Synergistic induction of phytoalexins in Nicotiana attenuata by jasmonate and ethylene signaling mediated by NaWRKY70.

Production of the phytoalexins scopoletin and scopolin is regulated by jasmonate (JA) and ethylene signaling in Nicotiana species in response to Alternaria alternata, the necrotrophic fungal pathogen that causes brown spot disease. However, how these two signaling pathways are coordinated to control this process remains unclear. In this study, we found that the levels of these two phytoalexins and transcripts of their key enzyme gene, feruloyl-CoA 6'-hydroxylase 1 (NaF6'H1), were synergistically induced in Nicotiana attenuata by co-treatment with methyl jasmonate (MeJA) and ethephon. By combination of RNA sequencing and virus-induced gene silencing, we identified a WRKY transcription factor, NaWRKY70, which had a similar expression pattern to NaF6'H1 and was responsible for A. alternata-induced NaF6'H1 expression. Further evidence from stable transformed plants with RNA interference, knock out and overexpression of NaWRKY70 demonstrated that it is a key player in the synergistic induction of phytoalexins and plant resistance to A. alternata. Electrophoretic mobility shift, chromatin immunoprecipitation-quantitative PCR, and dual-luciferase assays revealed that NaWRKY70 can bind directly to the NaF6'H1 promoter and activate its expression. Furthermore, the key regulator of the ethylene pathway, NaEIN3-like1, can directly bind to the NaWRKY70 promoter and activate its expression. Meanwhile, NaMYC2s, important JA pathway transcription factors, also indirectly regulate the expression of NaWRKY70 and NaF6'H1 to control scopoletin and scopolin production. Our data reveal that these phytoalexins are synergistically induced by JA and ethylene signaling during A. alternata infection, which is largely mediated by NaWRKY70, thus providing new insights into the defense responses against A. alternata in Nicotiana species.

Multi-omics reveal key enzymes involved in the formation of phenylpropanoid glucosides in Artemisia annua.

Although mainly known for producing artemisinin, Artemisia annua is enriched in phenylpropanoid glucosides (PGs) with significant bioactivities. However, the biosynthesis of A. annua PGs is insufficiently investigated. Different A. annua ecotypes from distinct growing environments accumulate varying amounts of metabolites, including artemisinin and PGs such as scopolin. UDP-glucose:phenylpropanoid glucosyltransferases (UGTs) transfers glucose from UDP-glucose in PG biosynthesis. Here, we found that the low-artemisinin ecotype GS produces a higher amount of scopolin, compared to the high-artemisinin ecotype HN. By combining transcriptome and proteome analyses, we selected 28 candidate AaUGTs from 177 annotated AaUGTs. Using AlphaFold structural prediction and molecular docking, we determined the binding affinities of 16 AaUGTs. Seven of the AaUGTs enzymatically glycosylated phenylpropanoids. AaUGT25 converted scopoletin to scopolin and esculetin to esculin. The lack of accumulation of esculin in the leaf and the high catalytic efficiency of AaUGT25 on esculetin suggest that esculetin is methylated to scopoletin, the precursor of scopolin. We also discovered that AaOMT1, a previously uncharacterized O-methyltransferase, converts esculetin to scopoletin, suggesting an alternative route for producing scopoletin, which contributes to the high-level accumulation of scopolin in A. annua leaves. AaUGT1 and AaUGT25 responded to induction of stress-related phytohormones, implying the involvement of PGs in stress responses.

Anti-Alopecia Activity of Coumarin Derivatives Isolated from Merremia peltata Leaves and Computational Study of Their Binding to Androgen Receptors Using Molecular Docking and Molecular Dynamic Simulation.

