Alkaloid Metabolism Research Articles

Comparative Analyses of Phyllosphere Bacterial Communities and Metabolomes in Newly Developed Needles of Cunninghamia lanceolata (Lamb.) Hook. at Four Stages of Stand Growth.

Host-plant-associated bacteria affect the growth, vigor, and nutrient availability of the host plant. However, phyllosphere bacteria have received less research attention and their functions remain elusive, especially in forest ecosystems. In this study, we collected newly developed needles from sapling (age 5 years), juvenile (15 years), mature (25 years), and overmature (35 years) stands of Chinese fir [Cunninghamia lanceolata (Lamb.) Hook]. We analyzed changes in phyllosphere bacterial communities, their functional genes, and metabolic activity among different stand ages. The results showed that phyllosphere bacterial communities changed, both in relative abundance and in composition, with an increase in stand age. Community abundance predominantly changed in the orders Campylobacterales, Pseudonocardiales, Deinococcales, Gemmatimonadales, Betaproteobacteriales, Chthoniobacterales, and Propionibacteriales. Functional predictions indicated the genes of microbial communities for carbon metabolism, nitrogen metabolism, antibiotic biosynthesis, flavonoids biosynthesis, and steroid hormone biosynthesis varied; some bacteria were strongly correlated with some metabolites. A total of 112 differential metabolites, including lipids, benzenoids, and flavonoids, were identified. Trigonelline, proline, leucine, and phenylalanine concentrations increased with stand age. Flavonoids concentrations were higher in sapling stands than in other stands, but the transcript levels of genes associated with flavonoids biosynthesis in the newly developed needles of saplings were lower than those of other stands. The nutritional requirements and competition between individual trees at different growth stages shaped the phyllosphere bacterial community and host–bacteria interaction. Gene expression related to the secondary metabolism of shikimate, mevalonate, terpenoids, tocopherol, phenylpropanoids, phenols, alkaloids, carotenoids, betains, wax, and flavonoids pathways were clearly different in Chinese fir at different ages. This study provides an overview of phyllosphere bacteria, metabolism, and transcriptome in Chinese fir of different stand ages and highlights the value of an integrated approach to understand the molecular mechanisms associated with biosynthesis.

Metabolism of carcinogenic pyrrolizidine alkaloids and pyrrolizidine alkaloid N-oxides by rat primary hepatocytes generate the same characteristic DHP-DNA adducts

We recently established a genotoxic mechanism mediated by a set of (±)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP)-DNA adducts, which lead to pyrrolizidine alkaloid (PA)-induced liver tumor initiation. This mechanism is involved in the metabolism of a series of carcinogenic PAs and PA N-oxides in rats in vivo and in vitro. There is a correlation between the order of liver tumor potency and the level of DHP-DNA adduct formation. Thus, these DHP-DNA adducts can be potential biomarkers of PA and PA N-oxide exposure and liver tumor initiation. To establish the generality of this mechanism, in the present study, we examined the metabolism of 13 potential carcinogenic PAs, 1 non-carcinogenic PA, and 5 PA N-oxides by male rat primary hepatocytes. With the exception of the nontoxic PA and vehicle control, all treated groups produced identical set of DHP-DNA adducts. These results support a general genotoxic mechanism mediated by the formation of characteristic DHP-DNA adducts leading to PA-induced liver tumor initiation.

In vitro Metabolism of Humantenine in Liver Microsomes from Human, Pig, Goat and Rat.

Gelsemium elegans Benth (G. elegans) is a well-known toxic plant. Alkaloids are the main active components of G. elegans. Currently, the metabolism of several alkaloids, such as gelsenicine, koumine, and gelsemine, has been widely studied. However, as one of the most important alkaloids in G. elegans, the metabolism of humantenine has not been studied yet. In order to elaborate on the in vitro metabolism of humantenine, a comparative analysis of its metabolic profile in human, pig, goat and rat liver microsomes was carried out using high performance chromatography/ quadrupole time-of-flight mass spectrometry (HPLC/QqTOF-MS) for the first time. Totally, ten metabolites of humantenine were identified in liver microsomes from human (HLMs), pig (PLMs), goat (GLMs) and rat (RLMs) based on the accurate MS/MS spectra. Five metabolic pathways of humantenine, including demethylation, dehydrogenation, oxidation, dehydrogenation and oxidation, and demethylation and oxidation, were proposed in this study. There were qualitative and quantitative species differences in the metabolism of humantenine among the four species. The in vitro metabolism of humantenine in HLMs, PLMs, GLMs and RLMs was studied by a sensitive and specific detection method based on HPLC/QqTOF-MS. The results indicated that there were species-related differences in the metabolism of humantenine. This work might be of great significance for the further research and explanation of species differences in terms of toxicological effects of G. elegans.

