| Objective:In this study,Jasminum sambac(L.)Aiton was used as the research object to investigate the optimal conditions for enzymatic hydrolysis assisted extraction of essential oil from Jasminum sambac(L.)Aiton,in order to improve the yield of essential oil from Jasminum sambac(L.)Aiton.To establish a fingerprint of the essential oil from Jasminum sambac(L.)Aiton,and compare and analyze the differences in composition between the essential oil obtained by enzymatic hydrolysis and steam distillation.Screening the most sensitive strains to the volatile oil from Jasminum sambac(L.)Aiton,and determining the minimum inhibitory concentration of different batches of Jasminum sambac(L.)Aiton volatile oil.Combining fingerprint and antibacterial efficacy data,the spectral efficiency relationship of antibacterial activity of volatile oil from Jasminum sambac(L.)Aiton was analyzed using gray correlation method and partial least square method.Method:1.Enzymatic hydrolysis assisted steam distillation was used to extract the volatile oil from Jasminum sambac(L.)Aiton,and response surface methodology was used to optimize the enzymatic hydrolysis parameters with the highest yield.2.Determine the volatile oil from multiple batches of Jasminum sambac(L.)Aiton by GC-MS and establish its fingerprint.The differences in composition between the volatile oil extracted from Jasminum sambac(L.)Aiton by enzymatic hydrolysis and that extracted by steam distillation were analyzed.3.The antibacterial activity of the volatile oil from Jasminum sambac(L.)Aiton against Staphylococcus aureus,Escherichia coli,Enterobacter aerogenes,Salmonella typhimurium,Pseudomonas aeruginosa,and Proteus was determined using the bacteriostatic ring method,and the most sensitive strains to the volatile oil from Jasminum sambac(L.)Aiton were selected.4.Microdilution method was used to determine the minimum inhibitory concentration of different batches of jasmine volatile oil against Staphylococcus aureus to obtain antibacterial efficacy data.The effect of jasmine volatile oil on the growth kinetics of Staphylococcus aureus was measured,and the morphological changes of Staphylococcus aureus were observed using transmission electron microscopy.5.Correlate the common peak data of the fingerprint of jasmine volatile oil with the antibacterial activity pharmacodynamic data,and use the gray correlation method and partial least squares method to study the antibacterial activity spectrum effect relationship of jasmine volatile oil,so as to clarify the component groups of jasmine volatile oil that exert antibacterial activity.Result:1.Response surface methodology was used to optimize the optimal process for enzymatic hydrolysis assisted extraction of volatile oil from Jasminum sambac(L.)Aiton:cellulase dosage 105 U/g,enzymatic hydrolysis time 95 min,enzymatic hydrolysis pH 6.1.Under these conditions,the yield of volatile oil was increased by about 40%compared to steam distillation.2.Collect different batches of volatile oil from Jasminum sambac(L.)Aiton to establish their fingerprints,identify 25 common peaks,and identify their specific chemical components through mass spectrometry analysis and literature review.Through GC-MS analysis,the content of aromatic components linalool and benzyl acetate in the enzymolysis volatile oil was 45.44%and 43.87%higher,respectively,and compared to the content before enzymolysis,components such as ethyl benzoate were added,which improved the quality of the volatile oil.3.The bacteriostatic ring diameter of Staphylococcus aureus and Escherichia coli was measured to be 17 mm and 12.5 mm respectively by the bacteriostatic ring method.The bacteriostatic ring diameter of Salmonella typhimurium,Enterobacter aerogenes,and Proteus was less than 10 mm,while Pseudomonas aeruginosa did not exhibit antibacterial activity.Because Staphylococcus aureus is the most sensitive to the volatile oil from Jasminum sambac(L.)Aiton,it has been selected as a bacterial strain for determining its antibacterial activity.4.The minimum inhibitory concentration of volatile oil from Jasminum sambac(L.)Aiton against Staphylococcus aureus in each batch can be measured by microdilution method.Under the intervention of jasmine volatile oil,the logarithmic growth period of the growth curve of Staphylococcus aureus lagged behind,and the growth rate significantly decreased.Through transmission electron microscope observation,it can be seen that under the intervention of j asmine volatile oil,the cell morphology of Staphylococcus aureus shrinks,the surface of the cell membrane is rough,the distribution of cytoplasm is uneven,and some cells have cell membrane rupture or dissolution,which indicates that jasmine volatile oil may achieve antibacterial effect by destroying the cell membrane of the bacteria.5.The spectrum effect relationship of antibacterial activity of volatile oil from Jasminum sambac(L.)Aiton was studied.The 10 peaks with the highest correlation degree were selected by using the gray correlation method as follows:peaks 5,8,14,10,2,9,3,4,1,and 18.The partial least squares method identified the peaks that were positively correlated with antimicrobial activity as peaks 3,7,4,19,21,22,20,17,1,6,16,and 23.The high contribution peaks with VIP values greater than 1 were peaks 8,3,18,7,21,19,17,22,20,4,24,and 23.Based on the results of grey correlation degree and partial least squares regression analysis,the peaks 3 and 4 with high correlation degree,positive correlation with antibacterial activity,and high contribution degree can be satisfied simultaneously.That is,the key components of the volatile oil of Jasminum sambac(L.)Aiton that exert antibacterial activity are peak 3 linalool and peak 4 benzyl acetate.Conclusion:In this paper,the optimal process conditions for enzymatic hydrolysis assisted extraction of volatile oil from Jasminum sambac(L.)Aiton were optimized,and the yield of volatile oil from Jasminum sambac(L.)Aiton was increased by about 40%.A GC-MS fingerprint of the essential oil from Jasminum sambac(L.)Aiton was established.The antibacterial activity of jasmine volatile oil against various bacteria and the MIC value of different batches of jasmine volatile oil against Staphylococcus aureus were determined.A spectral efficiency relationship model for antibacterial activity of volatile oil from Jasminum sambac(L.)Aiton was established using grey correlation degree method and partial least square regression method. |
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