Alopecia is a condition in which hair on the scalp or other areas of the body is lost or falls out excessively. Nutritional deficiency causes blood flow to the head to decrease causing the hormone testosterone to be changed by the enzyme 5-α-reductase to dihydrotestosterone, which inhibits the growth phase and accelerates the death phase. One of the methods developed to treat alopecia is through inhibition of the 5-α-reductase enzyme, which converts testosterone to its more potent metabolite, dihydrotestosterone (DHT). Ethnomedicinally, Merremia peltata leaf is used by the people of Sulawesi as a remedy for baldness. Therefore, in this research, an in vivo study was conducted on rabbits to determine the anti-alopecia activity of M. peltata leaf compounds. The structure of the compounds isolated from the M. peltata leaf ethyl acetate fraction was determined by analysis of NMR and LC-MS data. An in silico study was then carried out using minoxidil as a comparison ligand; scopolin (1) and scopoletin (2) isolated from M. peltata leaf were identified as anti-alopecia compounds by predicting docking, simulating molecular dynamics and predicting absorption, distribution, metabolism, excretion, and toxicology (ADME-Tox). Compounds 1 and 2 had a better effect on hair growth compared to positive controls, and NMR and LC-MS analysis showed that they had comparable binding energies to receptors in the molecular docking interaction study: -4.51 and -4.65 kcal/mol, respectively, compared to -4.8 kcal/mol for minoxidil. Molecular dynamics simulation analysis with the parameters binding free energy calculated using the MM-PBSA method and complex stability based on SASA, PCA, RMSD, and RMSF showed that scopolin (1) has a good affinity for androgens receptors. The ADME-Tox prediction for scopolin (1) showed good results for the parameters of skin permeability, absorption and distribution. Therefore, scopolin (1) is a potential antagonist to androgen receptors and could be useful in the treatment of alopecia.

The Use of Spectral Imaging to Follow the Iron and pH-Dependent Accumulation of Fluorescent Coumarins.

Plants challenged with iron deficiency produce in their roots and secrete into the rhizosphere several small molecules named coumarins that derive from the phenylpropanoid pathway. Coumarins are biosynthesized in different root cell types and transported to the root epidermis prior to their secretion in the surrounding media. Taking advantage of the natural fluorescence of most coumarins glycosides when exposed to UV light, we developed a method to uncover their individual cellular localization and accumulation. This approach couples spectral imaging acquisition and linear unmixing analysis. In this protocol, we describe guidelines, experimental setup, and conditions for the analysis of coumarins localization and accumulation in Arabidopsis thaliana root seedlings grown in control and iron deficiency conditions, at both acidic and alkaline pH.

[Expression of ß-glucosidase An-bgl3 from Aspergillus niger for conversion of scopolin].

Scopoletin is a coumarin compound with various biological activities including detumescence and analgesic, insecticidal, antibacterial and acaricidal effects. However, interference with scopolin and other components often leads to difficulties in purification of scopoletin with low extraction rates from plant resource. In this paper, heterologous expression of the gene encoding ß-glucosidase An-bgl3 derived from Aspergillus niger were carried out. The expression product was purified and characterized with further structure-activity relationship between it and ß-glucosidase analyzed. Subsequently, its ability for transforming scopolin from plant extract was studied. The results showed that the specific activity of the purified ß-glucosidase An-bgl3 was 15.22 IU/mg, the apparent molecular weight was about 120 kDa. The optimum reaction temperature and pH were 55 ℃ and 4.0, respectively. Moreover, 10 mmol/L metal ions Fe2+ and Mn2+ increased the enzyme activity by 1.74-fold and 1.20-fold, respectively. A 10 mmol/L solution containing Tween-20, Tween-80 and Triton X-100 all inhibited the enzyme activity by 30%. The enzyme showed affinity towards scopolin and tolerated 10% methanol and 10% ethanol solution, respectively. The enzyme specifically hydrolyzed scopolin into scopoletin from the extract of Erycibe obtusifolia Benth with a 47.8% increase of scopoletin. This demonstrated that the ß-glucosidase An-bgl3 from A. niger shows specificity on scopolin with good activities, thus providing an alternative method for increasing the extraction efficiency of scopoletin from plant material.

