| There are many kinds of tea from all over the world,but the comparative study of teas in the same region was less.The objects of this study were Mallotus oblongifolius Muell.Arg.(MO),Ilex kudincha C.J.Tseng(KD),Camellia sinensis var.Assamica(J.W.Mast.)Kitam.Hainan Dayezhong(DY)and Camellia sinensis(L.)O.Ktze.Hainan Baisha(BS)four Hainan endemic tea varieties,the biological activities of four kinds of tea were compwered and studied.In this study,the chemical constituents of four kinds of tea,as well as their antioxidant activity in vitro and in vivo and bacteriostatic activity were determined to compwere the biological activity of the four kinds of tea.The thesis includes the following parts:1.Four kinds of tea were extracted by decoction method,and the powder of four kinds of tea water extract were obtained,and the total polyphenol content and total flavone content of four kinds of tea water extracts were determined.The content of total polyphenols in the water extract of MO was the highest,which was 420.05±25.65mg GAE/g DW,followed by the water extract of DY,BS and KD,and the content of total flavonoids in the water extract of KD was the highest.It was 691.60±19.47 mg RE/g DW,followed by the water extracts of DY,BS and MO.2.Evaluation of antioxidant activity of four teas by six in vitro antioxidant methods and S.cerevisiae and evaluation of antibacterial activity of tea by five bacteria.The results of six kinds of in vitro antioxidant activity tests were carried out,the order of scavenging DPPH free radicals,ABTS free radicals and high-valent iron ions from strong to weak was:MO>DY>BS>KD;the order of scavenging hydroxyl radicals,superoxide anion and total reducing ability from strong to weak was:DY>MO>BS>KD.Among them,the survival rate of S.cerevisiae was:4 kinds of tea water extracts had certain selectivity to the antioxidant capacity of 5 strains of S.cerevisiae,and the antioxidant activity of KD water extract was the most significant for the gene-deficient strain gsh1?.The antibacterial activities were as follows:4 kinds of tea water extracts had certain selectivity for the inhibition of 5 pathogenic bacteria,and the water extract of DY had the strongest antibacterial activity against Staphylococcus aureus,and its MIC was 1.56 mg/mL.At the same time,MO and KD also had strong antibacterial activity against Staphylococcus aureus,and their MIC were 3.13 mg/mL;in addition,MO had strong antibacterial activity against the other four pathogenic bacteria,and their MIC were 6.25 mg/mL,the antibacterial activity of MO was broader.3.Four types of tea extracts were subjected to macroporous resin column chromatography and silica gel column chromatography to obtain four kinds of resin extracts and eight chromatograms,respectively.In this experiment,the total polyphenol content and total flavonoid content of their components were determined,and their antioxidant activities in vitro were determined by EPR technique.Among them,DY-fraction II had the highest total polyphenol content of 669.55±4.74 mg GAE/g DW;DY-fraction I had the highest total flavonoid content,which was 974.22±5.31 mg RE/g DW;The strongest free radical scavenging rate of DPPH was DY-fraction II,its IC50 was 4.13±0.70 ?g/mL,BS-fraction I had the strongest hydroxyl radical scavenging rate,and its IC50 was 0.63±0.17 ?g/mL,both of which were stronger than positive control ferulic acid.4.Two fractions of the four teas were subjected to component analysis by UPLC-PDA-ESI-(-)-HRMS and the active compounds were identified.In MO,it had 14 compounds identified,and the top three compounds with the highest content were quercetin,1-O-gallicacid-6-O-lutein-a-glucose and kaempferol-3-O-inosine.15 kinds of compounds were identified in KD,and the first three compounds with the highest content were 4,5-dicaffeyl quinic acid and 3,5-dicaffeoyl quinic acid and 3,4-dicaffeoylquinic acid.16 kinds of compounds were identified in DY,the highest content of the first three compounds were caffeine,epicatechin gallate and epicatechin;In BS,it identified 16 compounds,of which the top three compounds were caffeine,epigallocatechin gallate and epicatechin gallate.5.The wild type S.cerevisiae(WT)and the gene-deficient S.cerevisiue(sodl?)under H2O2 stress were used as biological models and the protective effects of four teas on yeast cells were tested.Among them,MO reduced intracellular oxidation level,increased catalase activity,glutathione reductase activity,reduced glutathione and oxidized glutathione content.KD had the strongest effect on increasing cell viability and reducing cell lipid peroxidation rate.DY had the best effect on the activity of superoxide dismutase.BS had the highest activity in the halo test,and the POD activity of the two were the strongest.6.The antioxidant activities of the four teas were determined by using the cellular antioxidant activity assay(CAA)method.The result of their activity from strong to weak were:MO>DY>BS>KD.The results were related to quercetin,the highest content compound of MO.and the activity of DY was higher than that of BS,and the contents of epicatechin gallic acid and epicatechin in DY were higher than that of BS.The antioxidant activity of dicoffee acyl quinic acid was lower than that of the first three.Therefore,by comprehensive analysis of the biological activities of the four teas,it can be seen that all four teas had strong antioxidant activity,of which the antioxidant activity of MO was the strongest,followed by DY,BS and KD.At the same time,DY had the strongest antibacterial activity against Staphylococcus aureus;while MO had a broad spectrum of antibacterial activity.This conclusion can be used as a scientific basis for the development and utilization of potential natural antioxidants. |
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