Structural insights into the mechanisms of substrate recognition and catalysis for the N-methyltransferases involved in benzylisoquinoline alkaloid metabolism

Structural insights into the mechanisms of substrate recognition and catalysis for the <i>N</i>-methyltransferases involved in benzylisoquinoline alkaloid metabolism

Properties, Pharmacology, and Pharmacokinetics of Active Indole and Oxindole Alkaloids in Uncaria Hook.

Uncaria Hook (UH) is a dry stem with hook of Ucaria plant and is contained in Traditional Japanese and Chinese medicine such as yokukansan, yokukansankachimpihange, chotosan, Gouteng-Baitouweng, and Tianma-Gouteng Yin. UH contains active indole and oxindole alkaloids and has the therapeutic effects on ailments of the cardiovascular and central nervous systems. The recent advances of analytical technology led to reports of detailed pharmacokinetics of UH alkaloids. These observations of pharmacokinetics are extremely important for understanding the treatment’s pharmacological activity, efficacy, and safety. This review describes properties, pharmacology, and the recently accumulated pharmacokinetic findings of UH alkaloids, and discusses challenges and future prospects. UH contains major indole and oxindole alkaloids such as corynoxeine, isocorynoxeine, rhynchophylline, isorhynchophylline, hirsuteine, hirsutine, and geissoschizine methyl ether (GM). These alkaloids exert neuroprotective effects against Alzheimer’s disease, Parkinson’s disease, and depression, and the mechanisms of these effects include anti-oxidant, anti-inflammatory, and neuromodulatory activities. Among the UH alkaloids, GM exhibits comparatively potent pharmacological activity (e.g., agonist activity at 5-HT1A receptors). UH alkaloids are absorbed into the blood circulation and rapidly eliminated when orally administered. UH alkaloids are predominantly metabolized by Cytochrome P450 (CYP) and converted into various metabolites, including oxidized and demethylated forms. Regarding GM metabolism by CYPs, a gender-dependent difference is observed in rats but not in humans. Several alkaloids are detected in the brain after passing through the blood–brain barrier in rats upon orally administered. GM is uniformly distributed in the brain and binds to various channels and receptors such as the 5-HT receptor. By reviewing the pharmacokinetics of UH alkaloids, challenges were found, such as differences in pharmacokinetics between pure drug and crude drug products administration, food-influenced absorption, metabolite excretion profile, and intestinal tissue metabolism of UH alkaloids. This review will provide readers with a better understanding of the pharmacokinetics of UH alkaloids and their future challenges, and will be helpful for further research on UH alkaloids and crude drug products containing UH.

Cytochrome P450 Enzymes as Key Drivers of Alkaloid Chemical Diversification in Plants.

Plants produce more than 20,000 nitrogen-containing heterocyclic metabolites called alkaloids. These chemicals serve numerous eco-physiological functions in the plants as well as medicines and psychedelic drugs for human for thousands of years, with the anti-cancer agent vinblastine and the painkiller morphine as the best-known examples. Cytochrome P450 monooxygenases (P450s) play a key role in generating the structural variety that underlies this functional diversity of alkaloids. Most alkaloid molecules are heavily oxygenated thanks to P450 enzymes’ activities. Moreover, the formation and re-arrangement of alkaloid scaffolds such as ring formation, expansion, and breakage that contribute to their structural diversity and bioactivity are mainly catalyzed by P450s. The fast-expanding genomics and transcriptomics databases of plants have accelerated the investigation of alkaloid metabolism and many players behind the complexity and uniqueness of alkaloid biosynthetic pathways. Here we discuss recent discoveries of P450s involved in the chemical diversification of alkaloids and how these inform our approaches in understanding plant evolution and producing plant-derived drugs.