Expression of β-glucosidase An-bgl3 from Aspergillus niger for conversion of scopolin / 生物工程学报

Scopoletin is a coumarin compound with various biological activities including detumescence and analgesic, insecticidal, antibacterial and acaricidal effects. However, interference with scopolin and other components often leads to difficulties in purification of scopoletin with low extraction rates from plant resource. In this paper, heterologous expression of the gene encoding β-glucosidase An-bgl3 derived from Aspergillus niger were carried out. The expression product was purified and characterized with further structure-activity relationship between it and β-glucosidase analyzed. Subsequently, its ability for transforming scopolin from plant extract was studied. The results showed that the specific activity of the purified β-glucosidase An-bgl3 was 15.22 IU/mg, the apparent molecular weight was about 120 kDa. The optimum reaction temperature and pH were 55 ℃ and 4.0, respectively. Moreover, 10 mmol/L metal ions Fe2+ and Mn2+ increased the enzyme activity by 1.74-fold and 1.20-fold, respectively. A 10 mmol/L solution containing Tween-20, Tween-80 and Triton X-100 all inhibited the enzyme activity by 30%. The enzyme showed affinity towards scopolin and tolerated 10% methanol and 10% ethanol solution, respectively. The enzyme specifically hydrolyzed scopolin into scopoletin from the extract of Erycibe obtusifolia Benth with a 47.8% increase of scopoletin. This demonstrated that the β-glucosidase An-bgl3 from A. niger shows specificity on scopolin with good activities, thus providing an alternative method for increasing the extraction efficiency of scopoletin from plant material.

Knockdown of p-Coumaroyl Shikimate/Quinate 3'-Hydroxylase Delays the Occurrence of Post-Harvest Physiological Deterioration in Cassava Storage Roots.

Cassava storage roots are an important source of food, feed, and material for starch-based industries in many countries. After harvest, rapid post-harvest physiological deterioration (PPD) reduces their palatability and marketability. During the PPD process, vascular streaking occurs through over-accumulation of coumarins, the biosynthesis of which involves the key enzyme p-coumaroyl shikimate/quinate 3'-hydroxylase (C3'H). Repression of MeC3'H expression by RNA interference in transgenic cassava plants caused a significant delay in PPD by decreasing scopoletin and scopolin accumulation in field-harvested storage roots. This study demonstrates that MeC3'H is the key enzyme participating in coumarin biosynthesis during PPD and shows that MeC3'H is a useful target gene for editing to prolong the shelf life of cassava storage roots.

Retrieving the in vivo Scopoletin Fluorescence Excitation Band Allows the Non-invasive Investigation of the Plant-Pathogen Early Events in Tobacco Leaves.

In this study, we developed and applied a new spectroscopic fluorescence method for the in vivo detection of the early events in the interaction between tobacco (Nicotiana tabacum L.) plants and pathogenic bacteria. The leaf disks were infiltrated with a bacterial suspension in sterile physiological solution (SPS), or with SPS alone as control. The virulent Pseudomonas syringae pv. tabaci strain ATCC 11528, its non-pathogenic ΔhrpA mutant, and the avirulent P. syringae pv. tomato strain DC3000 were used. At different post-infiltration time-points, the in vivo fluorescence spectra on leaf disks were acquired by a fiber bundle-spectrofluorimeter. The excitation spectra of the leaf blue emission at 460 nm, which is mainly due to the accumulation of coumarins following a bacterial infiltration, were processed by using a two-bands Gaussian fitting that enabled us to isolate the scopoletin (SCT) contribution. The pH-dependent fluorescence of SCT and scopolin (SCL), as determined by in vitro data and their intracellular localization, as determined by confocal microscopy, suggested the use of the longer wavelength excitation band at 385 nm of 460 nm emission (F385_460) to follow the metabolic evolution of SCT during the plant-bacteria interaction. It was found to be directly correlated (R 2 = 0.84) to the leaf SCT content, but not to that of SCL, determined by HPLC analysis. The technique applied to the time-course monitoring of the bacteria-plant interaction clearly showed that the amount and the timing of SCT accumulation, estimated by F385_460, was correlated with the resistance to the pathogen. As expected, this host defense response was delayed after P. syringae pv. tabaci ATCC 11528 infiltration, in comparison to P. syringae pv. tomato DC3000. Furthermore, no significant increase of F385_460 (SCT) was observed when using the non-pathogenic ΔhrpA mutant of P. syringae pv. tabaci ATCC 11528, which lacks a functional Type Three Secretion System (TTSS). Our study showed the reliability of the developed fluorimetric method for a rapid and non-invasive monitoring of bacteria-induced first events related to the metabolite-based defense response in tobacco leaves. This technique could allow a fast selection of pathogen-resistant cultivars, as well as the on-site early diagnosis of tobacco plant diseases by using suitable fluorescence sensors.

