Triterpene and Flavonoid Biosynthesis and Metabolic Profiling of Hairy Roots, Adventitious Roots, and Seedling Roots of Astragalus membranaceus

Progress on metabolites of Astragalus medicinal plants and a new factor affecting their formation: Biotransformation of endophytic fungi

It is generally believed that the main influencing factors of plant metabolism are genetic and environmental factors. However, the transformation and catalysis of metabolic intermediates by endophytic fungi have become a new factor and resource attracting attention in recent years. There are over 2000 precious plant species in the Astragalus genus. In the past decade, at least 303 high-value metabolites have been isolated from the Astragalus medicinal plants, including 124 saponins, 150 flavonoids, two alkaloids, six sterols, and over 20 other types of compounds. These medicinal plants contain abundant endophytic fungi with unique functions, and nearly 600 endophytic fungi with known identity have been detected, but only about 35 strains belonging to 13 genera have been isolated. Among them, at least four strains affiliated to Penicillium roseopurpureum, Alternaria eureka, Neosartorya hiratsukae, and Camarosporium laburnicola have demonstrated the ability to biotransform four saponin compounds from the Astragalus genus, resulting in the production of 66 new compounds, which have significantly enhanced our understanding of the formation of metabolites in plants of the Astragalus genus. They provide a scientific basis for improving the cultivation quality of Astragalus plants through the modification of dominant fungal endophytes or reshaping the endophytic fungal community. Additionally, they open up new avenues for the discovery of specialized, green, efficient, and sustainable biotransformation pathways for complex pharmaceutical intermediates.

The effect of different LED wavelengths on the components and biosynthesis of isoflavonoid in sprout Astragalus membranaceus

An artificial light source is the optimal element for studying the usability of the medicinal plant Astragalus membranaceus as a sprout vegetable. Based on artificial light source conditions, formononetin (FO) level was the highest (2.6 mg/L) in A. membranaceus exposed to white light emitting diode (LED) light, and calycosin (CA) level was the highest (3.09 mg/L) in the plant exposed to red LED light. According to the publicly available transcriptome data of LED-exposed sprout A. membranaceus LED, reference genes related to the content enhancement of FO, an isoflavone compound, and those related to the content enhancement of CA were selected. The expression patterns of these genes were assayed using qPCR. Among the genes related to FO enhancement, Gene-225190T showed the highest mRNA levels in cells of LED-white light-exposed sprout A. membranaceus; among the genes related to CA enhancement, Gene_042770T showed the highest expression under red LED light. Most genes related to the overall biosynthesis regulation of flavonoids of the upper concept of isoflavone were highly expressed in response to red LED light, and the transcriptional level of 4CL in response to red LED light was the highest. Based on these results, the artificial light sources that regulated the FO and CA contents in sprouts A. membranaceus were white and red LED lights, and the selected reference genes were capable of regulating isoflavone biosynthesis.

Advances in Biotechnological Production and Metabolic Regulation of Astragalus membranaceus

Legume medicinal plants Astragalus membranaceus are widely used in the world and have very important economic value, ecological value, medicinal value, and ornamental value. The bioengineering technology of medicinal plants is used in the protection of endangered species, the rapid propagation of important resources, detoxification, and the improvement of degraded germplasm. Using bioengineering technology can effectively increase the content of secondary metabolites in A. membranaceus and improve the probability of solving the problem of medicinal plant resource shortage. In this review, we focused on biotechnological research into A. membranaceus, such as the latest advances in tissue culture, including callus, adventitious roots, hairy roots, suspension cells, etc., the metabolic regulation of chemical compounds in A. membranaceus, and the research progress on the synthetic biology of astragalosides, including the biosynthesis pathway of astragalosides, microbial transformation of astragalosides, and metabolic engineering of astragalosides. The review also looks forward to the new development trend of medicinal plant biotechnology, hoping to provide a broader development prospect for the in-depth study of medicinal plants.

Advances in the chemical constituents, pharmacological properties and clinical applications of TCM formula Yupingfeng San

Yupingfeng San (YPFS) is a famous and commonly used traditional Chinese medicine (TCM) formula for the treatment of chronic obstructive pulmonary disease, asthma, respiratory tract infections, and pneumonia in China. It is composed of three Chinese herbs, including Astragali Radix, Atractylodis Macrocephalae Rhizoma and Saposhnikoviae Radix. In this review, the relevant references on YPFS were searched in the Web of Science, PubMed, China National Knowledge Infrastructure (CNKI), and other databases. Literatures published from 2000 to 2022 were screened and summarized. The constituents in YPFS could be classified into nine groups according to their structures, including flavonoids, saponins, essential oils, coumarins, lactones, amino acids, organic acids, saccharides, chromones and others. The importance of chemical constituents in YPFS were demonstrated for specific pathological processes including immunoregulatory, anti-inflammatory, anti-tumor and pulmonary diseases. This article systematically reviewed the up-to-date information on its chemical compositions, pharmacology and safety, that could be used as essential data and reference for clinical applications of YPFS.