Metabolic profiling of liver and faeces in mice infected with echinococcosis

BackgroundEchinococcosis is a severe zoonotic parasitic disease which severely affects the health of the hosts. The diagnosis of echinococcosis depends mainly on imaging examination. However, the patient is often in the late stage of the disease when the symptoms appear, thus limiting the early diagnosis of echinococcosis. The treatment and prognosis of the patients are hampered because of long-term asymptomatic latency. Metabolomics is a new discipline developed in the late 1990s. It reflects a series of biological responses in pathophysiological processes by demonstrating the changes in metabolism under the influence of internal and external factors. When the organism is invaded by pathogens, the alteration in the characteristics of metabolites in cells becomes extremely sensitive. Here, we used a metabolomics approach involving liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) to determine the molecular mechanism of cystic echinococcosis (CE) and to develop an effective method for CE diagnosis.MethodsTwenty 8-week-old female BALB/c mice were divided into normal and Echinococcus granulosus infection groups. To develop the E. granulosus infection model, mice were infected with protoscoleces. Six weeks later, the abdomens of the mice showed significant bulging. An LC–MS/MS system-based metabolomics approach was used to analyse the liver and faeces to reveal the metabolic profiles of mice with echinococcosis.ResultsWe found that the metabolism of nucleotides, alkaloids, amino acids, amides, and organic acids in mice is closely interrelated with E. granulosus infection. In the liver, the metabolic pathways of tyrosine and tryptophan biosynthesis; phenylalanine, valine, leucine and isoleucine biosynthesis; and phenylalanine metabolism were notably associated with the occurrence and development of hydatid disease, and in the faeces, pantothenate and CoA biosynthesis are thought to be closely associated with the development of CE.ConclusionThe metabolomics approach used in this study provides a reference for a highly sensitive and specific diagnostic and screening method for echinococcosis.Graphical

Evaluation of CYP2D, CYP1A2 and distribution of tetrandrine, fangchinoline in the brain, liver, and kidney of wistar rats after short-term exposure to Cyclea peltata

Background: Cyclea peltata (CP) roots are used in Indian traditional medicine to treat various diseases. However, short-term toxic effects of CP are completely unknown. Objectives: The aim of this study is to evaluate short-term toxic effects of CP, tissue distribution of bioactive alkaloids tetrandrine, fangchinoline in the brain, liver, kidney, and mRNA expression of CYP2D, CYP1A2 after CP administration. Materials and Methods: In vitro toxicity evaluation of CP was carried out using annexin 5/propidium iodide assay with or without CP treatment in L 929 cell line. And in vivo short term toxicity of CP was evaluated in Wistar rats for 28 days. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) based tissue distribution of bioactive molecules was assessed and mRNA expression of CYP1A2, CYP2D, CYP2C6, and CYP2E1 were estimated using qRT- polymerase chain reaction. Results: In vitro toxicity of 70% aqueous ethanol extract of CP 50 μg/mL showed 62.18% cell viability. Oral administration of CP (50, 500 mg/kg) did not cause any clinical, hematological, serum biochemical, and histopathological changes in rats, whereas CP (1000 mg/kg) showed infiltrative changes in the kidney and lungs. Imbalance in oxidative stress and antioxidant defense was reflected as elevated MDA levels in rat liver. LC-Q-TOF-MS studies could detect tissue distribution of bioactive alkaloids tetrandrine, fangchinoline and their decomposed masses in the liver and kidney, whereas tetrandrine and its decomposed molecule (580.3) ([M + H]-43) + could cross blood–brain barrier and were detected in the brain. Evaluation of mRNA expression revealed dose-dependent increase in expression of CYP2D and CYP1A2. Conclusion: Oral administration of CP 500 mg/kg for 28 days is safer in rats due to balanced antioxidant defense. Imbalance in antioxidant defense enzymes and toxic metabolites formed through the escalation of CYP2D, CYP1A2 and metabolism of bioactive alkaloids of CP may be the reason for infiltrative changes in kidney, lungs observed after 28 days CP 1000 mg/kg administration.

