Study On Antibacterial Activity Of Several Essential Oils

The using of chemical bactericides had caused a huge harm to environment, it’s extremely urgent to develop an efficient, low toxic, environmentally friendly bactericide. Essential oils have showed a great potential in the development and utilization of bactericide with good antibacterial.The antimicrobial activities of 9 EOs were determined with resazurin colorimetric-microdilution method. The joint actions of selected essential oils were evaluated. The components of several oils were analyzed with GC-MS.The main results were as follows:1. The essential oils were extracted with steam distillation from 5 bamboo leaves, namely, Indocalamus longiauritus, Bambusa vulgaris Schroder, Pleioblastus yixingensis, Chimonocalamus delicates, and B.blumeana Schult. The yield ratios were 0.026%,0.026%, 0.024%,0.04% and 0.021%, respectively.2. The inhibitory activity against several common bacterial of 4 kinds of bamboo EOs were evaluated with resazurin colorimetric- microdilution method. The results showed that the MICs of the EO extracted from B.blumeana Schult leave were 192μg/mL, 48μG/mL,192μg/mL,96μg/mL,192μg/mL, respectively against B. thuringiensis, B. subtilis, P. solanacearum, S. aureus and E. coli The MICs of Indocalamus longiauritus oil were 160μg/mL,160μg/mL,160μg/mL,160μg/mL,160μg/mL. The MICs of Chimonocalamus delicates oil both were 250μg/mL. And the MICs of Pleioblastus yixingensis oil were 375μg/mL,375μg/mL,750μg/mL,375μg/mL,750μg/mL. The antibacterial activities of the oils from bamboo leaves were B.blumeana Schult> Indocalamus longiauritus>Chimonocalamus delicatus>Pleioblastus yixingensis. Lemon oil had better antibacterial activities, which MIC was 80μg/mL against S. aureus.3. The joint actions of selected essential oils were evaluated. The results showed that the mixted oil from B.blumeana Schult and Indocalamus longiauritus leaves mixed with concentration ratio of 5:1 showed the best activity. The MICs against P. solanacearum and E. coli both were 148.6μg/mL, and the MICs against B. thuringiensis and E. coli both were 297.1μg/mL. With the reduction of the proportion of oil from B.blumeana Schult leaves, the inhibitory activity of the mixed oil against 5 kinds of bacteria were also reduced. As can be seen from the values of FICI, all complex oils exhibited antagonism, except the mixed oil from B.blumeana Schult and Indocalamus longiauritus leaves with concentration ratio of 5:1 in those 15 groups of complex combinations.4. The inhibitory abilities of 3 oils against 3 kinds of fungus were evaluated with mycelium growth rate method. The results showed that the antifungal ability of 3 oils for the test were significantly higher than the oil from Indocalamus longiauritus leaves. The oil of Cinnamomum cassia showed the best property, and the EC50 against C. mandshurica, G. sanbinetti, and B. cinerea were 0.478μL/mL,0.261 μL/mL and 0.369μL/mL. The oils of Syringa Linn and Melaleuca Alternifolia also had a good inhibitory effect against 3 kinds of fungus. Activity of the oil from Indocalamus longiauritus against 3 kinds of fungus were not obvious, in 3 kinds of fungus, ability of the oil against G. sanbinetti was the best, which with the EC50 was 577.4μL/mL.5. The constituents of the oil from Cinnamomum cassia, Syringa Linn, Melaleuca Ahemifolia and the oil from Indocalamus longiauritus leaves were analyzed by GC-MS.53 compounds of oil from Indocalamus longiauritus which accounting for 70.35% were identified, the main components of the oil were n-Hexadecanoic acid (20.84%),2-Hexenal, (E)-(6.84%), Naphthalene, 1,2,3,4-tetrahydro-1,1,6-trimethyl-(3.79%), and beta-Damascenone (2.16%), et al. The main components of the Cinnamomum cassia oil were Isopropyl Myristate (74.64%), Phenol, 2,2’-methylenebis[6-(1,1-dimethylethyl)-4-methyl-(4.76%),2-Propenal,3-phenyl-(4.68%) and 5.alpha.,8.alpha.,14.beta.-Cholestane (1.11%), et al. And the main components of Syringa Linn oil were Isopropyl Myristate (81.23%), Phenol,2-methoxy-3-(2-propenyl)-(6.62%), Phenol,2,2’-methylenebis[6-(1,1-dimethylethyl)-4-methyl-(1.77%) and Caryophyllene (1.64%), et al. And the main of Melaleuca Alternifolia oil were Isopropyl Myristate (50.35%),3-Cyclohexen-1-ol,4-methy1-1-(1-methylethyl)-, (R)-(13.12%), Eucalyptol (8.34%),1,4-Cyclohexadiene, 1-methyl-4-(1-methylethyl)-(6.94%), and Phenol,2,2’-methylenebis[6-(1,1-dimethylethyl)-4-methyl-(2.377%), et al.