Coumarin accumulation and trafficking in Arabidopsis thaliana: a complex and dynamic process.

Iron (Fe) is a major micronutrient and is required for plant growth and development. Nongrass species have evolved a reduction-based strategy to solubilize and take up Fe. The secretion of Fe-mobilizing coumarins (e.g. fraxetin, esculetin and sideretin) by plant roots plays an important role in this process. Although the biochemical mechanisms leading to their biosynthesis have been well described, very little is known about their cellular and subcellular localization or their mobility within plant tissues. Spectral imaging was used to monitor, in Arabidopsis thaliana, the in planta localization of Fe-mobilizing coumarins and scopolin. Molecular, genetic and biochemical approaches were also used to investigate the dynamics of coumarin accumulation in roots. These approaches showed that root hairs play a major role in scopoletin secretion, whereas fraxetin and esculetin secretion occurs through all epidermis cells. The findings of this study also showed that the transport of coumarins from the cortex to the rhizosphere relies on the PDR9 transporter under Fe-deficient conditions. Additional experiments support the idea that coumarins move throughout the plant body via the xylem sap and that several plant species can take up coumarins present in the surrounding media. Altogether, the data presented here demonstrate that coumarin storage and accumulation in roots is a highly complex and dynamic process.

Scopolin Prevents Adipocyte Differentiation in 3T3-L1 Preadipocytes and Weight Gain in an Ovariectomy-Induced Obese Mouse Model.

Obesity is prevalent in modern human societies. We examined the anti-obesity effects of scopolin on adipocyte differentiation in preadipocyte 3T3-L1 cells and weight loss in an ovariectomy (OVX)-induced obese mouse model. Scopolin inhibited adipocyte differentiation and lipid accumulation in the preadipocyte cells by suppressing the transcription of adipogenic-related factors, including adiponectin (Adipoq), peroxisome proliferator-activated receptor gamma (Pparg), lipoprotein lipase (Lpl), perilipin1 (Plin1), fatty acid-binding protein 4 (Fabp4), glucose transporter type 4 (Slc2a4), and CCAAT/enhancer-binding protein alpha (Cebpa). In OVX-induced obese mice, administration of scopolin promoted the reduction of body weight, total fat percentage, liver steatosis, and adipose cell size. In addition, the scopolin-treated OVX mice showed decreased serum levels of leptin and insulin. Taken together, these findings suggest that the use of scopolin prevented adipocyte differentiation and weight gain in vitro and in vivo, indicating that scopolin may be a potential bioactive compound for the treatment and prevention of obesity in humans.

Scopolin Attenuates Osteoporotic Bone Loss in Ovariectomized Mice.

Bone remodeling is a renewal process regulated by bone synthesis (osteoblasts) and bone destruction (osteoclasts). A previous study demonstrated that Lycii radicis cortex (LRC) extract inhibited ovariectomized (OVX)-induced bone loss in mice. This study investigated the anti-osteoporotic effects of bioactive constituent(s) from the LRC extract. The effective compound(s) were screened, and a single compound, scopolin, which acts as a phytoalexin, was chosen as a candidate component. Scopolin treatment enhanced alkaline phosphatase activity and increased mineralized nodule formation in MC3T3-E1 pre-osteoblastic cells. However, osteoclast differentiation in primary-cultured monocytes was reduced by treatment with scopolin. Consistently, scopolin treatment increased osteoblast differentiation in the co-culture of monocytes (osteoclasts) and MC3T3-E1 (osteoblast) cells. Scopolin treatment prevented bone mineral density loss in OVX-induced osteoporotic mice. These results suggest that scopolin could be a therapeutic bioactive constituent for the treatment and prevention of osteoporosis.

