| Essential oil is widely and the use of essential oil is involved in daily necessities,health products and medicine and food industries.Thuja koraiensis Nakai is an evergreen tree,which is a precious economic tree with fragrant,ornamental and medicinal application.Therefore,the single factor experiment was carried out on the essential oil of Thuja koraiensis Nakai by steam distillation,and the extraction technology of the essential oil from the young and leafless old branches of Thuja koraiensis Nakai belt was optimized by orthogonal test and response surface optimization.The chemical components of the oil were analyzed by GC-MS,and the antibacterial activity and minimum concentration(MIC)of essential oil from the young branches and the leafless old branches of Thuja koraiensis Nakai cypress were detected by the method of filter paper.The following results are obtained:(1)Objective to optimize the extraction process of essential oil from young branches with leaves and old branches without leaves of Thuja koraiensis Nakai by steam distillation.The orthogonal test showed that three factors had significant effects on the extraction of essential oil from young branches with leaves and old branches without leaves of Thuja koraiensis Nakai,and the distillation time had the greatest effect on the extraction rate of essential oil from young branches with leaves of Thuja koraiensis Nakai,and the liquid-solid ratio had the greatest effect on the extraction rate of essential oil from old branches without leaves of Thuja koraiensis Nakai.The results showed that the best combination of the factors in the orthogonal test was distillation time 3 h,liquid-solid ratio 7 ml / g,Na Cl content 2%,and the extraction rate was 3.9%;Response surface optimization method showed that the extraction rate of essential oil was 4.30145% and the actual value was 4.4% under the conditions of liquid-solid ratio of6.9345ml/g,distillation time of 2.69 h and Na Cl content of 2.56%.The results showed that the optimal combination of the factors in the orthogonal test was distillation time 3 h,liquid-solid ratio 8 ml / g,Na Cl content 6%,and the extraction rate was 1.2%;Response surface methodology(RSM)showed that the extraction rate of essential oil was 1.1712% and the actual value was 1.3% under the following conditions: the ratio of liquid to material was 7.8804 ml / g,the distillation time was 2.23 h and the mass fraction of Na Cl was 6.56%.The results showed that the extraction process parameters of Thuja koraiensis Nakai essential oil from young branches with leaves and old branches without leaves were reliable and valuable.(2)Chemical constituents of essential oil from Thuja koraiensis Nakai of young branches with leaves and old branches without leaves.A total of 48 compounds were detected in the essential oil of young branches with leaves,accounting for 93.79% of the total essential oil.A total of 45 compounds were detected in the essential oil of leafless twigs,accounting for96.03% of the total essential oil.Carvoyl acetate was the highest content of the two essential oils,accounting for 22.43% of the total content of the essential oils from young branches with leaves and 22.84% of the total content of the essential oils from old branches without leaves.(3)Antimicrobial activity of essential oil from Thuja koraiensis Nakai of young branches with leaves and old branches without leaves.The antibacterial test showed that the essential oil of Thuja koraiensis Nakai of young branches with leaves and old branches without leaves had antibacterial effect on the three strains.The diameter of inhibition zone of essential oil from young branches with leaves to Staphylococcus aureus,Bacillus subtilis and Escherichia coli were13.28 mm,12.04 mm and 12.94 mm.The diameter of inhibition zone of essential oil from old branches without leaves to Staphylococcus aureus,Bacillus subtilis and Escherichia coli were10.00 mm,15.20 mm and 9.86 mm.The essential oil of Thuja koraiensis Nakai of young branches with leaves had the best antibacterial effect on Staphylococcus aureus with MIC value of 5?g/ml,followed by Bacillus subtilis and Escherichia coli with MIC value of 10 ?g/ml.The essential oil of Thuja koraiensis Nakai of old branches without leaves had the best antibacterial effect on Bacillus subtilis with MIC value of 0.625?g/ml.The MIC values for Escherichia coli and Staphylococcus aureus were 2.5?g/ml and 5?g/ml?(4)The essential oil of Thuja koraiensis Nakai was compared with that of young and old branches.Comparing the essential oil of young brabches and old brabches of Thuja koraiensis Nakai,the highest extraction rate of essential oil was 4.4% for young brabches and the highest extraction rate of essential oil was 1.3% for old brabches.Therefore,the extraction rate of essential oil from young branches with leaves is faster,the oil yield is higher,and the extraction effect is better.48 compounds were detected in the essential oil of Thuja koraiensis Nakai with young branches and 45 compounds were detected in the essential oil of old leafless branches.The highest content of the two essential oils was carvoyl acetate,accounting for more than22% of the total content,and most of the two essential oils were composed of alkenes and esters.In the essential oil from young branches of Thuja koraiensis Nakai,the main compounds different from the essential oil of old leafless branches are ?-phellandrene,limonene,norcamphor,cyclohexanol and Verbenone,and in the essential oil from old branches of Thuja koraiensis Nakai,the main compounds different from the essential oil of young branches are fenicone,hydrocortisone,eucalyptol and ?-Terpinene.Objective to compare the antibacterial activity of essential oil from young twigs with leaves and old twigs without leaves of Thuja koraiensis Nakai.The results showed that the essential oil from young branches of Thuja koraiensis Nakai had the best antibacterial effect on Staphylococcus aureus,and the essential oil of old leafless branch had the best antibacterial effect on Bacillus subtilis,and the essential oil of young leafed branch and old leafless branch of Thuja koraiensis Nakai had good antibacterial effect on the three strains.The MIC values of old branches of Thuja koraiensis Nakai essential oil against Bacillus subtilis and Escherichia coli were lower than those against young branches with leaves.Therefore,the antibacterial effect of the essential oil from old branches of Thuja koraiensis Nakai was higher than that from the young branches.Through the study on the essential oil of Thuja koraiensis Nakai's young branches with leaves and old branches without leaves,the possibility of development and utilization of Thuja koraiensis Nakai's essential oil as a natural antibacterial agent was further illustrated.On the one hand,it can further strengthen the application of Thuja koraiensis Nakai essential oil in food additives,especially in the field of bacteriostasis,so as to provide a certain scientific basis for the comprehensive utilization of Thuja koraiensis Nakai essential oil.On the other hand,it can be used as a reference for the comprehensive utilization of Thuja koraiensis Nakai essential oil ornamental and antibacterial properties of essential oil can be used in urban landscaping,especially in hospitals,sanatoriums and other places.It can play the greening,beautification,fragrant flowers and purification functions of Thuja koraiensis Nakai. |
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