Antitumor Effect of Cycloastragenol in Colon Cancer Cells via p53 Activation

Colorectal cancer cell (CRC) is the fourth most common cancer in the world. There are several chemotherapy drugs available for its treatment, though they have side effects. Cycloastragenol (CY) is a compound from Astragalus membranaceus (Fisch.) Bge known to be effective in aging, anti-inflammatory, anticancer, and anti-heart failure treatments. Although many studies have demonstrated the functions of CY in cancer cells, no studies have shown the effects of p53 in colon cancer cells. In this study, we found that CY reduces the viability of colon cancer cells in p53 wild-type cells compared to p53 null cells and HT29. Furthermore, CY induces apoptosis by p53 activation in a dose- and time-dependent manner. And it was confirmed that it affects the L5 gene related to p53. Additionally, CY enhanced p53 expression compared to when either doxorubicin or 5-FU was used alone. Altogether, our findings suggest that CY induces apoptosis via p53 activation and inhibits the proliferation of colon cancer cells. In addition, apoptosis occurs in colon cancer cells due to other factors. Moreover, CY is expected to have a combined effect when used together with existing treatments for colon cancer in the future.

Identification of Key Genes during Ethylene-Induced Adventitious Root Development in Cucumber (Cucumis sativus L.)

Ethylene (ETH), as a key plant hormone, plays critical roles in various processes of plant growth and development. ETH has been reported to induce adventitious rooting. Moreover, our previous studies have shown that exogenous ETH may induce plant adventitious root development in cucumber (Cucumis sativus L.). However, the key genes involved in this process are still unclear. To explore the key genes in ETH-induced adventitious root development, we employed a transcriptome technique and revealed 1415 differentially expressed genes (DEGs), with 687 DEGs up-regulated and 728 DEGs down-regulated. Using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, we further identified critical pathways that were involved in ETH-induced adventitious root development, including carbon metabolism (starch and sucrose metabolism, glycolysis/gluconeogenesis, citrate cycle (TCA cycle), oxidative phosphorylation, fatty acid biosynthesis, and fatty acid degradation), secondary metabolism (phenylalanine metabolism and flavonoid biosynthesis) and plant hormone signal transduction. In carbon metabolism, ETH reduced the content of sucrose, glucose, starch, the activity of sucrose synthase (SS), sucrose–phosphate synthase (SPS) and hexokinase (HK), and the expressions of CsHK2, pyruvate kinase2 (CsPK2), and CsCYP86A1, whereas it enhanced the expressions of β-amylase 1 (CsBAM1) and β-amylase 3 (CsBAM3). In secondary metabolism, the transcript levels of phenylalanine ammonia-lyase (CsPAL) and flavonoid 3′-monooxygenase (CsF3′M) were negatively regulated, and that of primary-amine oxidase (CsPAO) was positively regulated by ETH. Additionally, the indole-3-acetic acid (IAA) content and the expressions of auxin and ETH signaling transduction-related genes (auxin transporter-like protein 5 (CsLAX5), CsGH3.17, CsSUAR50, and CsERS) were suppressed, whereas the abscisic acid (ABA) content and the expressions of ABA and BR signaling transduction-related genes (CsPYL1, CsPYL5, CsPYL8, BRI1-associated kinase 1 (CsBAK1), and CsXTH3) were promoted by ETH. Furthermore, the mRNA levels of these genes were confirmed by real-time PCR (RT-qPCR). These results indicate that genes related to carbon metabolism, secondary metabolite biosynthesis, and plant hormone signaling transduction are involved in ETH-induced adventitious root development. This work identified the key pathways and genes in ETH-induced adventitious rooting in cucumber, which may provide new insights into ETH-induced adventitious root development and will be useful for investigating the molecular roles of key genes in this process in further studies.

Biosynthetic mechanisms of isoflavone accumulation affected by different growth patterns in Astragalus mongholicus products

BACKGROUND

At present, Astragalus mongholicus products on the market represent two growth patterns: imitative wild A. mongholicus (WAM) and cultivated A. mongholicus (CAM). The 6-year-old WAM (A6) and 2-year-old CAM (B2) products are often sold as commodities. This study aimed to explore the effects of the abovementioned growth patterns on the biosynthetic mechanisms of isoflavone accumulation in A. mongholicus products.