[The "chemical defense" of plants against pathogenic microbes: Phytoalexins biosynthesis and molecular regulations]. / æ¤ç‰©å¯¹ç— åŽŸå¾®ç”Ÿç‰©çš„"化学防御": æ¤ä¿ç´ çš„ç”Ÿç‰©åˆæˆåŠå ¶åˆ†å­è°ƒæŽ§æœºåˆ¶.

Plants can produce diverse groups of secondary metabolites to adapt to environment. Many secondary metabolites are involved in the defense responses against pathogenic microbes, including phytoanticipins which are low molecular weight anti-microbial compounds presented in plants before infection, and phytoalexins produced by plants de novo in response to pathogen attack. Phytoalexins are an important part of plant defense repertoire to pathogenic microbes, especially to necrotrophs. Since the concept of phytoalexin was proposed 80 years ago, many kinds of phytoalexins were identified. In contrast, the biosynthesis of most phytoalexins and their regulatory networks are largely unknown. In this review, I summarized recent research progress of phytoalexins in Arabidopsis and Nicotiana species, with special focus on molecular regulations of their biosynthesis. The problems and future directions in phytoalexin research were also discussed.

Phytochemical analysis and geographic assessment of flavonoids, coumarins and sesquiterpenes in Artemisia annua L. based on HPLC-DAD quantification and LC-ESI-QTOF-MS/MS confirmation.

To evaluate the quality of Artemisia annua L., an accurate HPLC-DAD method has been developed, validated and applied to the simultaneous quantification of five flavonoids, two coumarins and four sesquiterpenes. An LC-ESI-QTOF-MS/MS confirmation method has been utilized to avoid false-positive results. Principal component analysis and hierarchical cluster analysis results indicated that their contents had obvious regional characteristics. Samples with high contents of artemisinin (8.24 ± 2.92 mg/g) and isorhamnetin (0.28 ± 0.25 mg/g) are mainly distributed south of the Yangtze River, and samples with high contents of scopolin (0.46 ± 0.22 mg/g), scopoletin (1.05 ± 0.17 mg/g), chrysosplenol D (0.64 ± 0.14 mg/g), casticin (1.07 ± 0.23 mg/g), arteannuin B (0.69 ± 0.18 mg/g) and artemisinic acid (3.02 ± 1.00 mg/g) are mainly distributed in eastern and northern China. Geographic content differences of the components in A. annua indicate the potential differences in the health-promoting effects of its clinical application.

Studies on chemical constituents of Chloranthus fortunei / 中草药

Objective: To study the antitumor constituents from Chloranthus fortunei. Methods: Various chromatographic techniques and spectroscopic methods were applied to investigate the chemical constituents from C. fortunei, and some of the compounds were screened for their antitumor activities by MTT method. Results: Sixteen compounds were obtained from the whole plants of C. fortunei and identified as rosmarinic acid (1), 2’-hydroxy-4,3’,4’,6’-tetramethoxychalcone (2), flavokawain A (3), cycloshizukaol A (4), atractylenolide III (5), 4β-hydroxy-8,12-epoxyeudesma-7,11-diene-1,6-dione (6), (8α)-6,8-dihydroxycadina-7 (11),10 (15)-dien-12-oic acid γ-lactone (7), curcolonol (8), 11-hydroxyldrim-8,12-en-14-oic acid (9), friedelin (10), isovanillic acid (11), 6β-hydroxystigmast-4-en-3-one (12), 3,4-dihydroxybenzoic acid (13), shikimic acid (14), scopolin (15) and N-acetyltyramine 1-O-β-D-glucoside (16). Compounds 4 and 5 showed weak cytotoxicity with IC50 ranged from 46 to 85 μmol/L. Conclusion: Compounds 2, 10, 11, and 13-15 are obtained from the genus Chloranthus for the first time and compounds 1-3 and 6-16 are isolated from C. fortunei for the first time. Some sesquiterpenoids from C. fortunei exhibited weak antitumor activities.

