Studeies On High-Efficiency Extraction、Antioxidant Activities And Liposome Preparation Of Bergamot Essential Oil

Bergamot is a Citrus plant of Rutaceae and has the functions of phlegm,relieving cough and asthma.It also has various pharmacological effects such as anti-inflammatory,antibacterial,anti-oxidation,blood pressure lowering,anti-tumor and anti-depression.Bergamot essential oil is one of the main pharmacological active ingredients of bergamot,but at present,the bergamot essential oil extraction technology still has problems such as low extraction rate,insufficient material extraction,and high equipment cost,need to optimize its extraction technology.In addition,bergamot essential oils are volatile,easy to oxidize,and poorly water soluble,this limited their application.Based on this,we extract bergamot essential oil by low temperature continuous phase change extraction technology,and optimizes its extraction process;Then evaluated it in vitro and in vivo for its antioxidant activity;Preparation,characterization of bergamot essential oil liposomes,study its stability.The main research contents and results are as follows:（1）Study on the efficient extraction process of bergamot essential oil.The extraction process of bergamot essential oil was studied by low-temperature continuous phase change technology.The extraction process was evaluated by using the bergamot essential oil yield and pharmacological composition as indicators.The results showed that the optimum process conditions for extracting bergamot essential oil by low temperature continuous phase transformation technology is:the extraction temperature was 50.4°C,the extraction pressure was 0.62 MPa,and the extraction time was 61 min.Under this condition,the yield of bergamot essential oil is 8.29‰,and the relative percentage of essential oil active ingredients is 85.24%.（2）Evaluation the antioxidant activity of bergamot essential oil in vitro.The in vitro antioxidant activity of bergamot essential oil was evaluated by DPPH free radical scavenging ability,ABTS free radical scavenging ability,hydroxyl radical scavenging ability,total reducing power,lipid peroxidation inhibiting ability andβ-carotene bleaching method.The results showed,the IC₅₀ value of phoenix essential oil scavenging DPPH free radicals is 0.94 mg/m L,the Vc IC₅₀ value is 0.014 mg/m L,and the V_E IC₅₀ value is 0.03 mg/m L;The IC₅₀ value of bergamot essential oil for removing ABTS free radicals is 0.056 mg/m L,and the V_E IC₅₀ value is 0.032 mg/m L;The IC₅₀values for scavenging hydroxyl radicals were:1.68×10^-5 mg/m L for V_C,1.93×10^-5mg/m L for bergamot essential oil,and 3.67×10^-5 mg/m L for V_E.;The total reducing power of bergamot essential oil is generally weaker than V_C and V_E,and the total reducing power of concentration of 4 mg/m L is equivalent to V_C（p>0.05）;The inhibitory effect of bergamot essential oil on lipid peroxidation was inferior to that of V_E at the same concentration,but stronger than V_C.The inhibition rate was 85.27%when the concentration was 4.0 mg/m L;The inhibition rate ofβ-carotene bleaching by bergamot essential oil 1.0 mg/m L was 31.63%,significantly lower than 71.52%of V_Eat this concentration（p<0.05）,when the concentration of essential oil reached 3 mg/m L,the inhibition rate was 72.87%.（3）Evaluation of the antioxidant activity of bergamot essential oils in vivo.Using C.elegans as the research object,the in vivo antioxidant activity of bergamot essential oil was determined by measuring the lifespan,related physiological indicators and antioxidant indices of C.elegans;Determination of survival rate of C.elegans under heat stress and paraquat-induced oxidative stress.The results show that compared with the blank control,the life extension rate of bergamot essential oil to C.elegans at concentrations of 20μg/m L,50μg/m L,and 100μg/m L was 31.70%,22.54%,and11.85%.Different concentrations of bergamot essential oil had no significant effect on the number of eggs laid and the frequency of head swing（p<0.05）.On the 10th and16th day,20μg/m L and 50μg/m L bergamot essential oil can significantly improve the motility and mobility of nematodes and delay the muscle aging rate of nematodes（p<0.05）;20μg/m L,50μg/m L,and 100μg/m L bergamot essential oil had significant scavenging effects on ROS accumulation in C.elegans（p<0.05）,reduced by 24.99%,16.81%,and 14.61%;20μg/m L,50μg/m L,100μg/m L bergamot essential oil significantly increased SOD activity in C.elegans（p<0.05）,increased by 89.12%,59.03%,14.53%;20μg/m L,50μg/m L bergamot essential oil significantly increased CAT enzyme activity（p<0.05）,increased by 124.59%,82.92%;The MDA content of Caenorhabditis elegans in the 20μg/m L,50μg/m L,100μg/m L bergamot oil samples decreased by 58.57%,45.71%,and 34.29%;Under heat stress conditions,the survival rate of Caenorhabditis elegans in the 20μg/m L,50μg/m L,100μg/m L bergamot oil samples increased by 25.40%,32.54%,and 8.73%（p<0.05）;Under oxidative stress conditions,the survival time of Caenorhabditis elegans in the 20μg/m L,50μg/m L,100μg/m L bergamot oil samples increased by 21.33%,25.33%,and 36.0%（p<0.05）.（4）Study on preparation process and stability of bergamot essential oil liposomes.Stduy the effects of homogenization pressure,homogenization frequency,phospholipid/cholesterol ratio,essential oil addition and hydration time on liposome size,zeta potential,PDI polydispersity index and encapsulation efficiency.Study on micromorphology,centrifugal stability and storage stability of bergamot essential oil liposomes prepared under optimum processing conditions.The results show that the best preparation process is:homogeneous pressure 120 MPa,5 times homogenization,phospholipid/cholesterol ratio 5:1,essential oil addition 3.5 mg/m L,hydration time 75min,the liposome prepared under these conditions has a particle size of 183.53±2.39nm,PDI polydispersity index is 0.147±0.032,the Zeta potential value is 38.75±0.93m V,and the encapsulation efficiency is 47.23±0.54%;TEM to observe that the liposome is irregularly spherical,can clearly see the bilayer structure.Centrifugation at10,000 rpm/min for 2 min,5 min without delamination;After storage at 4°C for 30 d,the particle size increased from 183.53±2.39 nm to 223.57±1.34 nm,increasing by21.8%;The zeta potential decreased from 38.75±0.93 m V to 28.36±1.02 m V,and the essential oil retention rate was 85.03%.