Study On The Antioxidant And Antibacterial Effects Of Origanum Essential Oil In Vitro

The goal of the experiment is to compare the antimicrobial and antioxidant of the Xishuang Banna Origanum essential oils in vitro.The Origanum essential oils was extracted by three different methods,they are steam distillation, microwave-assist steam distillation and simultaneous distillation extraction. Then we use GC-MS to analysis the volatility composition of the essential oils before the antimicrobial and antioxidant experiment.The results are as follows:1.GC-MS analysis on the Origanum essential oils1.1 Comparative analysis on the extraction efficiency and effectsAfter multiplicating experiments,we have the final extraction efficiency results of the three,they are 1.493%,2.064%and 1.737%respectively. And the orders are as follows:SDE extraction> microwave-assist steam distillation> steam distillation.1.2GC-MS results of the Origanum essential oilsIdentity 79 peaks from Steam distillation,the relative proportions are 94.97%.Identity 71 peaks from SDE,the relative proportions are 97.38%.Identity 40 peaks from microwave-assist steam distillation,the relative proportions are 96.84%.The content of alcohol and alkene in the Origanum essential oils are relatively high,the relative content are 53.11%and 30.93%for Steam distillation,55.16%and 33.1%for SDE,48.73%and 35.41%for microwave-assist steam distillation,respectivelyThere are eight kinds of the same olefins and alcohol in the chemical composition of the essential oils,but the relative content of each material is different.There are four kinds of Olefins which content more than 3%,they are B-phellandrene,1,4-cyclohexadiene,carenen and Carypophyllene.There is no obvious difference among the total olefin content in the essential oils which shows that the kinds of methods give a scarcely influence on the main olefin of the essential oils.Comparing on the peculiar composition of the three methods,we find out that steam distillation has more high molecular weight alkane,alcohols and acids.SDE has more phenols,aldehydes and esters.Microwave assist steam distillation has more olefins.2.Comparative study on the antioxidant effects of Origanum essential oils in vitro2.1 Comparative analysis on the scavenging free radicals effects of Origanum essential oils in vitroThe experiment compare the scavenging rate and IC50 of the Origanum essential oils to O2-,DPPH and·OH as well as reduction power.The results show that the Scavenging free radicals effects of Microwave assist steam distillation is the best among the three methods.2.2Comparative study on the DNA oxdative damage protection of the Origanum essential oilsThe results shows that Origanum essential oil can inhibit the emerge of linear DNA and open loop DNA to some extent,It can also protect DNA from oxidation damage and keep the DNA chain in natural double helix,the protection is concentrationdependent.3.Comparative study on the antibacterial effects of Origanum essential oils in vitroThe minimal inhibitory concentration of tested bacterial strain is carried out by drug-containing plate cell culture,the inhibition zone diameter is carried out by cylinder plate method, the sensitivity analysis of the bacteria is carried out under 4mg/mL concentration.3.1 Comparative study on inhibitory effects of Origanum essential oils to tested bacterialAccording to the MIC of tested bacterial,we can conclude that the inhibitory action of Origanum essential oil to Escherichia coli are the best,in the contrary,the inhibitory action to Aspergillus niger are the worst.Under the same concentration,the inhibitory action of the Origanum essential oils to tested gram-negative bacterium are better than the gram-positive bacterium. The inhibitory action of the essential oils extracted by three methods to Saccharomyces cerevisiae are all better than Aspergillus niger, the inhibitory action of SDE essential oil and microwave assist steam distillation essential oil to Saccharomyces cerevisiae are all better than steam distillation.According to the inhibition zone diameter of the tested bacteria and the sensitivity analysis results under 4mg/mL,we can see that the inhibitory action of Origanum essential oils to Escherichia coli are better than the other two tested bacterial,the results give a further proving to the MIC results.The inhibitory action of Origanum essential oil to tested bacteria are better than fungus,the inhibitory action to Saccharomyces cerevisiae are better than Aspergillus niger. In contrast,the inhibitory action of SDE to tested fungus are better than the other two methods.3.2 Comparative study on inhibitory effects of Origanum essential oil and tea tree oil to tested fungusThe inhibitory efficiency of Origanum essential oil and tea tree oil to Escherichia coli are about the same, the inhibitory action of the two kinds of essential oil to gram-negative bacteria are better than gram-positive bacteria,and the inhibitory action of Origanum essential oil to Bacillus subtilis is better than that of tree tea oil.The inhibitory action of Origanum essential oil and tea tree oil to tested bacteria are better than fungus,in the same concentration, the inhibitory to Saccharomyces cerevisiae are better than Aspergillus niger.According to the inhibition zone diameter of the tested bacteria and the sensitivity analysis results under 4mg/mL, we can conclude that the result of the inhibition zone diameter gives a further prove to the conclusion above,further more, accord ing to the inhibition zone diameter we also find out that the inhibitory action of Origanum essential oil to Bacillus subtilis is better than tea tree. The inhibitory actions of those two kinds of essential oils to Saccharomyces cerevisiae are about the same,but both of tthem are poor in Aspergillus niger inhibition. But in the same concentration, the total inhibitory effects to the tested fungus of tea tree oil is better than Origanum essential oil.