Evaluation of pharmacokinetics, bioavailability and urinary excretion of scopolin and its metabolite scopoletin in Sprague Dawley rats by liquid chromatography-tandem mass spectrometry.

We aimed to investigate the pharmacokinetics, bioavailability and urinary excretion of scopolin and its metabolite scopoletin in rats. An LC-tandem mass spectrometry (MS/MS) method for simultaneous determination of scopolin and scopoletin in rat biomatrices was developed and validated over a plasma and urine concentration range of 5.0-2000 ng/mL. Chromatographic separation was performed on a Hypersil GOLD C18 column with acetonitrile and 0.1% formic acid in water as mobile phase with gradient elution. Detection was performed in the positive ionization and selected reaction monitoring mode. The intra- and inter-batch precision and accuracy, extraction recovery and matrix effect and stability of scopolin and scopoletin were well within the acceptable limits of variation. There was no gender-related difference in the pharmacokinetic profiles of scopolin. There were significant differences in total area under the concentration-time curve (AUC), time required to achieve a maximal concentration (Tmax ) and apparent clearance from plasma (Cl/F) of scopoletin between the male and female rats (p < .05). The bioavailability (F) of scopolin was exceptionally low. The maximal excretion rates were 7.61 µg/h and 7.15 µg/h for scopolin and 31.68 µg/h and 25.58 µg/h for scopoletin in male and female rats, respectively. The LC-MS/MS method was successfully applied to the pharmacokinetic, bioavailability and urinary excretion studies of scopolin and its metabolite scopoletin following a single administration of scopolin to rats.

Time-resolved fluorescence and chemometrics-assisted excitation-emission fluorescence for qualitative and quantitative analysis of scopoletin and scopolin in Erycibe obtusifolia Benth.

This paper presents a new strategy for qualitative identification of scopoletin and scopolin in Erycibe obtusifolia Benth using time-resolved (lifetimes) fluorescence and quantitative analysis with chemometrics-assisted excitation-emission matrix (EEM) fluorescence. Due to the significant spectral overlapping among analytes and interference, the use of the more selective time-resolved fluorescence is proposed for qualitative identification in quality control of traditional Chinese medicine (TCM) for the first time. Using the strategy of combining EEM fluorescence with second-order calibration method, i.e. parallel factor analysis (PARAFAC), the simultaneous quantification of scopoletin and scopolin in the complex system of Erycibe obtusifolia Benth was achieved successfully. The predicted concentrations were compared with the values obtained using high performance liquid chromatography-coupled to fluorimetric detector (HPLC-FLD), and no significant differences between them were observed. Therefore, the proposed methods using time-resolved fluorescence for qualitative analysis and EEMs coupled with second-order calibration for quantitative analysis in TCM are comparable and provide a suitable alternative to the chromatography-based method.

[In vivo metabolism of three coumarins from Chimonanthi Radix based on UHPLC-QTOF-MS/MS].

Scopolin (SC-1), scopoletin (SC-2) and isofraxidin (IS-1) are the main active constituents in Chimonanthi Radix. However, the in vivo metabolism of SC-1, SC-2 and IS-1 have not been comprehensively clarified. In this study, the in vivo metabolic profiles of these three coumarins in the rat plasma, urine and feces were analyzed. Ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UHPLC-QTOF-MS/MS) method was applied to characterize the prototypes and metabolites of SC-1, SC-2 and IS-1 in rat feces, urine, and plasma after intravenous administration. A total of 11 metabolites of the three parent compounds were tentatively identified. The main metabolic pathways were analyzed by identification of metabolites, and it was found that these three coumarins underwent multiple in vivo metabolic reactions including glucuronidation, sulfonation, isomerism and reduction. In this study, the analysis of metabolites of three coumarins basically demonstrated their in vivo metabolic process, providing basis for the further pharmacokinetics and pharmacological evaluations of SC-1, SC-2 and IS-1.

Accumulation of the coumarin scopolin under abiotic stress conditions is mediated by the Arabidopsis thaliana THO/TREX complex.

