Extraction And Refining Of The Essential Oil From Cinnamomum Camphora(L.)Presl

Cinnamomum camphora?L.?Presl,an important economic and urban greening tree species,is widely distributed in the south of the Yangtze River in China.Every year,a large number of branches and leaves will be produced,but the utilization of resources is very low.According to the previous studies,the essential oil from C.camphora leaves has various bioactive properties,such as antimicrobial,antioxidant,insecticidal and anti-inflammatory activities,which are widely used for chemicals,medicine,food flavoring and fragrances and perfume industries.Although the extraction of essential oil has been studied,the relevant studies were mostly limited to the traditional techniques,and there was little information about the refining,weakening the commercial value of the oil.Therefore,a new green solvent,CO₂-expanded ethanol?CXE?,was used to extract essential oil from C.camphora leaves.The chemical composition of the essential oil was identified by Gas Chromatography-Mass Spectrometry?GC-MS?,and the antioxidant activity and antimicrobial activity of the oil were determined,accordingly compared with that of hydrodistillation extraction?HD?,organic solvent extraction?OSE?and supercritical carbon dioxide extraction?SFE?.Molecular distillation was used for the purification of C.camphora essential oil,and the operation parameters were adjusted,combined with the components analysis of each obtained fraction to find the suitable conditions.Then,the antimicrobial activity and antioxidant activity of each fraction were investigated,and the effect of enriched active components was analyzed to evaluate the feasibility of refining C.camphora essential oil by molecular distillation.The major results were as follows:?1?The traditional methods were used to extract the essential oil from C.camphora leaves,and the properties and chemical composition of the oils were analyzed.The results showed that the yield of oil extracted by hydrodistillation was 1.73%at the conditions including the sodium chloride concentration of 3%,ratio of liquid to solid of 1:4 and distillation time of 60 min.The yield of oil extracted by ether was 1.62%.After analyzing the characteristic aroma of these oils,it was found that the aroma odor of oil extracted by hydrodistillation was strong,while the ether-extracted oil was light,at the same time,a small amount of ether remained.The chemical composition of C.camphora essential oil extracted by these two methods was analyzed by GC-MS,and the main components were 1,8-cineole,linalool and terpineol.?2?A novel green solvent,CXE,was employed to extract essential oil from C.camphora leaves,at the same time,the C.camphora essential oil was also extracted by SFE,a conventional green solvent.The yields of these two oils were 1.35%and 1.14%,respectively.Compared with other three methods,the yield of CXE oil was slightly lower than HD oil and OSE oil,but higher than SFE oil,and the character of the CXE oil were similar to the HD oil and superior to the oils obtained by OSE and SFE.The chemical composition from GC-MS analysis showed that the content of oxygenated monoterpenoids in CXE oil was lower,while the content of sesquiterpene hydrocarbons was higher than oils from other three methods.The DPPH radical scavenging rate and ABTS radical scavenging rate of CXE oil were 82.42%and 85.88%,respectively,presenting a significantly highest activity in contrast to other samples.Additionally,the CXE oil exhibited a prominent ability against two fungi,with the minimum inhibitory concentrations?MIC?of Candida albicans and Aspergillus niger were 312.5 g/m L and 19.5 g/mL,respectively.?3?A two-stage molecular distillation was designed for the refinement of C.camphora essential oil?crude oil?.The components of the oil were enriched by adjusting the evaporation indensity?evaporator temperature and system pressure?and the condenser temperature,and combining with the components analysis of each fraction.In the first stage,the appropriate evaporation intensity was obtained when the evaporator temperature was60°C and the system pressure was 100 Pa,and then the condenser temperature was adjusted.At the temperature of 20°C,the recoveries of heavy residue?1R_H?,middle distillate?1D_M?and light distillate?1D_L?were 13.79%,71.93%and 10.17%,respectively.Moreover,the concentration ratios of methyl heptenone and 1,8-cineole in 1D_L were as high as 5.72 and5.16,respectively.The second stage was carried out on the 1D_L with significantly increased antibacterial activity and the 1R_H with obviously enhanced antioxidant activity,respectively.The contents of methyl heptenone and 1,8-cineole in 2D_L were further increased from 8.57%and 17.81%to 14.42%and 36.62%,respectively,and the overall concentration ratios were9.63 and 10.61.Furthermore,the contents of?-terpineol and?-terpineol in 2R_H were also increased from 39.63%and 10.30%of the crude oil to 53.82%and 14.56%,respectively.?4?The antimicrobial activity of the crude oil and its fractions was determined by microdilution method.After first stage,the antibacterial activity of 1D_L against Staphylococcus aureus and Bacillus subtilis increased from weak level of the crude oil?MIC=625?g/m L?to medium-high level?MIC=78?g/mL?.The inhibitory activity of both 1D_Mand 1D_L against Escherichia coli increased from weak level to medium level?MIC=312.5?g/m L?.In addition,the antifungal activity of 1D_L against Aspergillus niger and Candida albicans was also slightly increased.After second stage,the antibacterial activity of 2D_L against S.aureus was further increased to high level?MIC=19.5 g/m L?.The analysis of chemical composition and antibacterial process indicated that the inhibition of C.camphora essential oil against the test strains might be mainly related to 1,8-cineole and linalool.After the enrichment of these components by molecular distillation,the antibacterial effect of the oil was enhanced.?5?The antioxidant activity of the crude oil and its fractions was investigated by measuring the free-radical scavenging rate.After the two-stage molecular distillation,the scavenging rate of DPPH radical and ABTS radical of 1R_H was 49.57%and 91.75%,respectively,which was increased by 62%and 70%of the crude oil,and the ability of 2R_H was further improved with the scavenging rate of 68.13%and 98.47%respectively.Combined with the composition analysis of each fraction,the scavenging rate of DPPH radical and ABTS radical of the C.camphora essential oil could have a correlation with terpineol.After molecular distillation,these components were mainly enriched in heavy residue,thus improving the antioxidant activity.In conclusion,the CXE extraction can be used to obtain the high quality C.camphora essential oil,especially suitable for the separation of components which are sensitive to the high temperature and oxygen.Therefore,it has the potential to be developed as a promising alternative for the extraction of high-quality plant essential oil.In addition,using a two-stage molecular distillation,the antimicrobial and antioxidant components of the C.camphora essential oil can be successfully enriched.It shows that the molecular distillation can be considered as a potential and promising technique for refining the C.camphora essential oil and for improving the properties of essential oil products.