ABSTRACT
italic>Astragalus is a commonly used Chinese medicinal material in traditional Chinese medicine (TCM), and with the increase of planting area in recent years, the damage of Astragalus root rot has worsened year by year, which seriously affecting its quality and yield. Fusarium oxysporum is one of the main pathogens causing root rot in astragalus. In this study, UPLC-Q-TOF-MS based metabolomic approach combined with multivariate statistical analysis were used to analyze the metabolite changes of Astragalus in response to F. oxysporum infection. The results showed that 62 metabolites in the Astragalus had significant changes after inoculation of F. oxysporum. Polar metabolites included 40 flavonoids, 8 saponins, 2 nucleosides, 1 vitamin, 1 organic acid, 1 amino acid; while lipid metabolites included 3 fatty acids, 1 diradylglycerols, 2 lysophosphatidylcholine, 1 lysophosphatidylglycerol, 1 phosphatidylinositol, 1 sterol lipid. Among these differential metabolites, the relative content of flavonoids, vitamin B2, tryptophan and salicylic acid were increased, while the relative content of saponins were decreased. Correlation analysis showed that the flavonoids were positively correlated with each other, and positively correlated with most lipids, but negatively correlated with most saponins. In addition, studies have shown that F. oxysporum infection is not an influencing factor for the generation of malonyl substitution of flavonoid. This study elucidates the effect of F. oxysporum infection on Astragalus from the perspective of plant metabolism, which provides a basis for exploring the interaction mechanism between the Astragalus and F. oxysporum and further promoting molecular breeding.
ABSTRACT
Root rot severely restricts the sustainable development of Astragalus membranaceus var. mongholicus (AMM) industry. Resistance breeding is an economical and environmentally safe way to manage the disease and its key lies in the obtaining of resistance indicators. This study aimed to quickly and accurately screen the resistance-related (RR) metabolites so as to provide reference for the screening of indicators of AMM breeding for resistance. LC-MS-based targeted metabolomics and real-time quantitative PCR technology were employed, in combination with multivariate statistical analysis, in analyzing the dynamic changes of phenylpropanoid metabolites in AMM in response to root rot pathogen Fusarium solani (FS) infection and identifying the differential metabolites. The LC-MS method established showed high sensitivity; each metabolite had a good linear relationship (R2 ≥ 0.968 9) in the corresponding linear range of the respective standard curve; the recoveries and the relative standard deviations (RSDs) (n = 6) ranged from 70% to 107% and from 1.2% to 9.9%, respectively. Obvious disturbances were observed in the changes of the targeted metabolites in AMM infected by FS. These metabolites, compared with the mock-inoculated (CK) group, showed different up or down regulation with time series. Calycosin-7-O-β-D-glucoside, ononin, calycosin and formononetin were identified as differential metabolites, and they all belong to flavonoids. The first three compounds were significantly negatively correlated (r ≤ -0.97, P < 0.05) with the content of FS in the root of AMM. As potential RR metabolites, they are helpful in obtaining promising resistance indicators for AMM against FS infection.
ABSTRACT
Aging can cause degenerative changes in the function of multiple tissues and organs in the body. Gastrointestinal diseases and intestinal dysfunction are very common in the elderly people. The purpose of this study is to explore the effect of the total extract of Astragalus membranaceus (Fisch.) Bge. on intestinal function and gut microbiota homeostasis in natural aging mice, which will provide clues for further mechanism study. The natural aging mice model is established and animal experiments follow the regulations of the Animal Ethics Committee of Nanjing University of Traditional Chinese Medicine. The overall health of the mice was evaluated by the "frailty index" scoring method. The intestinal absorption and transport function were measured by detecting intestinal glucose absorption capacity, transport time, lipase and amylase activities of aging mice. Intestinal inflammation was assessed by detecting inflammatory cytokines by enzyme-linked immunosorbent assay (ELISA). The pathological changes in the intestines of aging mice were tested by hematoxylin-eosin (H&E) staining and alizarin blue (AB) staining. The qRT-PCR method was used to explore the gene transcription level related with the proliferation and differentiation of intestinal stem cells. Microbiota analysis based on 16S rDNA were used to evaluate the composition of gut microbiota. The results showed that Astragalus had a tendency to reduce the "frailty index" of aging mice, but did not show a significant difference. In some indicators of aging phenotype, Astragalus has the most significant effect on hair loss and physical fitness. In terms of intestinal function, Astragalus could increase intestinal glucose absorption capacity, shorten intestinal transportation time and promote lipase secretion in aging mice. The levels of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) in the aging intestinal tissue were reduced after Astragalus administration. Astragalus also ameliorated the pathological degeneration of the intestinal tissue of aging mice by increasing the length of small intestinal villi, the thickness of colonic mucosa and goblet cell number. In addition, Astragalus elevated the expression of genes associated with the proliferation and differentiation in jejunum and modulated gut microbiota, especially restoring the abundance of Lachnospiraceae. Taken together, the above research results demonstrate the total extract of Astragalus as a key factor improving the intestinal function and gut microbiota homeostasis of aging mice.
