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhimurium. In the tests of MIC, we got that all the MICs were below 1%. Among them, the MIC of fresh A. annua volatile oil against Escherichia coli was below the dry by MIC<0.5%. At low volatile oil concentrations, the antibacterial activity of fresh A. annua volatile oils was more effective than the dry.3. In this study volatile oils of A. annua during four different stages were extracted, analyzed by GC-MS and were used to investigate the antibacterial activity. The result showed that the volatile oil extraction ratio of 0.81% was the highest for A. annua in flowing stage. According to GC-MS,21,23,21 and 22 components were identified in pre-flowering, initial flowering, flowering and post-flowering stages, representing 93.91%,95.34%,97.11% and 90.59% of the total detected constituents, respectively. There were differences in A. annua volatile oil category and content of four different stages. For the chemical classification of volatile oil, the content of total hydrocarbons decreased and total oxygenated compounds increased significantly from Pre-flowering stage to Post-flowering stage. According the vitro tests of inhibitory bacteria, the essential oils had different inhibitory effects on Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhimurium. The volatile oils in pre-flowering and initial flowering were significantly more effective than that in others for Staphylococcus aureus and Bacillus subtilis. For Escherichia coli, there were no significant differences in antibacterial effect of four volatile oils. In the tests of MIC, A. annua volatile oil in pre-flowering, initial flowering and post-flowering stages against Staphylococcus aureus were more effective than that in flowering stage by MIC<0.25%. For Bacillus subtilis, volatile oil in initial flowering and flowering stages were more effective than that in pre-flowering and post-flowering by MlC<0.5%. The volatile oil in pre-flowering was more effective than others for Escherichia coli by MIC<0.5%. The volatile oil in flowering showed the strongest antibacterial effect by MIC<0.25%.