RESULTS

In this paper, the content of calycosin-7-O-β-D-glucoside in 6-year-old WAM (A6) was significantly higher than that in 2-year-old CAM (B2) based on high-performance liquid chromatography. Tissue anatomy indicated that A6 has developed phloem fibers, thickened secondary walls, and a more well-developed vascular system than B2. Thirteen differentially accumulated metabolites were found in A6 and B2 by UHPLC-ESI-Q-TOF-MS/MS, of which isoflavones were highly and significantly enriched in A6. By combining transcriptomics and metabolomics analysis, we found that the metabolomics profile was the same as the transcriptomics profile in both A6 and B2. In total, 11 novel isoflavone-related genes were isolated using BLAST and functional annotation through RNA-Seq and Iso-Seq. The results of integrated analysis, Short Time-series Expression Miner analysis, and Pearson correlation analysis showed that the regulation of four key enzymes, cinnamate 4-hydroxylase, 6-deoxychalcone synthase, chalcone reductase, and chalcone isomerase, led to the high accumulation of isoflavones in A6. In addition, AmUFGT (c778119) and AmUCGT (c303354) were predicted to be 7-O-glycosyltransferases by phylogenetic analysis; these genes catalyze formononetin and calycosin, respectively.

CONCLUSIONS

The findings of this work will clarify the differences in the biosynthetic mechanism of isoflavone accumulation between A6 and B2, which will guide the cultivation of A. mongholicus.

Hairy Root Cultures as a Source of Polyphenolic Antioxidants: Flavonoids, Stilbenoids and Hydrolyzable Tannins

Due to their chemical properties and biological activity, antioxidants of plant origin have gained interest as valuable components of the human diet, potential food preservatives and additives, ingredients of cosmetics and factors implicated in tolerance mechanisms against environmental stress. Plant polyphenols are the most prominent and extensively studied, albeit not only group of, secondary plant (specialized) metabolites manifesting antioxidative activity. Because of their potential economic importance, the productive and renewable sources of the compounds are desirable. Over thirty years of research on hairy root cultures, as both producers of secondary plant metabolites and experimental systems to investigate plant biosynthetic pathways, brought about several spectacular achievements. The present review focuses on the Rhizobium rhizogenes-transformed roots that either may be efficient sources of plant-derived antioxidants or were used to elucidate some regulatory mechanisms responsible for the enhanced accumulation of antioxidants in plant tissues.

Heterologous Expression of Three Transcription Factors Differently Regulated Astragalosides Metabolic Biosynthesis in Astragalus membranaceus Hairy Roots

Astragalus membranaceus has been used as a highly popular Chinese herbal medicine for centuries. Triterpenoids, namely astragalosides I, II, III, and IV, represent the main active compounds in this plant species. Transcription factors have a powerful effect on metabolite biosynthesis in plants. We investigated the effect of the Arabidopsis MYB12, production of anthocyanin pigment 1 (PAP1), and maize leaf color (LC) transcription factors in regulating the synthesis of astragaloside metabolites in A. membranaceus. Overexpression of these transcription factors in hairy roots differentially up-regulated these active compounds. Specifically, the overexpression of LC resulted in the accumulation of astragalosides I–IV. The content of astragalosides I and IV were, in particular, more highly accumulated. Overexpression of MYB12 increased the accumulation of astragaloside I in transgenic hairy roots, followed by astragaloside IV, and overexpression of PAP1 resulted in the increased synthesis of astragalosides I and IV. In addition, we found that overexpression of PAP1 together with LC increased astragaloside III levels. At the transcriptional level, several key genes of the mevalonate biosynthetic pathway, especially HMGR1, HMGR2, and HMGR3, were up-regulated differentially in response to these transcription factors, resulting in astragaloside synthesis in the hairy roots of A. membranaceus. Overall, our results indicated that heterologous expression of Arabidopsis MYB12, PAP1, and maize LC differentially affected triterpenoids biosynthesis, leading to the increased biosynthesis of active compounds in A. membranaceus.

Differential Expression of Calycosin-7-O-β-D-glucoside Biosynthesis Genes and Accumulation of Related Metabolites in Different Organs of Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao Under Drought Stress

Calycosin-7-O-β-D-glycoside (CG), as a flavonoid, plays an important role in the abiotic stress response of Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao (A. mongholicus). CG is also an active ingredient in A. mongholicus with high medicinal value. However, the response mechanism of the CG biosynthetic pathway of drought stress is not clear. In this research, drought stress was inflicted upon A. mongholicus, and the variations in flavonoid metabolites and the correlating gene expression in CG biosynthesis were studied in roots, stems, and leaves of A. mongholicus by UHPLC-MRM-MS/MS and qRT-PCR. Drought stress reduced the dry weight and increased the content of malondialdehyde (MDA) and proline. Drought was beneficial to the accumulation of L-phenylalanine and 4-coumaric acid in leaves and promoted the accumulation of all target compounds in the roots, except calycosin. Overexpression of AmIOMT was observed in the leaves, but the content of formononetin which is the product of isoflavone O-methyltransferase (IOMT) catalysis was higher in stems than in leaves. This research aims to further understand the acclimation of abiotic stress and the regulation mechanism of flavonoid accumulation in A. mongholicus.

