| Jasmine is a typical"temperament flower",which is the raw material for jasmine tea and essential oils.Jasmine tea is a unique reprocessed tea,and has great market potential in China and Southeast Asian countries.There are still some limitations in the research on the opening process of jasmine,the scenting process of jasmine tea and its antidepressant mechanism at this stage:Scholars had explored the molecular mechanism of the aroma release of jasmine in vivo,while the molecular mechanism of the aroma release of jasmine in vitro needs to be further completed.The extraction methods of the essential oil include simultaneous distillation extraction,solvent extraction,etc.,which have problems such as low yield,low purity,and long time.Traditional jasmine tea scenting processing had some disadvantages,such as long production cycle,high labor intensity,low utilization rate of jasmine,and restrictions on seasons and origins,and seriously restricted the further development of jasmine tea industry.Scholars have studied the antidepressant effect of jasmine tea based on neurotransmitters.However,the pathogenesis of depression involved in many aspects,the mechanism of jasmine tea amliorating depression needs to be further completed.The main contents and results of this research were as follows:（1）High-throughput sequencing technology and metabolomics were used to analyze the changes of transcriptional regulation and metabolism during the opening process of jasmine（Qinglei S0,Bailei S1,Huzhao S2,Bankai S3,Quankai S4）,and RT-q PCR and enzyme-linked immunosorbent assays were used to reveal the effects of temperature and time on terpenoids and benzene during the opening process,which can provide a theoretical basis for scenting jasmine tea and essential oil extraction.A total of 39.6 Gb Clean Base was obtained for the eukaryotic unparameterized transcriptome,and the percentage of Q30 bases was higher than 94%.After assembly,a total of197,379 Unigenes were obtained.The functional annotation of the Unigenes was performed,and a total of 197,379 annotation results were obtained.S0 vs.S1,S1 vs.S2,S2 vs.S3,S3 vs.S4 identified 14497,21403,449,and 21136 differentially expressed genes,respectively.A total of 220 compounds were idenfified by extensive non-targeted metabolomics.Using multivariate statistical analysis,an OPLS-DA model was established to analyze the specific metabolites of jasmine during different opening degrees,and finally 26 potential differential metabolites（VIP>1.5,P<0.05）were identified as the metabolites that distinguish jasmine during five stages.The gene expression and enzyme activity of HMGR,FPPS,PAL and SAMT in the synthesis pathways of terpenoids and phenylpropanoids increased with the increase of temperature,while it showed a downward trend accompanied with the increase of temperature after reaching the highest value.Combined with the sensory evaluation results,it was found that the quality of jasmine at 2:00 am at 25°C was better,with strong and fresh fragrance.（2）Using the dried jasmine buds as raw materials,the process of supercritical extraction of essential oil was studied.The effects of the amount of entrainer,raw material particles,pressure,temperature and time on the extraction process were investigated by single factor experiments.The process parameters were optimized by response surface methodology.The optimal process parameters of supercritical CO2extraction of essential oil:the amount of entrainer was 0.2 m L/g,the pollen particle was40 mesh,the extraction pressure was 20 MPa,the extraction temperature was 46℃,and the dynamic extraction time was 1.6 h.Under these conditions,the crude extraction rate of jasmine essential oil was 13.67%,which was much higher than that of simultaneous distillation extraction（2.87%）and ultrasonic-assisted extraction（2.45%）.The main aroma components in essential oil were basically the same as those of jasmine,which has good ability to scavenge free radicals and reduce iron ions.（3）Using jasmine essential oil as raw material,the process parameters of jasmine tea were optimized.Single factor experiment was used to investigate the effect of essential oil addition method,addition amount,time,temperature and the water content of tea dhool on the quality of jasmine tea.On this basis,the process parameters were optimized by response surface methodology.The optimum process parameters for jasmine tea scented by essential oil:the addition amount was 3.75 m L/kg with filter paper,scenting time was 10 days,scenting temperature was 15℃,and the water content of tea dhool was 6%.The quality of jasmine tea produced under this condition was better.