Effects of gut microbiota on five absorbed components of Berberis kansuensis in rat serum by HPLC-QqQ-MS

To elucidate the absorption and metabolism of alkaloids in Berberis kansuensis in vivo, a high performance liquid chromatography-triple quadrupole mass spectrometry(HPLC-QqQ-MS) method was developed to qualitatively and quantitatively analyze the absorption components in rat serum in multiple-reaction monitoring mode. The mobile phase consisted of 0.1% formic acid and acetonitrile with a gradient elution mode. In addition, to investigate the effects of gut microbiota on five absorbed components of B. kansuensis in rat serum, diabetic rat and pseudo germ-free diabetic rat models were established, and partial least squares discriminant analysis and One-way ANOVA were used to study the content differences of five components among different groups. In this study, a HPLC-QqQ-MS method for quantitative analysis of five components in rat serum after oral administration of B. kansuensis was established for the first time. It was found that there were differences in the five constituents in rat serum between different groups. By comparing the normal group with the diabetic model group, we found that the absorption and metabolism capacities of berberine and magnoflorine were different under the health and pathological conditions. It was also found that the serum levels of berberine, magnoflorine and jatrorrhizine in pseudo germ-free diabetic rats were significantly lower than those in diabetic rats, indicating that gut microbiota plays an important role in the metabolism of alkaloids of B. kansuensis in vivo. These results provide a good reference for clarifying the active ingredients of B. kansuensis in the treatment of diabetes.

In vitro metabolism of pyrrolizidine alkaloids – Metabolic degradation and GSH conjugate formation of different structure types

Pyrrolizidine alkaloid (PA) forming plants are found worldwide and may contaminate food products at levels being of concern for human health. Due to the high biodiversity of PA producing plants many different types of PA structures are formed. PAs themselves are not toxic but require metabolic activation to exert toxicity.To investigate if the structure of the PAs affects their in vitro metabolism, we incubated a set of 22 PAs and compared the degradation rates and the amount of formed glutathione (GSH) conjugates. With human liver microsomes, no metabolic degradation of monoesters was found. Degradation rates of diester PAs tended to correlate with their hydrophilicity, whereby the more polar and branched-chained PAs exhibited lower degradation. There was a trend towards higher degradation rates in the presence of rat liver microsomes, but the GSH conjugate levels were similar. Although an effective degradation seems to be related with high GSH conjugate levels, no clear correlation between both parameters could be deduced. For both species no GSH conjugates, or only trace amounts, were formed from monoesters. However, for both open-chained as well as cyclic diesters GSH conjugates were detected and determined levels were comparable for both ester types without major structure-dependent differences.

In sito galanthamine extraction during the cultivation of Leucojum aestivum L. shoot culture in two-phase bubble column cultivation system.

Two‐phase bioreactor cultivation system was developed and applied for in sito recovery of extracellular galanthamine during the cultivation of Leucojum aestivum L. shoot culture in a modified column bioreactor system. The inclusion of an external circulation column with adsorbent resin Amberlite XAD‐4 as a second phase, on the 21st day of the beginning of cultivation resulted in 1.25 folds increase in biomass accumulation and maximal amounts of accumulated galanthamine of 6 mg/L (3.1 mg/L intracellular and 2.9 mg/L extracellular). It was demonstrated that the inclusion of a second phase at the cultivation of the L. aestivum shoot culture in a bubble column bioreactor with internal sections redirected the alkaloid metabolism to galanthamine synthesis and inhibits the synthesis of hemanthamine and lycorine type alkaloids. Our research demonstrated that the application of the two‐phase cultivation systems could be an important tool to increase the yields of valuable secondary metabolites in plant tissue culture‐based bioprocess.

Whole-genome sequencing and analysis of the Chinese herbal plant Gelsemium elegans

BackgroundGelsemium elegans (G. elegans) (2n = 2x = 16) is genus of flowering plants belonging to the Gelsemicaeae family. MethodHere, a high-quality genome assembly using the Oxford Nanopore Technologies (ONT) platform and high-throughput chromosome conformation capture techniques (Hi-C) were used. ResultsA total of 56.11 Gb of raw GridION X5 platform ONT reads (6.23 Gb per cell) were generated. After filtering, 53.45 Gb of clean reads were obtained, giving 160 × coverage depth. The de novo genome assemblies 335.13 Mb, close to the 338 Mb estimated by k-mer analysis, was generated with contig N50 of 10.23 Mb. The vast majority (99.2%) of the G. elegans assembled sequence was anchored onto 8 pseudo-chromosomes. The genome completeness was then evaluated and 1338 of the 1440 conserved genes (92.9%) could be found in the assembly. Genome annotation revealed that 43.16% of the G. elegans genome is composed of repetitive elements and 23.9% is composed of long terminal repeat elements. We predicted 26,768 protein-coding genes, of which 84.56% were functionally annotated. ConclusionThe genomic sequences of G. elegans could be a valuable source for comparative genomic analysis in the Gelsemicaeae family and will be useful for understanding the phylogenetic relationships of the indole alkaloid metabolism.

