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Zhengtao Wang - One of the best experts on this subject based on the ideXlab platform.
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mass spectrometry directed analysis and purification of Pyrrolizidine Alkaloid cis trans isomers in gynura japonica
IEEE Journal of Solid-state Circuits, 2014Co-Authors: Lianxiang Fang, Aizhen Xiong, Xiao Yang, Wenzhi Cheng, Li Yang, Zhengtao WangAbstract:Pyrrolizidine Alkaloids are highly hepatotoxic natural chemicals that produce irreversible chronic and acute hepatotoxic effects on human beings. Purification of large amounts of Pyrrolizidine Alkaloids is necessary for toxicity studies. In this study, an efficient method for targeted analysis and purification of Pyrrolizidine Alkaloid cis/trans isomers from herbal materials was developed for the first time. Targeted analysis of the hepatotoxic Pyrrolizidine Alkaloids was performed by liquid chromatography with tandem mass spectrometry (precursor ion scan and daughter ion scan), and the purification of Pyrrolizidine Alkaloids was achieved with a mass-directed auto purification system. The extraction and preparative liquid chromatography conditions were optimized. The developed method was applied to analysis of Gynura japonica (Thunb.) Juel., a herbal medicine traditionally used for detumescence and relieving pain but is potentially hepatotoxic as it contains Pyrrolizidine Alkaloids. Twelve Pyrrolizidine Alkaloids (six cis/trans isomer pairs) were identified with reference compounds or characterized by liquid chromatography with tandem mass spectrometry, and five individual Pyrrolizidine Alkaloids, including (E)-seneciphylline, seneciphylline, integerrimine, senecionine, and seneciphyllinine, were prepared from G. japonica roots with high efficiency. The results of this work provide a new technique for the preparation of large amounts of Pyrrolizidine Alkaloid reference substances, which will also benefit toxicological studies of Pyrrolizidine Alkaloids and treatments for Pyrrolizidine Alkaloid-induced toxicity.
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Mass-spectrometry-directed analysis and purification of Pyrrolizidine Alkaloid cis/trans isomers in Gynura japonica.
IEEE Journal of Solid-state Circuits, 2014Co-Authors: Lianxiang Fang, Aizhen Xiong, Xiao Yang, Wenzhi Cheng, Li Yang, Zhengtao WangAbstract:Pyrrolizidine Alkaloids are highly hepatotoxic natural chemicals that produce irreversible chronic and acute hepatotoxic effects on human beings. Purification of large amounts of Pyrrolizidine Alkaloids is necessary for toxicity studies. In this study, an efficient method for targeted analysis and purification of Pyrrolizidine Alkaloid cis/trans isomers from herbal materials was developed for the first time. Targeted analysis of the hepatotoxic Pyrrolizidine Alkaloids was performed by liquid chromatography with tandem mass spectrometry (precursor ion scan and daughter ion scan), and the purification of Pyrrolizidine Alkaloids was achieved with a mass-directed auto purification system. The extraction and preparative liquid chromatography conditions were optimized. The developed method was applied to analysis of Gynura japonica (Thunb.) Juel., a herbal medicine traditionally used for detumescence and relieving pain but is potentially hepatotoxic as it contains Pyrrolizidine Alkaloids. Twelve Pyrrolizidine Alkaloids (six cis/trans isomer pairs) were identified with reference compounds or characterized by liquid chromatography with tandem mass spectrometry, and five individual Pyrrolizidine Alkaloids, including (E)-seneciphylline, seneciphylline, integerrimine, senecionine, and seneciphyllinine, were prepared from G. japonica roots with high efficiency. The results of this work provide a new technique for the preparation of large amounts of Pyrrolizidine Alkaloid reference substances, which will also benefit toxicological studies of Pyrrolizidine Alkaloids and treatments for Pyrrolizidine Alkaloid-induced toxicity.