Expression Analysis of Phenylpropanoid Pathway Genes and Metabolomic Analysis of Phenylpropanoid Compounds in Adventitious, Hairy, and Seedling Roots of Tartary Buckwheat

Tartary buckwheat (Fagopyrum tataricum) is an important crop that belongs to the Polygonaceae family, whose roots have received considerable attention due to the presence of compounds with high nutritional and medicinal value. In this study, we aimed to develop an efficient protocol for the culture of adventitious (ARs) and hairy (HRs) roots on a half-strength Schenk and Hildebrandt (SH) medium containing different concentrations of the auxins, α-naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA), and indole-3-acetic acid (IAA). The highest percentage of root induction (91.67%) was achieved with 0.5 mg/L IAA, whereas the greatest number of roots was found in 1 mg/L IAA. In contrast, 0.1 mg/L IBA returned the longest roots. As expected, HRs were obtained from in vitro leaf explants infected with Agrobacterium rhizogenes R1000. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis of 11 phenolic pathway genes revealed that five genes (FtPAL, FtC3H, FtHQT, FtCHS, and FtANS) were highly expressed in HRs, whereas only four (FtC4H, FtFLS2, FtDFR, and FtANR), and three (Ft4CL, FtCHI, and FtF3H) were recognized in the ARs and seedling roots (SRs), respectively. HPLC analysis of phenolic compounds in different root cultures showed that the majority of the phenolic compounds (both individual and total) were significantly accumulated in the HRs. Principal component analysis (PCA) identified differences among the three root types, whereby HRs were separated from ARs and SRs based on the amount of phenolic compounds present. Analysis of the metabolic pathway revealed that among the identified metabolites, the 3, 2, and 1 pathways were associated with flavonoid, flavone and flavonol, and phenylpropanoid biosynthesis, respectively. Hierarchical clustering analysis and the heat map showed that the different root cultures presented unique metabolites.

Enhancement of Phytosterol and Triterpenoid Production in Plant Hairy Root Cultures-Simultaneous Stimulation or Competition?

Plant in vitro cultures, including hairy roots, can be applied for controlled production of valuable natural products, such as triterpenoids and sterols. These compounds originate from the common precursor squalene. Sterols and triterpenoids distinctly differ in their functions, and the 2,3-oxidosqualene cyclization step is often regarded as a branch point between primary and secondary (more aptly: general and specialized) metabolism. Considering the crucial role of phytosterols as membrane constituents, it has been postulated that unconstrained biosynthesis of triterpenoids can occur when sterol formation is already satisfied, and these compounds are no longer needed for cell growth and division. This hypothesis seems to follow directly the growth-defense trade-off plant dilemma. In this review, we present some examples illustrating the specific interplay between the two divergent pathways for sterol and triterpenoid biosynthesis appearing in root cultures. These studies were significant for revealing the steps of the biosynthetic pathway, understanding the role of particular enzymes, and discovering the possibility of gene regulation. Currently, hairy roots of many plant species can be considered not only as an efficient tool for production of phytochemicals, but also as suitable experimental models for investigations on regulatory mechanisms of plant metabolism.

Full-length transcriptome sequences by a combination of sequencing platforms applied to isoflavonoid and triterpenoid saponin biosynthesis of Astragalus mongholicus Bunge

BACKGROUND

Astragalus mongholicus Bunge is an important medicinal plant used in traditional Chinese medicine. It is rich in isoflavonoids and triterpenoid saponins. Although these active constituents of A. mongholicus have been discovered for a long time, the genetic basis of isoflavonoid and triterpenoid saponin biosynthesis in this plant is virtually unknown because of the lack of a reference genome. Here, we used a combination of next-generation sequencing (NGS) and single-molecule real-time (SMRT) sequencing to identify genes involved in the biosynthetic pathway of secondary metabolites in A. mongholicus.

RESULTS

In this study, NGS, SMRT sequencing, and targeted compound analysis were combined to investigate the association between isoflavonoid and triterpenoid saponin content, and specific gene expression in the root, stem, and leaves of A. mongholicus. Overall, 643,812 CCS reads were generated, yielding 121,107 non-redundant transcript isoforms with an N50 value of 2124 bp. Based on these highly accurate transcripts, 104,756 (86.50%) transcripts were successfully annotated by any of the seven databases (NR, NT, Swissprot, KEGG, KOG, Pfam and GO). Levels of four isoflavonoids and four astragalosides (triterpenoid saponins) were determined. Forty-four differentially expressed genes (DEGs) involved in isoflavonoid biosynthesis and 44 DEGs from 16 gene families that encode enzymes involved in triterpenoid saponin biosynthesis were identified. Transcription factors (TFs) associated with isoflavonoid and triterpenoid saponin biosynthesis, including 72 MYBs, 53 bHLHs, 64 AP2-EREBPs, and 11 bZIPs, were also identified. The above transcripts showed different expression trends in different plant organs.

