| Scutellaria baicalensis Georgi is a precious resource of traditional Chinese medicine.It is mainly used as medicine by root.In addition,flavonoids are the main components of its medicinal function.In this work,the components of Scutellaria baicalensis Georgi were analyzed,and the functional components were extracted,transformed and utilized.(1)HPLC and LC-MS were used to analyze and identify the flavonoids and transformed products in the roots and the combination of stems and leaves of Scutellaria baicalensis Georgi.The results showed that the main flavonoids in the roots were baicalin and baicalein,and the contents were 51.3 mg/g(5.13%)and 3.97mg/g(0.40%)respectively.Moreover,in the stems and leaves,scutellarin(3.23%)and baicalin(2.36%),baicalein,scutellarin,chrysin,luteolin,apigenin,8-hydroxyapigenin and other flavonoids were identified.The difference of chemical components in roots and stems and leaves was beneficial to the utilization.(2)Chemical transformation: because aglycones often have better functions than glycosides,in this work,the glycosides in Scutellaria baicalensis Georgi were transformed into aglycones by acid hydrolysis,functional microbial transformation and endogenous enzyme transformation.Acid hydrolysis were performed as follow:20 g of sulfuric acid(98% w/w)was added to baicalin powder(2 g),and 20 m L of water was added immediately(baicalin content in the system was 5%).The results indicated that the initial temperature of the reaction was 40?,the reaction temperature increased to 70? after adding water,and the conversion rate of baicalin was 98.3% and 51.6% after 15 minutes of continuous hydrolysis.(3)Microbial transformation: The transformation of baicalin and scutellarin from Scutellaria baicalensis Georgi roots,and the combination of stems and leaves by Aspergillus niger was studied.The influence factors(temperature,p H,enzyme concentration and culture time)were monitored.The results showed that the conversion rate of baicalin was 89.5% and the yield of baicalein was 85.8% when solid state fermentation of Aspergillus niger for 4 days and the 2% baicalin solution was transformed at p H 5.0 and 55? for 10 h.The results of transformation of scutellarin from stems and leaves revealed that after solid state fermentation for 5days under the condition of p H 5.0,55?,the enzyme solution(solid koji: extraction solution = 1:5)was transformed into the stems and leaves extract with 2.15%scutellarin and 1.57% baicalin for 24 h.The conversion rate of baicalin and scutellarin was 95.0% and 95.3%,respectively.(4)Endogenous enzyme transformation: under the conditions of solid-liquid ratio of 1:25,p H 5.0 and 40?,1 g endogenous enzyme was extracted from the roots of Scutellaria baicalensis Georgi,which was not inactivated by high temperature.2.16 g of the roots extract(including 2 g of baicalin)was transformed by the extracted enzyme solution for 10 h.The conversion rate of baicalin was 95.6%,and baicalein1.00 g(yield 86.1%)was obtained.Compared with direct acid-splitting method and microbial enzyme conversion method,endogenous enzyme method has the advantages of lower cost,no need of strong acid and enzyme production cost in the process,and it is an environmentally friendly,green and safe effective conversion method.(5)The results indicated that the suitable flavor ratio was determined by fuzzy comprehensive evaluation method(Stevia leaves: Scutellaria stems and leaves= 1:24,5 g tea bag formula: 4.8 g Scutellaria stems and leaves,0.2 g Stevia leaves,brewed with 300 ml boiling water for 15 min).The analysis results showed that the contents of total stevioside,total flavonoids and total phenolic acids in soaking solution were0.11 mg/m L,0.19 mg/m L and 0.207 mg/m L,respectively,accounting for 0.66%,1.14% and 1.24%.The content of 4,5-dicaffeoylquinic acid was the highest(0.123mg/m L),accounting for 59.4% of the total phenolic acids in tea and 0.74% of the dry matter in tea. |
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