| In recent decades,with the increasing demand for Astragali Radix,it is difficult to maintain wild resources,and the cultivated Astragali Radix has become the mainstream of medicine.At present,the main production areas of Astragali Radix have different production methods,which can be basically divided into two types,namely,the fast-growing Astragali Radix(FGA)transplanted after seedling cultivation and the imitate wild Astragali Radix(IWA)whose seeds have been broadcast for 5～6 years or more.The standard T/CACM 1021.4-2018 of Astragali Radix commodity specification and grade issued and implemented by the China Association of Chinese Medicine in 2018 divided the current popular Astragalus commodity into FGA and IWA according to the cultivation mode.There are obvious differences in the appearance properties of the two different specifications of Astragali Radix.The real estate areas represented by Datong,Xinzhou in Shanxi Province and Zizhou in Shaanxi Province are the imitation of the wild planting mode.The produced IWA is consistent with the core characteristics of high-quality Astragali Radix as summarized by Bencao Mengquan in the literature of the past dynasties,that is,"the single strand with no branch,straight as an arrow,the skin color is brown,the meat is white and the heart is yellow,it is soft like cotton,and chews sweet as honey".However,the characters of FGA in Gansu and Inner Mongolia are not consistent with those of traditional high-quality Astragali Radix recorded in historical documents.Based on this,it is necessary to do further in-depth research on two different specifications of Astragali Radix by means of traditional characteristics and modern analytical techniques,so as to provide a scientific basis for scientifically revising the commodity specification and grade standards of Astragali Radix and guiding the high-quality production of Astragali Radix.In this study,guided by the idea of distinguishing the appearance and quality,the two different specifications of Astragali Radix were systematically compared and analyzed from the aspects of macro properties,micro characteristics and chemical composition.Modern analytical techniques such as LC-MS and MSI were used to study the differences and relationships between the two at different levels.This study is divided into five chapters.The first chapter summarizes the current research on the chemical constituents and pharmacology of Astragali Radix.On this basis,it summarizes the relevant quality research carried out in the past 30 years,and puts forward the further research direction of this subject on the basis of sorting out and analyzing the research status.In the second chapter,the appearance characters,length and diameter of two different specifications of Astragali Radix were compared and analyzed.The results showed that the IWA was long and straight,with fewer lateral roots,loose organization and tough skin.The periderm was rougher than that of FGA.The cuticular laye was brown,the cross-section wood core was bright yellow,and the outer skin was white.The color contrast between yellow and white was obvious.The characters of IWA are similar to those of high quality Astragali Radix recorded in Bencao Mengquan.There are many lateral roots at the lower end of FGA,with solid texture,sufficient powder,relatively smooth and thin outer skin,light yellow xylem at the section,no obvious contrast with phloem color,and great difference from the traditional high-quality Astragali Radix recorded in the literature.The length and diameter of the two species were measured and statistically analyzed.The results showed that the length and diameter of IWA produced in Shanxi and Shaanxi increased with the growth years,and there was a significant positive correlation.The body length of IWA in Shaanxi Province was 88～130 cm in 6 years,and that in Shanxi Province was 50～130 cm in 5 years;The body length of FGA is relatively stable,ranging from 40 to 60 cm.The ratio of the upper diameter to the lower diameter of IWA in Shaanxi can reach 5.98,the ratio of the upper diameter to the lower diameter of IWA in Shanxi can reach 6.69,while that of FGA in Gansu can only reach 3.55.It shows that the FGA produced by horizontal planting method in Gansu and Inner Mongolia is symmetrical.In the third chapter,the paraffin sections of IWA and FGA were made,and their microstructures were compared.The results showed that there were obvious cracks in the tissues of the IWA,the arrangement of wood rays and phloem rays was loose,the number of wood fiber bundles was small,and the macroscopic texture was soft and tough.The conduits are arranged in bundles of three or two,arranged in concentric rings,which are macroscopically reflected as concentric ring-shaped growth rings visible to the naked eye in the cross section.The number of periderm cells was significantly more than that of FGA.Stone cells were found in the cork layer,and thick horn cells were found in the cork inner layer.Macroscopically,the epidermis of IWA is thicker and coarser than that of FGA.With the increase of growth years,the number of annular growth rings increased,the cracks between tissues became more obvious,and the number of cell layers in cork layer and cork inner layer decreased.FGA has fewer tissue fissures,closely arranged wood rays and phloem rays,more wood fiber bundles,fewer cell layers of cork layer and cork inner layer than that of IWA,and no stone cells.Macroscopically,the texture of FGA is solid,and the epidermis is is thin and tender.In the fourth chapter,based on the characteristics of traditional Astragali Radix "folding soft like cotton" and "chewing sweet as honey",the two specifications of Astragali Radix are compared and analyzed.The IWA conforms to the characteristics of soft and resilient texture recorded in the tradition.The FGA has a solid texture,sufficient powder,and tastes sweeter than the FGA.In this chapter,the content of the components that may cause the difference was determined.Based on the principle of "anthrone colorimetry" and to the determination method of Polygonatum Polysaccharide in Chinese Pharmacopoeia,the content of polysaccharide was determined and compared;According to the general principles of extracts in Chinese Pharmacopoeia,the content of extract of Astragali Radix in different cultivation modes was determined and compared