CONCLUSIONS

This study provides important genetic information on the A. mongholicus genes that are essential for isoflavonoid and triterpenoid saponin biosynthesis, and provides a basis for developing the medicinal value of this plant.

Yeast extract improved biosynthesis of astragalosides in hairy root cultures of Astragalus membranaceus

The dried root of Astragalus membranaceus is a well-known herbal medicine, and it is useful in treating chronic diseases and weakness, as well as for improving overall health and vitality. Astragalosides, which are root quality indicators of A. membranaceus, are natural triterpenoid saponins that are used in the treatment of diabetes and cardiovascular diseases. Currently, there is an urgent need to improve their production because of their low quantity in plants and the difficulty of chemical synthesis. In this study, yeast extract was added to facilitate elicitation in Agrobacterium-mediated hairy root cultures, thereby enhancing astragaloside production in A. membranaceus. Results showed that yeast extract could stimulate astragaloside content effectively in the hairy roots of A. membranaceus. Moreover, astragaloside accumulation was positively correlated with the upregulation of mevalonate biosynthetic gene expression in the presence of yeast extract. Our study demonstrated that pretreatment with yeast extract (3.65 mM) for 72 h serves as an effective strategy to enhance astragaloside levels in A. membranaceus hairy root cultures. Thus, these optimal conditions can provide valuable information for the improvement of astragaloside industrial production in A. membranaceus.

Night Temperature Affects the Growth, Metabolism, and Photosynthetic Gene Expression in Astragalus membranaceus and Codonopsis lanceolata Plug Seedlings

Astragalus membranaceus and Codonopsis lanceolata are two important medical herbs used in traditional Oriental medicine for preventing cancer, obesity, and inflammation. Night temperature is an important factor that influences the plug seedling quality. However, little research has focused on how the night temperature affects the growth and development of plug seedlings of these two medicinal species. In this study, uniform plug seedlings were cultivated in three environmentally controlled chambers for four weeks under three sets of day/night temperatures (25/10 °C, 25/15 °C, or 25/20 °C), the same relative humidity (75%), photoperiod (12 h), and light intensity (150 μmol·m-2·s-1 PPFD) provided by white LEDs. The results showed that night temperature had a marked influence on the growth and development of both species. The night temperature of 15 °C notably enhanced the quality of plug seedlings evidenced by the increased shoot, root, and leaf dry weights, stem diameter, and Dickson's quality index. Moreover, a night temperature of 15 °C also stimulated and increased contents of primary and secondary metabolites, including soluble sugar, starch, total phenols and flavonoids. Furthermore, the 15 °C night temperature increased the chlorophyll content and stomatal conductance and decreased the hydrogen peroxide content. Analysis of the gene expression showed that granule-bound starch synthase (GBSS), ribulose bisphosphate carboxylase large chain (RBCL), and ferredoxin (FDX) were up-regulated when the night temperature was 15 °C. Taken together, the results suggested that 15 °C is the optimal night temperature for the growth and development of plug seedlings of A. membranaceus and C. lanceolata.

Identification and quantification of phenolic compounds of Western Siberia Astragalus danicus in different regions

The potential of phenolic compounds of medicinal plants including Astragalus danicus L is determined by but not limited to their antioxidant activity. Their anti-inflammatory, antitumor, and other useful properties are known, which allows using these phytochemicals within preventive activities to reduce the risk of many serious diseases. Chromatographic analysis of the Astragalus danicus L. biomaterial from the plant samples collected in three regions of the Kemerovo region (Western Siberia, Russia) established the presence of compounds of flavonols (isorhamnetin glucoside, kaempferol glucoside), flavones (apigenin 7-glucoside), phenylpropanoids (chlorogenic acid) in the aerial part of plants. The total content of phenolic compounds in plant samples ranged from 100.75 ± 3.87 mg/g (Yashkinsky district) to 190.95 ± 7.34 mg/g (Belovsky district). The content of chlorogenic acid in the studied samples was from 0.14 ± 0.01 mg/g to 1.16 ± 0.04 mg/g. Isorhamnetin glucoside was found only in samples of plants from two districts - Prokopievsky (41.39 ± 1.58 mg/g) and Belovsky (95.0 ± 3.66 mg/g). The content of glucosides of kaempferol ranged from 0.38 ± 0.01 mg/g to 0.55 ± 0.02 mg/g. Its content is almost twice as high as the content in the well-known analogues of Astragalus. Apigenin-7-glucoside was isolated in Astragalus samples for the first time, in a small amount (3.34 ± 0.13 mg/g) in a sample of plants of one growing zone. Studies have confirmed that the content of flavonoids in plants significantly depends not only on the genetic characteristics of plants, but also on the hydrothermal regime, the climatic conditions of different botanical and geographical areas of the habitat. This work shows that Astragalus danicus L. growing in Kemerovo region is a promising raw material for pharmacological preparations.