The Metabolism and Disposition of Koumine, Gelsemine and Humantenmine from Gelsemium.

Gelsemium is a toxic flowering plant of the Gelsemiaceae family. It is used to treat skin diseases in China, and it is an important medicinal and homeopathic plant in North America. Up to now, more than 200 compounds have been isolated and reported from Gelsemium. More than 120 of these are indole alkaloids, including the main components, koumine, gelsemine and humantenmine which produce the pharmacological and toxicological effects of Gelsemium. However, their clinical application their limited by its narrow therapeutic window. Therefore, it is very important to study the metabolism and disposition of indole alkaloids from Gelsemium before their clinical application. This paper reviews all the reports on the metabolism and disposition of alkaloids isolated from Gelsemium at home and abroad. The metabolism and disposition of alkaloids from Gelsemium were searched by the Web of Science, NCBI, PubMed and some Chinese literature databases. Only koumine, gelsemine and humantenmine have been reported, and few other alkaloids have been described. These studies indicated that the three indole alkaloids are absorbed rapidly, widely distributed in tissues, extensively metabolized and rapidly eliminated. There are species differences in the metabolism of these alkaloids, which is the reason for the differences in their toxicity in animals and humans. This review not only explains the pharmacokinetics of indole alkaloids from Gelsemium but also facilitates further study on their metabolism and mechanism of toxicity.

Ethylene response factor NtERF91 positively regulates alkaloid accumulations in tobacco (Nicotiana tabacum L.)

Tobacco alkaloid metabolism is regulated by various transcription factors (TFs). Here, we have characterized a non-NIC2 locus gene, Ethylene Response Factor 91 (ERF91), function in regulation of alkaloid accumulation in tobacco. NtERF91 was preferentially expressed in roots and induced by jasmonic acid. Additionally, NtERF91 was able to in vitro bind to the NtPMT2 and NtQPT2 promoters via directly targeting the GCC-box elements and transactivate NtQPT2 gene expression. Ectopic overexpression of NtERF91 not only increased the expression of most nicotine biosynthetic genes, but also altered alkaloid accumulation profile, resulting in dramatically anatabine accumulation. We conclude that NtERF91 plays an overlapped but distinct role in regulating tobacco alkaloid accumulations.

Untargeted GC-TOFMS-based cellular metabolism analysis to evaluate ozone degradation effect of deoxynivalenol

Ozone plays an increasingly important role in food processing for its antimicrobial ability and degradation effects on mycotoxins. The mycotoxin deoxynivalenol (DON) was treated with saturated aqueous ozone for different amounts of time, and by-products were collected for compounds annotation and cytotoxicity evaluation. To investigate the cytotoxicity of ozone degradation by-products, untargeted GC-TOFMS-based metabolomics were utilized. Caco-2 cells were dosed with 0.1 μg/mL DON and saturated aqueous ozone-treated DON (treatment time: 1 min, 3 min, 5 min) for 24 h followed by cytotoxicity tests (cell viability assay, ROS assay, and apoptosis assay), and intracellular metabolic analysis. Cytotoxicity test results revealed that ozone treatment could degrade DON structure; however, its degradation products and cellular toxicity existed under different treatment time of ozone. Metabolomics analysis indicated that ozone-treated DON degradation products weakened DON-induced metabolic disorder, such as purines-related nucleotide metabolism; Krebs cycle-related fuel and energy metabolism; and lipid, alkaloid and amino acid metabolism. By contrast, the catecholamine pathway, which is related to latent inflammation and oxidative stress effects, was unaltered in the ozone-treated DON group, indicating that the potential cytotoxicity still existed. These findings provide a comprehensive safety evaluation for ozone-treated DON in vitro and propose a new strategy for studying the effects of ozone-treated food.

Comparative transcriptomic analysis reveal the regulation mechanism underlying MeJA-induced accumulation of alkaloids in Dendrobium officinale.