ABSTRACT
Seven compounds were isolated from Astragalus membranaceus of northern shaanxi by silica gel and Sephadex LH-20 column chromatographies. Their chemical structures were identified on the basis of their physical and chemical properties. These compounds were elucidated as astragaloside IV (1), formononetin (2), calycosin (3), 1-(4-hydroxyphenyl)-4-(2,4-hydroxyphenyl)-2-hydroxy-1,4-but anedione (4), (E)-4-methylcinnamic acid (5), quercetin (6), and uridine (7). Compound 4 is a new compound and compound 5 was isolated from the plants of Astragalus Linn. for the first time. The results of in vitro antitumor activity assay showed that compound 4 could inhibit the proliferation of A549 with IC50 values of 11.41 μmol·L-1.
ABSTRACT
Molecular mass distribution of Astragalus polysaccharides is wide. Astragalus polysaccharides prepared by conventional water extraction and alcohol precipitation are mostly mixture of macromolecules. Although studies have shown that Astragalus polysaccharides have two-sided immunomodulation, the relationship between anti-inflammatory components and molecular mass distribution of Astragalus polysaccharides is not clear. Therefore, Astragalus polysaccharides were extracted by water extraction and alcohol precipitation. The relative molecular weight of them was determined by high performance gel permeation chromatography (HPGPC). Astragalus polysaccharides with different molecular weights were separated and prepared by membrane separation. RAW 264.7 cells were induced by lipopolysaccharide (LPS) to establish an inflammatory cell model in vitro and the anti-inflammatory polysaccharide were screened. The anti-inflammatory regulation mechanism of Astragalus polysaccharides was analyzed by the LC-MS/MS metabonomics technology. The results showed that APS was composed of APS-Ⅰ ( > 2 000 kDa) and APS-Ⅱ (10 kDa). APS-Ⅰ was composed of mannose, rhamnose, galacturonic acid, glucose, galactose, arabinose and the molar ratios of these monosaccharide of APS-I were 0.54∶0.26∶12.24∶17.24∶8.46∶1. APS-II was composed of rhamnose, galacturonic acid, glucose, galactose, arabinose and the molar ratios of these monosaccharide of APS-II were 0.26∶0.14∶24.04∶0.62∶1. APS-Ⅰ and APS-Ⅱ had no cell toxicity to RAW 264.7 macrophage in the range of 0-100 μg·mL-1. Compared with the model group, APS-I at a concentration of 0-100 μg·mL-1could significantly inhibit the secretion of NO and TNF-α by RAW 264.7, and can significantly promote the secretion of IL-10. APS-I had better anti-inflammatory activity than APS-II in vitro. The metabolomics results showed that 32 different metabolites were found between the model group and blank group; APS-I group can significantly callback 18 different metabolites; mainly related to arginine biosynthesis, arginine and proline metabolism, pyrimidine metabolism, citric acid cycle (TCA cycle), cysteine and methionine acid metabolism, tryptophan metabolism. This study found that APS-I had better anti-inflammatory activity than APS-II in vitro, and its mechanism may be closely related to amino acid metabolism and energy metabolism, which indicated the direction for further clarifying the pharmacodynamic material basis of Astragalus polysaccharides.
ABSTRACT
italic>Astragalus polysaccharides are the main immunomodulatory substances in Astragali Radix. The structure of polysaccharides is difficult to accurately determine, which limits the in-depth study of the molecular mechanism of Astragalus polysaccharides in vivo. "Polysaccharide receptor theory" believes that there are one or more oligosaccharide fragment "active centers" in immunologically active polysaccharide molecules. Therefore, the degradation of Astragalus polysaccharides into oligosaccharides and the study of the active centers of polysaccharides at the oligosaccharide level provide new ideas in the study of the structure and mechanism of Astragalus polysaccharides. This article adopts endo-α-1,4-glucanase enzymatic hydrolysis, and determines the best degradation conditions through single factor test and orthogonal test to degrade the immunologically active polysaccharide APS-Ⅱ (10 kDa component) into oligomers with different degrees of polymerization. Then through the preparation of polyacrylamide gel chromatography and specific immune and non-specific immune cell tests, the immune activity screening of different oligosaccharide components is carried out. The animal welfare and the experimental process in this study follow the requirements of the Animal Ethics Committee of Shanxi University. The results showed that compared with the immunologically active polysaccharide APS-Ⅱ, different oligosaccharide components have obvious differences in different immunological activities. This paper studies the different immunological activities of Astragalus polysaccharides at the level of oligosaccharides, laying a foundation for further elucidating the structure and function of Astragalus polysaccharides, enriching the theory of polysaccharide receptors, and providing new ideas for the development of Astragalus polysaccharides.