by using the cold leaching method under the determination method of water-soluble extract(general rule 2201).Referring to the determination method of water-soluble extract of Astragali Radix,the contents of 100%alcohol extract and 80%alcohol extract were determined and compared.The contents of starch and sucrose in different specifications of Astragali Radix were compared with references.The results showed that the contents of polysaccharide,starch and 100%alcohol extract in FGA and IWA were similar,the contents of water extract,80%alcohol extract and sucrose in FGA were significantly higher than those in IWA.This may be the reason why the FGA has a solid texture and tastes sweeter than the IWA.In the fifth chapter,based on the characteristics of "white meat and yellow heart",the two specifications of Astragali Radix were compared and analyzed.The IWA has the characteristics of "white meat and yellow heart",but the FGA does not,which indicates that there are differences in the chemical composition and spatial distribution of their bark and heart.By reference method,with Calycosin as the reference substance,the total flavonoid content of the two was measured and compared by colorimetry;with Astragaloside IV as the reference substance,the classic"vanillic acid-glacial acetic acid",the total saponin content of the two was measured and compared with the perchloric acid colorimetric method.In this study,the chemical constituents of IWA and FGA were analyzed and compared by LC-MS.Firstly,the chemical components of Astragalus were qualitatively analyzed.Through consulting the literature,the database of chemical components of Astragalus plants was constructed.The mass spectrometric cracking laws of the main chemical component standards contained in Astragalus were studied under the condition of UPLC-Q-TOF-MS,and the cracking laws of these compounds were summarized.On this basis,the total ion flow diagram of Astragali Radix in positive and negative ion mode was obtained.According to the accurate relative molecular weight and ion fragment information,and matching with the database established earlier,the chemical components in Astragali Radix were identified.54 flavonoids and 37 saponins were identified,which was consistent with the composition law reported in the literature.The main chemical components of Astragali Radix are flavonoids and saponins.The content of flavonoids is relatively high in the wood core,while saponins are concentrated in the outer skin.In order to further clarify the material basis of the difference between the two specifications of Astragali Radix,two parts of bark and wood were separated in this study,and the differences of chemical components in different parts of IWA and FGA were compared.Principal component analysis(PCA)and orthogonal projections to late structures discriminant analysis(opls-da)were performed on their fingerprints by using Genesis Qi liquid chromatography-mass spectrometry(LC-MS)data analysis software,and representative components contributing to the difference between them(VIP<1)were obtained.The PCA results showed that the data fit well.Through data processing,9 flavonoids were screened from the wood core and 8 saponins were screened from the outer skin.It is considered that these components contribute greatly to the difference between the two.The results showed that the contents of flavonoid glycosides and flavonoid glycosides linked with glucose were relatively high in the heart of FGA,while the contents of monoacyl substituted flavonoid glycosides were higher in the heart of IWA.The content of saponins in the outer skin of IWA was relatively high.Existing literature studies have shown that the changes in the content of components of Astragali Radix are closely related to the growth years.Therefore,the differential compounds obtained in the previous step were used as indicators to explore the content changes of IWA in different years.Quanlynx quantitative software was used to determine the content of different components in IWA grown for 1,2,3,4,5,6,7,11,15,and 17 years.The results showed that the content of these components fluctuated greatly with with the increase of age,the content of flavonoids in the xylem was highest in 5～7 years,saponins in the phloem in the first 4 years,and the increase of the later years had less impact on their content changes.It shows that different components in Astragali Radix accumulate or decrease with the increase of age.At present,the harvest time of IWA is generally about 5～7 years,which is the balance point between production cost,yield and internal quality.In this study,the spatial distribution of chemical components in roots was compared between IWA and FGA in positive and negative ion modes by MSI.The results showed that there were obvious differences between them.Some organic acids(m/z 279.23,m/z 133.0178 in the negative ion mode)were distributed in the cambium of IWA and FGA.The response of IWA was slightly higher than that of FGA,while some sugars(m/z 341.1085,m/z 683.223 in the negative ion mode)in the six-year-old IWA were significantly lower than that of FGA.In this study,the possible material basis of the characteristic of "meat white heart yellow"was further explored.The bright yellow woody core of IWA was extracted,and the yellow components were separated and purified by column chromatography and liquid phase preparation.A yellow powder soluble in methanol was obtained.The chemical structure of the compound was identified as sulfuretin by MS and nuclear magnetic resonance(NMR).It was speculated that the compound was one of the components that contributed to the bright yellow xylem of Astragali Radix.This substance was first reported in A.membranaceus var.mongholicus.To sum up,this study focused on the traditional traits,compared and analyzed th e two specifications of IWA and FGA from the levels of traits,microscopic and chem ical components,and studied the causes of the characteristics of traditional high-quality Astragali Radix from different levels.At the same time,the new technology of MSI was applied,and the possible substances that make the wood heart yellow in tradition al high-quality Astragali Radix were preliminarily extracted and identified,which provi ded a basis for guiding the scientific production and quality evaluation of Astragali Ra dix. |
PDF Full Text Request