Protective Effects of Combination of Radix Astragali and Radix Salviae Miltiorrhizae on Kidney of Spontaneously Hypertensive Rats and Renal Intrinsic Cells

OBJECTIVE

To evaluate the effects of combination of Radix Astragali (RA) and Radix Salviae Miltiorrhizae (RS) on kidney of spontaneously hypertensive rats (SHRs) and renal intrinsic cells.

METHODS

SHRs were intragastrically administrated with RA (5.09 g/kg) and RS (2.55 g/kg) either alone or with combination for 4 weeks; valsartan (13.35 mg/kg) was used as a positive control. Blood pressure and renal ultrasonography were monitored periodically. The biomarkers [microalbumin (mALB), cystatin ^C, angiotensin II (Ang II), interleukin-1 beta (IL-1β), and β2-microglobulin (β2-Mg), etc.] in serum and urine were measured by enzyme-linked immunosorbent assay (ELISA). The protein expressions [phosphorylated adenosine 5'-monophosphate-activated protein kinase-α1 (p-AMPKα1), sestrin-β, calcium/calmodulin-dependent protein kinase kinase-β (CaMKK-β), phosphoinositide 3-kinases (PI3K), serine-threonine protein kinase 1 (AKT1), and vascular endothelial growth factor receptor 2 (VEGFR2)] in renal cortex were determined by Western blot. In vitro, the hypertensive cellular model was established by applying 2×10^-6 mol/L Ang ^II. The primary human podocytes, human glomerular endothelial cells (HRGECs), and human proximal tubular epithelial cells (HK-2s) were pre-incubated with sulfotanshinone sodium (Tan, 10 μg/mL) and/or calycosin-7-O-β-D-glucoside (Cal, 5 μg/mL). The cellular viability and apoptosis were assayed by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and Annexin V/PI staining, respectively. The level of endothelial nitric oxide synthase (eNOS) in culture supernatant was determined by ELISA.

RESULTS

RA+RS signifificantly decreased the diastolic blood pressure, renal vascular resistance index, and parenchymal thickness, increased 24 h urinary volume as well as lowered the levels of urine mALB and serum cystatin ^C, IL-1β and β2-Mg of SHRs (P <0.05 vs. SHRs). The decreased protein levels of p-AMPKα1, sestrinβ and CaMKK-β and the increased protein levels of PI3K, AKT1 and VEGFR2 in renal cortex of SHRs were normalized after RA+RS treatment (P <0.05). In vitro, Tan and Cal attenuated the Ang II-induced abnormal proliferation and increased the apoptosis of HRGECs and HK-2s and improved the level of eNOS in culture supernatant. Whereas, neither of them showed powerful effect on podocyte.

CONCLUSION

The combination of RA and RS had potential effects on alleviating the renal damages of SHRs and the renoprotection was independent of blood pressure level.

Potential Anticancer Properties and Mechanisms of Action of Formononetin

Nature, a vast reservoir of pharmacologically active molecules, has been most promising source of drug leads for the cure of various pathological conditions. Formononetin is one of the bioactive isoflavones isolated from different plants mainly from Trifolium pratense, Glycine max, Sophora flavescens, Pycnanthus angolensis, and Astragalus membranaceus. Formononetin has been well-documented for its anti-inflammatory, anticancer, and antioxidant properties. Recently anticancer activity of formononetin is widely studied. This review aims to highlight the pharmacological potential of formononetin, thus providing an insight of its status in cancer therapeutics. Formononetin fights progression of cancer via inducing apoptosis, arresting cell cycle, and halting metastasis via targeting various pathways which are generally modulated in several cancers. Although reported data acclaims various biological properties of formononetin, further experimentation on mechanism of its action, medicinal chemistry studies, and preclinical investigations are surely needed to figure out full array of its pharmacological and biological potential.

