| Flowering Chinese Cabbage,Brassica campestris L.chinensis var.utilis Tsen et Lee,is one of the specialty vegetables in south China and a plant with great development potential.Flavonoids are an important product of plant secondary metabolism,with antioxidant and anti-inflammatory effects,and are known as "plant gold".The human body cannot synthesize flavonoids by itself,but can only ingest them from the outside.Therefore,the active ingredients and content of flavonoids in food are one of the important indicators to determine the intrinsic quality of flavonoids,which is also a research focus.So far,systematic studies on the extraction process,antioxidant activity and variation characteristics of total flavonoids content in different rapeseed germplasm materials have been lacking.In this study,the method of liquid mass spectrometry was used to conduct qualitative and quantitative analysis,separation and purification,antioxidant activity analysis and correlation study with appearance quality of flavonoids in Flowering Chinese cabbage,so as to lay a foundation for breeding new varieties of Flowering Chinese cabbage rich in active substances.Specific research results are as follows:1.Study on the optimization of extraction technology and antioxidant capacity of flavonoids from flowering Chinese cabbageFour flavonoids(more than 20nmol/g)in flowering Chinese cabbage were identified by liquid-mass spectrometry: Isorhamnetin 3-O-glucoside,Baimaside,Hyperoside and Astragalin.The optimal extraction conditions were determined by single factor test and Box-Behnke as follows: ethanol concentration 70.74%,solidliquid ratio 1g:51m L and extraction time 39.07 min.Under this condition,the extraction rate of flavonoids was 1.289%.D101 resin was the best resin for the purification of total flavonoids in flowering Chinese cabbage by static adsorption test,and its static adsorption rate and resolution rate were 80.53% and 86.3%,respectively.The optimal dynamic adsorption and desorption conditions of D101 resin were as follows: initial concentration of flavonoids 0.256mg/m L,elution rate 2 m L/min and elution solvent ethanol concentration 70%.When the concentration of flavonoids was 20-100?g/m L,the scavenging rate of DPPH free radical increased from 35% to 89%,which was lower than that of positive control group(concentration of anticyclic acid was 56%-94%).ABTS radical scavenging rate increased gradually from 34% to 90%.Compared with ascorbic acid(15.5%-65.1%).In conclusion,flavonoids from flowering Chinese cabbage have strong antioxidant activity against ABTS free radical and weak antioxidant activity against DPPH free radical.2.Correlation analysis of total flavonoids in stem of flowering Chinese cabbage with five appearance and quality traits(thickness,height,weight,leaf color,leaf shape index)The results of correlation analysis showed that there was a significant negative correlation between the three appearance quality traits,such as height,thickness and weight,and the total flavonoid content,but there was no significant correlation between leaf color and leaf shape index and the total flavonoid concentration.The results of stepwise regression analysis and path analysis showed that the concentration of total flavonoids in 150 flowering Chinese cabbage varieties had a great correlation with height,which was the main factor affecting the content of total flavonoids in flowering Chinese cabbage.The 150 flowering Chinese cabbage germplasm materials could be divided into two groups by cluster analysis,and the first group could be further divided into two subgroups.The contents of total flavonoids of the first subtype were high,and the three indexes of weight,thickness and height were all at the best level,which were suitable for breeding of high-quality flowering Chinese cabbage varieties.The three indexes of higher content of the second subclass(flavonoids,weight,thickness and eight)also met the general requirements of highquality commercial flowering Chinese cabbage which could be easily promoted and used as germplasm materials to cultivate high-quality flowering Chinese cabbage.In the second category,the values of thickness,weight and height were generally larger,while the content of total flavonoids was lower.In summary,this study firstly conducted qualitative and quantitative analysis of the main flavonoids in flowering Chinese cabbage by HPLC-MS2,and determined the components and contents of four main flavonoids.The extraction and purification process of flavonoids from flowering Chinese cabbage was further optimized and its antioxidant activity was analyzed in vitro.Finally,the correlation between flavonoids content and main appearance and quality traits of flowering Chinese cabbage was determined.It provides important basis for the exploitation of bioactive substance resources of flowering Chinese cabbage. |
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