| Essential oils are important plant secondary substances, which have many factors such as a diverse bioactivity, novel mechanism, naturalness, do not pollute, etc. In antibacterial, anticorrosive they have shown good potential application.In this paper, essential oils of 5 kinds of plants were extracted by steam distillation, with 10 important plant pathogenic fungi and 11 pathogenic bacteria used as test bacteria. And the antifungal activity of essential oils was determined by mycelium growth rate method. The sensitivity of pathogenic bacteria was determined by filter paper method. The minimum inhibitory concentration MIC of 5 kinds of essential oils to 11 pathogenic bacteria's, and the insecticidal activity of essential oils to Tribolium castaneum(Herbst) were determined by vitro method. This paper also states the study of the feasibility of essential oils applied to gaseous corrosion, and the development of mouthwash formula in which essential oil was added. The results as follows:Antibacterial activity of the 5 plant oils, Citrus reticulata Blanco essential oil, Pittosporum kwangsiense Chang et Yan essential oil, Ageratum conyzoides Linn essential oil, Erigeron acer Linn essential oil and Litsea mollis Hemsl essential oil against 10 experimented bacteria, Colletotrichum gloeosporidides(Penz.) Sacc, Sphaceloma fawcettii Jenkins, Fusarium oxysporum f sp niveum (E. F. Smith) Syn. et Hans, Pestalotia mangiferae P. Herm, Cercospora kaki Ell.et Ev., Glorosprium musarum Cookeet Mass, Colletotrichum graminicola (Ces.) Wilson., Mycosphaerella sentina (Fr.) Schroeter, Gymnosporangium haraeanum Syd and Pyricularia oryzae Cav was tested. The results showed that Ageratum conyzoides Linn. essential oil and Citrus reticulata Blanco essential oil against the tested bacteria had highly inhibitory effect, with inhibition rates of above 77.27% and 63.54% against 10 plant pathogenic fungi at 1μL/mL. The toxicity of Citrus reticulata Blanco essential oil and Ageratum conyzoides Linn. essential oils to 10 plant pathogenic fungi were determined, the results showed that EC50 values of Citrus reticulata Blanco essential oil to 10 plant pathogenic fungi was between 0.2316μL/ml～0.5653μL/ml and EC50 values of Ageratum conyzoides Linn. essential oil to 10 plant pathogenic fungi hyphae was between in 0.0573μL/ml～0.1943μL/ml. The toxicity of Ageratum conyzoides Linn. essential oil against Glorosprium musarum Cookeet Mass was showed as the greatest impact among the 10 plant pathogenic fungal, while against Colletotrichum gloeosporidides(Penz.) Sacc showed as the smallest impact. The toxicity of Citrus reticulata Blanco essential oil against Mycosphaerella sentina (Fr.) Schroeter was found as the biggest value, but against Cercospora kaki Ell.et Ev. was the smallest value.Antibacterial activity of 5 kinds of essential oils was tested on 11 experimented bacteria: Bacillus cereus Frankland, Bacillus megaterium de Bary, Bacillus subtilis (Ehrenberg) Cohn, Staphyloccocus aureus Rosenbach, Micrococcus lysodeikticus Fleming, Micrococcus luteus(Schroeter) Cohn, Proteus vulgaris Hauser, Pseudomonas aeruginosa (Schroeter) Migula, Shigella dysenteriae (Shiga) Castellani & Chalmers, Salmonella typhi (Schroeter) Warren & Scott, Escherichia coli (Migula) Casleillii and Chalmers. The results showed that Citrus reticulata Blanco essential oil, Ageratum conyzoides Linn essential oil, Erigeron acer Linn essential oil and Litsea mollis Hems against pathogenic bacteria had highly inhibitory effect. And the minimum inhibitory concentration (MIC) of 4 essential oils to 11 pathogenic bacteria was between in 0.0625μL/ml～4μL/ml, the order of antibacterial activity of several essential oils from high to low is:Litsea mollis Hemsl. essential oil>Ageratum conyzoides Linn.essential oil> Citrus reticulata Blanco essential oil> Erigeron acer Linn. essential oil.Main chemical components of 4 essential oils were analyzed by GC/MS,18 compounds were found in Litsea mollis Hemsl essential oil, which mainly contains D-Limonene and 2,6-Octadienal,3,7-dimethyl-, (Z)-,2,6-Octadienal,3,7-dimethyl-, (E)-, D-Limonene accounting