Comparative metabolomics of scab-resistant and susceptible apple cell cultures in response to scab fungus elicitor treatment

Apple scab disease caused by the fungus Venturia inaequalis is a devastating disease that seriously affects quality and yield of apples. In order to understand the mechanisms involved in scab resistance, we performed gas chromatography-mass spectrometry based metabolomics analysis of the cell culture of scab resistant cultivar 'Florina' and scab susceptible cultivar 'Vista Bella' both prior -to and -following treatment with V. inaequalis elicitor (VIE). A total 21 metabolites were identified to be altered significantly in 'Florina' cell cultures upon VIE-treatment. Among 21 metabolites, formation of three new specialized metabolites aucuparin, noraucuparin and eriobofuran were observed only in resistant cultivar 'Florina' after the elicitor treatment. The score plots of principal component analysis (PCA) exhibited clear discrimination between untreated and VIE-treated samples. The alteration in metabolite levels correlated well with the changes in the transcript levels of selected secondary metabolite biosynthesis genes. Aucuparin, noraucuparin and eriobofuran isolated from the 'Florina' cultures showed significant inhibitory effect on the conidial germination of V. inaequalis. The results expand our understanding of the metabolic basis of scab-resistance in apple and therefore are of interest in apple breeding programs to fortify scab resistance potential of commercially grown apple cultivars.

Evaluation of the Pharmaceutical Properties and Value of Astragali Radix

Astragali Radix (AR), a Chinese materia medica (CMM) known as Huangqi, is an important medicine prescribed in herbal composite formulae (Fufang) by Traditional Chinese medicine (TCM) practitioners for thousands of years. According to the literature, AR is suggested for patients suffering from “Qi”- and “Blood”-deficiencies, and its clinical effects are reported to be related to anti-cancer cell proliferation, anti-oxidation, relief of complications in cardiovascular diseases, etc. The underlying cell signaling pathways involved in the regulation of these various diseases are presented here to support the mechanisms of action of AR. There are two botanical sources recorded in China Pharmacopoeia (CP, 2015): Astragalus membranaceus (Fisch.) Bge. Var. mongohlicus, (Bge.) Hsiao, and Astragalus membranaceus (Fisch.) Bge. (Fam. Leguminosae), whose extracts of dried roots are processed via homogenization-assisted negative pressure cavitation extraction. Geographic factors and extraction methods have impacts on the pharmaceutical and chemical profiles of AR. Therefore, the levels of the major bioactive constituents of AR, including polysaccharides, saponins, and flavonoids, may not be consistent in different batches of extract, and the pharmaceutical efficacy of these bioactive ingredients may vary depending on the source. Therefore, the present review mainly focuses on the consistency of the available sources of AR and extracts and on the investigation of the biological functions and mechanisms of action of AR and of its major bioactive constituents. Furthermore, it will also include a discussion of the most popular AR composite formulae to further elucidate their chemical and biological profiles and understand the pharmaceutical value of AR.

A rapid method for sensitive profiling of bioactive triterpene and flavonoid from Astragalus mongholicus and Astragalus membranaceus by ultra-pressure liquid chromatography with tandem mass spectrometry

Astragalus is one of the most popular Chinese herbal. Control of Astragalus quantity is most important, since that various varieties and ages largely affect bioactive metabolites and different pharmacological effects. Astragalus mongholicus and Astragalus membranaceus are both major sources of Astragalus according to the provisions in the Chinese Pharmacopoeia. Thus, a sensitive and rapid UPLC-MS/MS method for the simultaneous determination of l-Phenylalanine, Isoliquiritigenin, Liquiritigenin, Daidzein, Formononetin, Ononin, Calycosin, Calycosin-7-glucoside, Cycloastragenol, Astragaloside I, Astragaloside II, Astragaloside III and Astragaloside IV was established in this study. The detection was accomplished by MRM scanning in the positive ionization mode. Calibration curves offered linear ranges with r² > 0.999. The method was successfully validated for the linearity, intra-day and inter day precisions, accuracy, recovery, matrix effect and stability. Then this method was successfully applied to detect the contents of 13 target flavonoids and triterpenoids metabolites in different organs and ages of A. mongholicus and A. membranaceus. Significant organs-, ages- and varieties- specificity of the 13 target metabolites were observed and discussed. The results provided basis and support for further exploration of the distribution of bioactive metabolites, namely flavonoids and triterpenoids, in different organs and ages of two Astragalus varieties. This method should be applicable to various Astragalus matrices for the quantitative analysis of the target flavonoids and triterpenoids.