ABSTRACT
A quantitative analytical method based on HPLC coupled with the charged aerosol detector (CAD) for quantitative analysis of multi-components with a single marker (QAMS) was established for simultaneous determinations of astragaloside Ⅰ, astragaloside Ⅱ, astragaloside Ⅳ, calycosin-7-O-β-D-glucoside, formononetin and 7,2'-dihydroxy-3',4'-dimethoxyisoflavan in Astragalus membranaceus. The separation was performed on an Agilent SB-C18 (150 mm×4.6 mm, 3.5 μm), with gradient elution using the mobile phase consisting of 0.05% formic acid solution and 0.05% formic acid acetonitrile at the flow rate of 1.0 mL·min-1. The column temperature was 35 ℃, and the injection volume was 20 μL. For CAD, the drift tube temperature was at 50 ℃. The contents of six components in A. membranaceus were determined by both external standard method (ESM) and QAMS, and then were compared. The results showed that chromatographic peaks were separated well and the linear ranges of astragaloside Ⅰ, astragaloside Ⅱ, astragaloside Ⅳ, calycosin-7-glucoside, formononetin and 7,2'-dihydroxy-3',4'-dimethoxyisoflavan were 0.113-2.250 mg·mL-1, 0.012-0.240 mg·mL-1, 0.004-0.080 mg·mL-1, 0.065-1.300 mg·mL-1, 0.005-0.100 mg·mL-1 and 0.007-0.150 mg·mL-1, respectively. The content ranges of astragaloside Ⅰ, astragaloside Ⅱ, astragaloside Ⅳ, calycosin-7-glucoside, formononetin and 7,2'-dihydroxy-3',4'-dimethoxyisoflavan were 0.306-0.922 mg·g-1, 0.053-0.183 mg·g-1, 0.015-0.092 mg·g-1, 0.069-0.823 mg·g-1, 0-0.098 mg·g-1 and 0.020-0.107 mg·g-1 in 20 batches of A. membranaceus, respectively. Using astragaloside Ⅱ as an internal reference, the relative correlation factors of astragaloside Ⅰ, astragaloside Ⅳ, calycosin-7-O-β-D-glucoside, formononetin, and 7,2'-dihydroxy-3',4'-dimethoxyisoflavan were calculated as 0.561, 0.835, 0.299, 0.796, and 0.799, respectively. The results were compared with those obtained by the external standard method to verify the feasibility, rationality and repeatability of QAMS method, and there was no significant difference in assay results between the two methods. In conclusion, the QAMS method is accurate and feasible, and could be used to determine the contents such as astragaloside Ⅰ, astragaloside Ⅱ, astragaloside Ⅳ, calycosin-7-glucoside, formononetin and 7,2'-dihydroxy-3',4'-dimethoxyisoflavan, and it can be used for quality control of A. membranaceus.
ABSTRACT
To effectively identify the Astragalus and its adulterants based on ITS2 sequence and secondary structure, in this study, 32 portions of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Beg.) Hsiao and Astragalus membranaceus (Fisch.) Bge. collected were conducted ITS2 sequence amplification and bidirectional sequencing, whose results were then spliced by CExpress software remove the 5.8S and 28S sequences at both ends to obtain a complete ITS2 sequence. In addition, 3 ITS2 sequences for each of the adulterants of Astragalus, respectively, Oxytropis coerulea, Caragana sinica, Hedysarum polybotrys, Althaea rosea were downloaded from GenBank. The intra-specific and inter-specific genetic distances were calculated by the software MEGA7 to analyze the difference of each sequence; the Neighbor-joining (NJ) method was used to construct the phylogenetic tree based on ITS2 sequence (primary structure) as well as joint ITS2 sequence and its secondary structure. The results showed that the average ITS2 sequence length of both A. mongolicus and A. membranaceus was 216 bp, and their average GC content was 50.00% and 50.46%, respectively. The similarity of ITS2 sequence length and GC content between the two kind of Astragalus and Oxytropis coerulea was the highest, while the ITS2 sequence length and GC content of Althaea rosea showed great differences with those of Astragalus. The inter-specific distance between Astragalus and Oxytropis coerulea was the smallest, while that between the medicinal Astragalus and Hedysarum polybotrys, Caragana sinica as well as Althaea rosea was great. The phylogenetic trees constructed based on the ITS2 sequence (primary structure) and joint ITS2 sequence and its secondary structure showed that the topological relations of the two phylogenetic trees were basically the same, and both could effectively identify the Astragalus and its adulterants. What’s more, the addition of secondary structure information made end branch of the phylogenetic tree become more in its construction, and the distinguish ability and approval rating were also improved, which further reflected the genetic relationship of Astragalus and its adulterants. This provides some scientific basis for classification and accurate identification of Astragalus and its adulterants.