Dendrobium officinale is a traditional medicinal herb with a variety of bioactive components. Alkaloid is one of the major active ingredients of Dendrobium plants, and its immune regulatory effects have been well-studied. Although a number of genes involved in the biosynthetic pathway of alkaloids have been elucidated, the regulation mechanism underlying the methyl-jasmonate (MeJA)-induced accumulation of alkaloids in D. officinale is largely unknown. In our study, a total of 4,857 DEGs, including 2,943 up- and 1,932 down-regulated genes, were identified between the control and MeJA-treated groups. Kyoto Encyclopedia of Genes and Genomes annotation showed that a number of DEGs were associated with the putative alkaloid biosynthetic pathway in D. officinale. The main group of Dendrobium alkaloids are sesquiterpene alkaloids, which are the downstream products of mevalonate (MVA) and methylerythritol 4-phosphate (MEP) pathway. Several MVA and MEP pathway genes were significantly up-regulated by the MeJA treatment, suggesting an active precursor supply for the alkaloid biosynthesis under MeJA treatment. A number of MeJA-induced P450 family genes, aminotransferase genes and methyltransferase genes were identified, providing several important candidates to further elucidate the sesquiterpene alkaloid biosynthetic pathway of D. officinale. Furthermore, a large number of MeJA-induced transcript factor encoding genes were identified, suggesting a complex genetic network affecting the sesquiterpene alkaloid metabolism in D. officinale. Our data aids to reveal the regulation mechanism underlying the MeJA-induced accumulation of sesquiterpene alkaloids in D. officinale.

Panax ginseng Inhibits Metabolism of Diester Alkaloids by Downregulating CYP3A4 Enzyme Activity via the Pregnane X Receptor.

To investigate the effects of P. ginseng C.A. Mey (P. ginseng) on the metabolism of diester alkaloids and explore the potential mechanism. P. ginseng was administered orally to rats for 7 days, after which liver microsome samples were prepared and then incubated with diester alkaloids. Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry was used to determinate the concentration of diester alkaloids to calculate the clearance rate. The cocktail method was used to evaluate the effects of oral administration of P. ginseng extracts on the activities of cytochrome P450 (CYP) isoforms in rats through the changes in the pharmacokinetic parameters of the probe drugs. The protein and gene expression of CYP3A2 and pregnane X receptor (PXR) in rats were evaluated by western blotting and quantitative PCR. The specific enzyme inhibitor method and human recombinant enzyme method were used to identify the involvement of sub-CYPs in the metabolism of diester alkaloids in human liver microsomes (HLMs). The clearances of aconitine, mesaconitine, and hypaconitine in the P. ginseng groups were lower than those of the control group. The areas under the curve of midazolam were 2.37 ± 1.05, 4.96 ± 0.51, and 6.23 ± 1.30 mg·L−1·h for the low-, medium-, and high-dose P. ginseng groups, respectively, which were higher than that of the control (2.23 ± 0.64 mg·L−1·h). The clearances of midazolam for the medium- (1.87 ± 0.16 L·h−1·kg−1) and high-dose (1.60 ± 0.34 L·h−1·kg−1) P. ginseng groups were lower than that of the control group (4.66 ± 1.43 L·h−1·kg−1). After exposure to P. ginseng extracts, the gene and protein expression levels of CYP3A4 and PXR were decreased. The hepatic metabolism rates of aconitine, mesaconitine, and hypaconitine in HLMs were decreased to 60.37%, 21.67%, and 10.11%, respectively, when incubated with ketoconazole, a specific inhibitor for CYP3A. The kinetic plots indicated that the KM and Vmax values of CYP3A4 were 10.08 ± 3.26 μM and 0.12 ± 0.01nmol·mg protein−1·min−1 for aconitine, 131.3 ± 99.75 μM and 0.73 ± 0.44 nmol·mg protein−1·min−1 for mesaconitine, and 17.05 ± 9.70 μM and 0.16 ± 0.04 nmol·mg protein−1·min−1 for hypaconitine, respectively. The in vitro mean intrinsic clearance rates by CYP3A4 were 0.0119, 0.0056, and 0.0091 mL·nmol CYP−1·min−1 for aconitine, mesaconitine, and hypaconitine, respectively. Therefore we implied that P. ginseng inhibited the metabolism of diester alkaloids in vitro and decreased the CYP3A4 enzyme activity as well as the gene and protein expression of CYP3A4 and PXR in vivo. CYP3A4 had a larger effect on diester alkaloid metabolism than the other human CYP isoforms, CYP1A2, CYP2C9, and CYP2E1.