for 33.52% of the total.28 compounds were found in Erigeron acer Linn. essential oil bergamotene and cubebene was the chief constituent of Erigeron acer Linn. essential oil, occupying 14.2312% and 16.7254% of the total respectively,13 components were identified in Ageratum conyzoides Linn. essential oil, which contains Caryophyllene, PrecoceneⅠ, PrecoceneⅡ, accounting for 24.9996%,27.9857%,34.0382% of the total respectively.26 compounds were found in Citrus reticulata Blanco essential oil, which consists mainly of (3-myrcene and thymol, accounting for 21.1789%,20.0652% of the total respectively.The fumigation activity of 5 essential oils was determined on mold, mixed bacterial, Saccharomyces cerevisiae, the results showed that the inhibit effect of Litsea mollis Hemsl esshential oil and Citrus reticulata Blanco essential oil on the common types of environmental mold was good. The time of onset of mold of the PDA agar plates wass prolonged from 1 day to 5 days by fumigation with Litsea mollis Hemsl. essential oil at 8μL/dish. Ageratum conyzoides Linn. essential oil could prolong the time of onset of mold of the PDA agar plates from 1 day to 8 days. Fumigation action of 5 essential oils against mixed bacterial was less effectiveness. Growth of mixed bacterial on PDA agar plates could be slowed by fumigation action of Litsea mollis Hemsl essentialk oil and Citrus reticulata Blanco essential oil. Growth of Saccharomyces cerevisiae was stoped by Litsea mollis Hemsl essential oil in 3 days, Proliferation of Saccharomyces cerevisiae was controlled by Citrus reticulata Blanco essential oil, only a few of Saccharomyces cerevisiae had grown. In antiseptic experiment with bread, the one was added with some Litsea mollis Hemsl essential oil didn't go moldy in the first 4 days, Citrus reticulata Blanco essential oil could stop mould growth in bread.Litsea mollis Hemsl essential oil was applied to develop mouthwash liquid, Litsea mollis Hemsl essential oil and ricinoleth-40 were mixed in 1:3 proportions to maximize the solubility in the water in the experiment of emulsifier levels. Comparison test of sterilization rate of water and essential oil unilateral mouthwash showed that rinse mouth with clean water could not effectively get rid of oral bacterial, however the bacterial eradication rate for essential oil solution was above 12%. To select the best experiment program of mouthwash formula by means of the orthogonal test, it showed that the integrated evaluation score of the experiment of 6 (A2B3C1D2) was the highest. The content of Litsea mollis Hemsl essential oil was the main factor affecting the score, next was the content of xylitol which was followed by sodium dehydroacetate and citric acid. Taking all factors into consideration, and identified Scheme A2B3C1D2 was the best one. The difference between the market sales mouthwash liquid and the newly-formulated essential oil-containing mouthwash liquid was not obvious; the bacterial eradication rate of the newly-formulated essential oil-containing mouthwash may be relatively large.Under the concentration of essential oil at 20μL/L, the fumigation activity of 5 essential oils against Tribolium castaneum (Herbst) was absent. The repellency ratio of essential oil to Tribolium castaneum (Herbst) was above 84.4%. The repellency ratio decreased when the time went longer. The contact toxicity of 5 essential oils against Tribolium castaneum (Herbst) was determined. The mortality of Ageratum conyzoides Linn essential oils against Tribolium castaneum (Herbst) was 33.3% at 100μL/dish, and the contact toxicity of others essential oils was extremely low. Ageratum conyzoides Linn essential oil and Citrus reticulata Blanco essential oil against acetyl cholinesterase and glutathione transferase of Tribolium castaneum (Herbst) were determined. Two essential oils inhibited the enzyme activity in a short time, the two enzyme activity gradually increased when time went longer. It was concluded that the tolerance of Tribolium castaneum (Herbst) to essential oil had increased. |
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