Chemical Composition And Antimicrobial Activity Of Essential Oil Of Flos Sophorae Immaturus

Flos Sophorae Immaturus are buds of Sophora japonica L.. Recently studies published by medical researchers revealed that the effective components of Flos Sophorae Immaturus have lots of beneficial activities, such as anticancer, antiplatelet aggregation, analgesic effect, antimicrobial, antiviral, antiaging, anti-inflammatory, anti-allergic, anti-free radical, and antioxidation amongst others. Flos Sophorae Immaturus have satisfactory effects in improving myocardial cycle, clearing heat and detoxication, reducing blood lipid, softening blood vessel, diminishing inflammation and nourishing the kidney without side-effects such as lethal, carcinogenesis, teratogenicity or mutation.In this thesis, gas chromatography-mass spectrometer (GC-MS) was applied to analyse the chemical constituents of essential oil from Flos Sophorae Immaturus obtained by the methods of steam distillation and simultaneous distillation extraction (SDE). The results showed that 52 compounds were separated from the essential oil, 43 compounds were identified by SDE and they accounted for 96.54% of the total peak areas. But only 41 compounds were separated from essential oil, 28 compounds were identified by steam distillation and they accounted for 84.53 % of the total peak areas.Different methods, such as Agar diffusion assay, turbidimetric assay and inhibition curves were used to investigate the antimicrobial activity. The results indicated that the essential oil showed obvious antimicrobial actions against Staphylococcus aureus, Escherichia coli, Shigella dysenteriae, Salmonella typhi, Listeria monocytogenes, Listeria welshimeri. But it was not effective against Aspergillus niger and Candida albicans. The minimum inhibition concentrations(MIC) determined by double-dilution method were 0.39μL/mL for Staphylococcus aureus and Listeria monocytogenes, 0.78μL/mL for Listeria welshimeri and Salmonella typhi, 1.56μL/mL for Shigella dysenteria, and more than 25μL/mL for Escherichia coli, Streptococcus haemolyc and Salmonella paratyphi A respectively.Different levels of stressed cells of Staphylococcus aureus was obtained by heat, acid, osmotic pressure, potassium sorbate, sodium benzoate stresses and then the stressed cells were treated by essential oil of Flos Sophorae Immaturus in advance. We found that stressed cells by potassium sorbate were more sensitive to the essential oil. This indicated that essential oil can replace potassium sorbate as a hurdle factor inhibiting the growth of pathogens and enhancing food safety during food process.