Secondary metabolites are involved in the plant stress response. Among these are scopolin and its active form scopoletin, which are coumarin derivatives associated with reactive oxygen species scavenging and pathogen defence. Here we show that scopolin accumulation can be induced in the root by osmotic stress and in the leaf by low-temperature stress in Arabidopsis thaliana. A genetic screen for altered scopolin levels in A. thaliana revealed a mutant compromised in scopolin accumulation in response to stress; the lesion was present in a homologue of THO1 coding for a subunit of the THO/TREX complex. The THO/TREX complex contributes to RNA silencing, supposedly by trafficking precursors of small RNAs. Mutants defective in THO, AGO1, SDS3 and RDR6 were impaired with respect to scopolin accumulation in response to stress, suggesting a mechanism based on RNA silencing such as the trans-acting small interfering RNA pathway, which requires THO/TREX function.

In vivo metabolism of three coumarins from Chimonanthi Radix based on UHPLC-QTOF-MS/MS / 中国中药杂志

Scopolin (SC-1), scopoletin (SC-2) and isofraxidin (IS-1) are the main active constituents in Chimonanthi Radix. However, the in vivo metabolism of SC-1, SC-2 and IS-1 have not been comprehensively clarified. In this study, the in vivo metabolic profiles of these three coumarins in the rat plasma, urine and feces were analyzed. Ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UHPLC-QTOF-MS/MS) method was applied to characterize the prototypes and metabolites of SC-1, SC-2 and IS-1 in rat feces, urine, and plasma after intravenous administration. A total of 11 metabolites of the three parent compounds were tentatively identified. The main metabolic pathways were analyzed by identification of metabolites, and it was found that these three coumarins underwent multiple in vivo metabolic reactions including glucuronidation, sulfonation, isomerism and reduction. In this study, the analysis of metabolites of three coumarins basically demonstrated their in vivo metabolic process, providing basis for the further pharmacokinetics and pharmacological evaluations of SC-1, SC-2 and IS-1.

Arabidopsis thaliana G2-LIKE FLAVONOID REGULATOR and BRASSINOSTEROID ENHANCED EXPRESSION1 are low-temperature regulators of flavonoid accumulation.

Flavonoid synthesis is predominantly regulated at the transcriptional level through the MYB-basic helix-loop-helix (bHLH)-WD40 (MBW) (MYB: transcription factor of the myeloblastosis protein family, WD40: tanscription factor with a short structural motif of 40 amino acids which terminates in an aspartic acid-tryptophan dipeptide) complex, and responds to both environmental and developmental stimuli. Although the developmental regulation of flavonoid accumulation in Arabidopsis thaliana has been examined in great detail, the response of the flavonoid synthesis pathway to abiotic stress (particularly low temperature) remains unclear. A screen of a Dissociation element (Ds) transposon-induced mutation collection identified two lines which exhibited an altered profile of phenylpropanoid accumulation following exposure to low-temperature stress. One of the mutated genes (BRASSINOSTEROID ENHANCED EXPRESSION1 (BEE1)) encoded a brassinosteroid enhanced expression transcription factor, while the other (G2-LIKE FLAVONOID REGULATOR (GFR)) encoded a G2-like flavonoid regulator. Phenylpropanoid-targeted analysis was performed using high-performance LC-MS, and gene expression analysis using quantitative reverse transcription-PCR. In both mutants, the accumulation of quercetins and scopolin was reduced under low-temperature growing conditions, whereas that of anthocyanin was increased. BEE1 and GFR were both shown to negatively regulate anthocyanin accumulation by inhibiting anthocyanin synthesis genes via the suppression of the bHLH (TRANSPARENT TESTA8 (TT8) and GLABROUS3 (GL3)) and/or the MYB (PRODUCTION OF ANTHOCYANIN PIGMENTS2 (PAP2)) components of the MBW complex. Our results provide new insight into the regulatory control of phenylpropanoid metabolism at low temperatures, and reveal that BEE1 and GFR act as important components of the signal transduction chain.