Quality Evaluation,Total Polyphenols Extraction And Antioxidant Activity Of Cultivation Bletilla Striata

Bletilla striata（Thunb.Reichb.f.）is a perennial herb,belongs to Orchidaceae,Bletilla,is a traditional Chinese medicine,with a medical history more than 2000 years.It is sweet,bitter,astringent and slightly cold,and belongs to lung,stomach and intestine meridians.It is customary to use its dried tubers as medicine.It contains a variety of natural active ingredients,such as polysaccharides,polyphenols,triterpenes,flavonoids,volatile oils,etc,and have various pharmacological effects,such as hemostasis,antibacterial,antitumor,antioxidant,etc.This paper analyzed and evaluated the morphological characteristics,main chemical components and heavy metal contents in cultivated B.striata of different producing areas and different growth periods.The extraction and purification technology of total polyphenols in B.striata tubers,and its in-vitro antioxidant activity were systematically studied.Which laid a theoretical foundation for the breeding of excellent varieties,timely harvest,development and utilization polyphenols resources of B.striata.The results were as follows:（1）There were 7 kinds of cultivated B.striata samples from 4 producing areas.All of which are purple flowers;the color of tuber bud,only HS is purple,the rest is white;the size of bud,CL and YS are giant buds（≥6 cm）,the rest are small buds（≥3 cm）;width of leaf,CL and YS are wide blade profile（≥10 cm）,the rest are narrow blade（≤6 cm）;in addition,there are also significant differences in density of root,thickness of tuber and other forms.The spatial growth patterns of tubers included"tiled growth type"and"stacked growth type".The fresh weight of total tubers and neonatal tuber are ranked in the top three by HJ,HS and CL.The dry-break rate of total tubers are ranked in the top three by MS,HS and TR,while the neonatal tuber dry-break rate are ranked in the top three by MS,HJ and HS.The tuber drying rate showed a gradually increasing trend with time goes,and the annual change trend was basically the same.The mass size of each part of B.striatat is generally showed:tuber>leaf>root;the mass size of tubers of different ages is generally showed:neonatal tuber>2-year-old tuber>3-year-old tuber.the neonatal tuber usually occupied about 60%of the total mass of tuber.The root-shoot ratio is ranged from 323%to 614%in 7 kinds samples,The root-shoot ratio changes periodically in annual growth process,"slow growth in the first half of the year,rapid growth in the second half"conformed to the growth characteristics of herbaceous for many years.（2）The contents of water-soluble protein is highest in HJ,is 3.53%;total phenols and total flavonoids are highest in MS,are 0.72%and 0.80%respectively;starch is highest in HJ,is 54.85%;polysaccharide is highest in HS,is 34.78%;alcohol-soluble protein is highest in YS,is 8.25%,in neonatal tuber of 7 kinds cultivated B.striata from different producing areas.The order of polysaccharide content in tubers of different ages is:neonatal tuber>2-year-old tuber>3-year-old tuber,and the order of alcohol-soluble protein content is:3-year-old tuber>2-year-old tuber>neonatal tuber.The polysaccharide content is highest in HS,is 9.67%,and the alcohol-soluble protein content is highest in MS,is 23.25%,in fibrous roots of 7 kinds samples.The contents of polysaccharide and other main components in cultivated B.striata varied greatly in different growth periods,and starch content was higher in August and September,water-soluble protein content was higher in April and September,polysaccharide content was higher in October of each year,total phenols content was higher in April and May,and total flavones content was higher in April,May and September of each year.In the heavy metal contents of 7 samples,Hg,Cd and Cu did not exceed the standard,Pb is all exceeded the standard,HJ and ZJ As exceeded the standard.In the neonatal tuber of B.striata,the alcohol-soluble protein was significantly positively correlated with total phenols,total flavones and total polyphenols among the main components including polysaccharide;There was a significant positive correlation between total phosphorus and water-soluble protein,available phosphorus and water-soluble protein among the surface soil fertility of the planting land and main components including polysaccharide;There was no significant correlation between the altitude of the producing area and the six components;There was a significant positive correlation between Cd and other 4 kinds heavy metal contents There was no significant correlation between the contents of 4 kinds heavy metal in B.striata and the surface soil of the planting site.（3）Using single factor experiment and response surface methodology,the flash extraction process of total polyphenols in B.striata tubers were optimized as follows:41%ethanol,liquid-solid ratio is 43:1,extraction voltage is 130 V,extraction time is 90s,and the extraction amount is 4.79±0.14 mg/g;The static adsorption and desorption properties on total polyphenols of 10 kinds macroporous resins for B.striata total polyphenols extract,LSA-21 resin was selected by its comprehensive purification effect.The LSA-21 resin dynamic adsorption optimization test showed that the process parameters for purifying B.striata total phenol were as follows:adsorption with the pH value is 4,mass concentration range from 0.4 to 0.6 mg/mL,flow rate is 2.0 mL/min;desorption with the pH value is 6,the ethanol volume fraction is 80%,and the elution flow rate is 1.0 mL/min.The content of B.striata total phenol is increased from 4.48%to 27.61%by dynamic adsorption and desorption verification with 100 mL of crude total phenol extract with a mass concentration of 0.47 mg/mL.Taking Vc as a reference,total antioxidant capacity,DPPH·,OH·and O₂^-·free radical scavenging capacity of B.striata total polyphenols were investigated.The results showed that the mass concentration of total polyphenols increased linearly with the scavenging rate of three kind free radicals and total antioxidant capacity within the experimental design range.DPPH·free radicals,OH·free radicals and O₂^-·of crude extract total polyphenols IC₅₀0 are 10.48,2.23 and 153.83μg/mL respectively;and purified total polyphenols IC₅₀0 are 7.72,8.65 and 205.39μg/mL respectively.