Comparative study on the metabolism of the ergot alkaloids ergocristine, ergocryptine, ergotamine, and ergovaline in equine and human S9 fractions and equine liver preparations

1. Ergopeptine alkaloids like ergovaline and ergotamine are suspected to be associated with fescue toxicosis and ergotism in horses. Information on the metabolism of ergot alkaloids is scarce, especially in horses, but needed for toxicological analysis of these drugs in urine/feces of affected horses. The aim of this study was to investigate the metabolism of ergovaline, ergotamine, ergocristine, and ergocryptine in horses and comparison to humans.2. Supernatants of alkaloid incubations with equine and human liver S9 fractions were analyzed by reversed-phase liquid-chromatography coupled to high-resolution tandem mass spectrometry with full scan and MS2 acquisition. Metabolite structures were postulated based on their MS2 spectra in comparison to those of the parent alkaloids. All compounds were extensively metabolized yielding nor-, N-oxide, hydroxy and dihydro-diole metabolites with largely overlapping patterns in equine and human liver S9 fractions. However, some metabolic steps e.g. the formation of 8′-hydroxy metabolites were unique for human metabolism, while formation of the 13/14-hydroxy and 13,14-dihydro-diol metabolites were unique for equine metabolism. Incubations with equine whole liver preparations yielded less metabolites than the S9 fractions.3. The acquired data can be used to develop metabolite-based screenings for these alkaloids, which will likely extend their detection windows in urine/feces from affected horses.

Profiling of indole metabolic pathway in thermo-sensitive Bainong male sterile line in wheat (Triticum aestivum L.).

Bainong male sterile (BNS) wheat (Triticum aestivum L.) is a thermo-sensitive genic male sterile line with excellent sterility and self-restoration. We focused on transcriptional profiles of differentially expressed probes between BNS sterile and fertile anthers. Anthers, rachis and spikes from sterile line and fertile line were collected. Extracted RNA was assayed using wheat expression microarray and Gene Ontology was analyzed using Cytoscape with ClueGO. An indole (indole-3-acetic acid: IAA) metabolism pathway sub-network was almost formed in all differentially expressed profiles between sterile and fertile samples. IAA sub-network contained four nodes of indole and alkaloid metabolism connecting main network via indole compounds. This sub-network was absent in rachis and intact in transformed fertile anthers, which was the main differently expressed metabolism pathway in F1 anthers with restorer genes. Alkaloid metabolism was absent in sterile anthers. Abnormal metabolism of IAA may be involved in BNS sterility. BNS transformation may be regulated by the production of IAA and alkaloid metabolism pathway, which favor the safe utilization of the sterile line in hybrid wheat production.

Effects of methyl jasmonate on metabolism of topical alkaloids and expression of relate genes in Atropa belladonna

Hyoscyamine and scopolamine are important secondary metabolites of tropane alkaloid in Atropa belladonna with pharmacological values in many aspects.In this study, the seedlings of A.belladonna were planted by soil culture and treated with different concentrations of methyl jasmonate (MeJA). The contents of hyoscyamine and scopolamine,the upstream products in alkaloid synthesis,and the expression levels of key enzyme genes PMT, TR Ⅰ and H6H in secondary metabolites of A. belladonna seedlings were measured to clarify the mechanism of MeJA regulating alkaloids synthesis.The results showed that MeJA(200 μmol·L⁻¹) treatment was more favorable for the accumulation of alkaloids.The content of putrescine was almost consistent with the change of key enzymes activities in the synthesis of putrescine,the both increased first and then decreased with the increased MeJA concentration and the content of putrescine reached the highest at 200 μmol·L⁻¹ MeJA.Further detection of gene expression of PMT, TR Ⅰ and H6H in TAs synthesis pathway showed that no significant trend in PMT gene expression levels.The expression levels of TR Ⅰ and H6H in leaves and roots under 200 μmol·L⁻¹ MeJA were the highest.It can be speculated that the regulation of the formation of hyoscyamine and scopolamine by MeJA mainly through affecting the expression of key enzyme genes.Appropriate concentration of MeJA increased the gene expression of TR Ⅰ in both leaves and roots as well as H6H in roots,promoting the accumulation of alkaloids and the conversion of hyoscyamine to scopolamine.