（4）Using the internationally recognized chronic unpredictable mild stress（CUMS）model,sugar water preference,open field test and forced swimming test were used as behavioral evaluation indicators.The results showed there was a decrease in sugar water preference and activity in the open field test,and a prolonged immobility time in swimming after 4 weeks CUMS stimulation,which indicated that the CUMS-induced depression model was successfully established.At the same time,the above behavioral indicators were significantly improved after intervention with different doses of jasmine tea,low（21.6 mg/kg）and medium（64.8 mg/kg）doses of jasmine tea had better effects.The concentrations of neurotransmitters factors in cerebral cortex,hippocampus and serum were detected by enzyme-linked immunosorbent assay,and the concentrations of SOD,MDA and GSH-Px in serum were determined by multi-function microplate reader.The results showed that the concentrations of 5-HT,DA,BDNF,and GLP-1 in the cerebral cortex and hippocampus of CUMS rats were increased,and IL-1β,IGF-1,IL-6,and IL-6.TNF-αand ACTH,MDA concentrations in serum were decreased after jasmine tea intervention when compared with the model group.These results indicated that jasmine tea could alleviate depression by regulating the levels of neurotransmitters and inflammatory factors,low and medium doses of jasmine tea had better effects.Illumina Miseq high-throughput sequencing was used to sequence the V3-V4hypervariable regions of gut microbiota in feces,and the effects of different treatments on gut microbiota were compared via gut microbial diversity and composition.The alpha diversity index indicated that CUMS treatment reduced the diversity and richness of gut microbiota.β-diversity analysis showed that there were differences in the distribution of intestinal flora in CUMS rats when compared with the control group,with an increase in the abundance of Firmicutes and a decrease in the abundance of Bacteroides.Jasmine tea intervention increased the diversity and richness of intestinal microorganisms in CUMS rats,and alleviated the intestinal microbial imbalance induced by CUMS.Spearman correlation analysis showed there was an association between gut microbiota and depression.Combined with the predictive analysis of gut microbiota function,those results revealed that jasmine tea may ameliorate the intestinal microflora of CUMS rats mainly through metabolism,genetic information processing,environmental information processing.（5）The effect and mechanism of L-theanine,EGCG and jasmine tea in ameliorating depressive symptoms induced by CUMS were further compared from the perspectives of behavior,biochemical indicators,gut microbiota and metabolomics.The results indicated that the body weight gain,daily diet,sugar water preference,and activity in the open field test were significantly decreased,and the immobility time in forced swimming was significantly prolonged when compared with control group after8 weeks of CUMS stimulation.The intervention of jasmine tea,L-theanine and EGCG improved the above behavioral indicators and ameliorated the symptoms of depression, and the effect of jasmine tea was the best.Enzyme-linked immunosorbent assay was used to detect the contents of neurotransmitters and inflammatory factors in cerebral cortex,hippocampus,colon and serum.The results showed that the intervention of jasmine tea,L-theanine and EGCG increased the contents of 5-HT and BDNF,reduced the levels of TNF-α,NF-k B in CUMS rats;and and the effect of jasmine tea was the best.It was found that the intervention of jasmine tea,L-theanine,and EGCG increased the richness and diversity of gut microbiota in CUMS rats through Illumina Miseq high-throughput sequencing,which were consistent with the results in Chapter 5.The effects of jasmine tea,L-theanine and EGCG in alleviating serum metabolites in CUMS-depressed rats were analyzed by extensive non-targeted metabolomics.A total of 628 and 343 compounds were identified in positive and negative ion modes,respectively.Using multivariate statistical analysis,an OPLS-DA model was established to analyze the serum metabolites in CUMS rats after jasmine tea,L-theanine and EGCG intervention.In positive and negative ion modes,21 and 17 potential differential metabolites were identified（VIP>2,P<0.05）as a metabolite to differentiate CUMS rats,respectively.These differential metabolites were mainly enriched through pathways such as vitamin B6 metabolism,histidine metabolism,glyoxylate and dicarboxylic acid metabolism,and citric acid cycle（TCA cycle）.The results of this chapter indicated that the effect of jasmine tea in ameliorating CUMS depression was better than that of L-theanine and EGCG,which could provide support for promoting the development of the country’s jasmine tea industry. |
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