Identification and Characterization of Phenylpropanoid Biosynthetic Genes and Their Accumulation in Bitter Melon (Momordica charantia)

Phenylpropanoids and flavonoids belong to a large group of secondary metabolites, and are considered to have antioxidant activity, which protects the cells against biotic and abiotic stresses. However, the accumulation of phenylpropanoids and flavonoids in bitter melon has rarely been studied. Here, we identify ten putative phenylpropanoid and flavonoid biosynthetic genes in bitter melon. Most genes were highly expressed in leaves and/or flowers. HPLC analysis showed that rutin and epicatechin were the most abundant compounds in bitter melon. Rutin content was the highest in leaves, whereas epicatechin was highly accumulated in flowers and fruits. The accumulation patterns of trans-cinnamic acid, p-coumaric acid, ferulic acid, kaempferol, and rutin coincide with the expression patterns of McPAL, McC4H, McCOMT, McFLS, and Mc3GT, respectively, suggesting that these genes play important roles in phenylpropanoid and flavonoid biosynthesis in bitter melon. In addition, we also investigated the optimum light conditions for enhancing phenylpropanoid and flavonoid biosynthesis and found that blue light was the most effective wavelength for enhanced accumulation of phenylpropanoids and flavonoids in bitter melon.

Rapid Analysis and Guided Isolation of Astragalus Isoflavonoids by UHPLC-DAD-MSn and Their Cellular Antioxidant Defense on High-Glucose-Induced Mesangial Cell Dysfunction

Isoflavonoids, including isoflavones, isoflavans, and pterocarpans, the principal components in Astragalus membranaceus, have a great deal of versatile health-promoting benefits. In this work, as a continuation of our search for bioactive constituents from A. membranaceus, a fast high-performance liquid chromatography-diode array detection-multiple-stage mass spectrometry method was first used to analyze the isoflavonoid profile of A. membranaceus roots extract. Twelve diverse isoflavonoids in subclasses of isoflavones, isoflavans, and pterocarpans present in glycoside/aglycone pair forms were tentatively characterized; of those 12, eight major isoflavonoids were finally isolated and simultaneously quantified by the established fast UHPLC method. Furthermore, the results confirmed for the first time that Astragalus isoflavonoid aglycones could attenuate mesangial cell proliferation and extracellular matrix (ECM) accumulation triggered by high glucose levels, and the primary mechanism might be via protecting intracellular antioxidant enzymes activities and enhancing endogenous antioxidant function to lower levels of cellular oxidative damage induced by high glucose levels. Collectively, diverse Astragalus isoflavonoid antioxidants have the potential to ameliorate high-glucose-induced mesangial cell dysfunction through the regulation of cellular antioxidant defense.

Simultaneous determination of six active metabolites in Astragalus mongholicus (Fisch.) Bge. under salt stress by ultra-pressure liquid chromatography with tandem mass spectrometry

Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao (A. mongholicus, family Leguminosae) is one of the most important traditional Chinese herbs because it contains lots of bioactive metabolites, which have beneficial and pharmacological effects on health. Simultaneously, it has been proved to be a salt-tolerant plant-one of the potential species to control the soil salinization. Therefore, a sensitive and specific ultra-pressure liquid chromatography coupled with tandem mass spectrometric (UPLC-MS/MS) method was developed and validated for the simultaneous determination of six main bioactive metabolites, astragaloside IV, cycloastragenol, calycosin-7-O-β-d-glucoside, calycosin, ononin and formononetin in different organs of A. mongholicus. The detection was accomplished by multiple-reaction monitoring (MRM) scanning via electrospray ionization source operating in the positive ionization mode. Calibration curves offered linear ranges of two orders of magnitude with R(2) > 0.99. The method was fully validated for the linearity, intra-day and inter day precisions, accuracy, recovery, matrix effect and stability. Then this method was successfully applied to detect the content of major bioactive metabolites in different plant organs of A. mongholicus under salt stress. Significant variations in the content of six bioactive metabolites were observed after been processed by different levels of salinity in different part of plant. The results support for further exploration of the salt-tolerant mechanisms in A. mongholicus and its possibility as the species that control the soil salinization. Meanwhile, we established a UPLC-MS/MS assay of the trace components in seedling of A. mongholicus in this study.

Allelochemicals from the Rhizosphere Soil of Cultivated Astragalus hoantchy

Astragalus hoantchy, a widely cultivated medicinal plant species in traditional Chinese and Mongolian medicine, has been often hampered by replant failure during cultivation, like many other herbs of the genus Astragalus. Root aqueous extracts of Astragalus herbs were reported to exhibit allelopathic activity against other plants and autotoxic activity on their own seedlings, but the allelochemicals released by Astragalus plants have not been specified so far. Ten compounds were isolated from the rhizosphere soil extract of cultivated A. hoantchy and elucidated by spectroscopic analysis. Compounds 1-6 observably showed allelopathic activity against Lactuca sativa seedlings and autotoxic activity against A. hoantchy seedlings. The isolated compounds were further confirmed and quantified by high-performance liquid chromatography (HPLC) in the rhizosphere soil, with a total concentration of 9.78 μg/g (dry weight). These results specify and verify the allelochemicals released by cultivated A. hoantchy into the soil environment, which may provide new insights into the allelopathic mechanisms of this medicinal plant and probably assist in clarifying the replant problems of Astragalus plants.