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quercetin prevents Pyrrolizidine Alkaloid clivorine induced liver injury in mice by elevating body defense capacity
PLOS ONE, 2014Co-Authors: Zaiyong Wang, Zhunxiu Cai, Chun Pang, Zhengtao WangAbstract:Quercetin is a plant-derived flavonoid that is widely distributed in nature. The present study is designed to analyze the underlying mechanism in the protection of quercetin against Pyrrolizidine Alkaloid clivorine-induced acute liver injury in vivo. Serum transaminases, total bilirubin analysis, and liver histological evaluation demonstrated the protection of quercetin against clivorine-induced liver injury. Terminal dUTP nick end-labeling assay demonstrated that quercetin reduced the increased amount of liver apoptotic cells induced by clivorine. Western-blot analysis of caspase-3 showed that quercetin inhibited the cleaved activation of caspase-3 induced by clivorine. Results also showed that quercetin reduced the increase in liver glutathione and lipid peroxidative product malondialdehyde induced by clivorine. Quercetin reduced the enhanced liver immunohistochemical staining for 4-hydroxynonenal induced by clivorine. Results of the Mouse Stress and Toxicity PathwayFinder RT2 Profiler PCR Array demonstrated that the expression of genes related with oxidative or metabolic stress and heat shock was obviously altered after quercetin treatment. Some of the alterations were confirmed by real-time PCR. Our results demonstrated that quercetin prevents clivorine-induced acute liver injury in vivo by inhibiting apoptotic cell death and ameliorating oxidative stress injury. This protection may be caused by the elevation of the body defense capacity induced by quercetin.
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identification of metabolites of adonifoline a hepatotoxic Pyrrolizidine Alkaloid by liquid chromatography tandem and high resolution mass spectrometry
Rapid Communications in Mass Spectrometry, 2009Co-Authors: Aizhen Xiong, Li Yang, Fang Zhang, Jun Wang, Han Han, Changhong Wang, S Annie W Bligh, Zhengtao WangAbstract:Hepatotoxic Pyrrolizidine Alkaloid (HPA)-containing plants have always been a threat to human and livestock health worldwide. Adonifoline, a main HPA in Senecio scandens Buch.-Ham. ex D. Don (Qianli guang), was used officially as an infusion in cases of oral and pharyngeal infections in China. In this study in vivo metabolism of adonifoline was studied for the first time by identifying the metabolites of adonifoline present in bile, urine and feces of rats using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MSn) (ion trap) as well as liquid chromatography/electrospray ionization high-resolution mass spectrometry (LC/ESI-HRMS) (quadrupole-time of flight). In total 19 metabolites were identified and, among them, retronecine-N-oxides were confirmed by matching their fragmentation patterns with their fully characterized synthetic compounds. These metabolites are all involved in both phase I and phase II metabolic processes and the principal in vivo metabolism pathways of adonifoline were proposed.
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protective mechanisms of n acetyl cysteine against Pyrrolizidine Alkaloid clivorine induced hepatotoxicity
Journal of Cellular Biochemistry, 2009Co-Authors: Tianyu Liu, Ying Chen, Zhengtao WangAbstract:Pyrrolizidine Alkaloid (PA) clivorine, isolated from traditional Chinese medicinal plant Ligularia hodgsonii Hook, has been shown to induce apoptosis in hepatocytes via mitochondrial-mediated apoptotic pathway in our previous research. The present study was designed to observe the protection of N-acetyl-cysteine (NAC) on clivorine-induced hepatocytes apoptosis. Our results showed that 5 mM NAC significantly reversed clivorine-induced cytotoxicity via MTT and Trypan Blue staining assay. DNA apoptotic fragmentation analysis and Western-blot results showed that NAC decreased clivorine-induced apoptotic DNA ladder and caspase-3 activation. Further results showed that NAC inhibited clivorine-induced Bcl-xL decrease, mitochondrial cytochrome c release and caspase-9 activation. Intracellular glutathione (GSH) is an important ubiquitous redox-active reducing sulfhydryl (‐SH) tripeptide, and our results showed that clivorine (50 mM) decreased cellular GSH amounts and the ratio of GSH/GSSG in the time-dependent manner, while 5 mM NAC obviously reversed this depletion. Further results showed that GSH synthesis inhibitor BSO augmented clivorine-induced cytotoxicity, while exogenous GSH reversed its cytotoxicity on hepatocytes. Clivorine (50 mM) significantly induced cellular reactive oxygen species (ROS) generation. Further results showed that 50 mM Clivorine decreased glutathione peroxidase (GPx) activity and increased glutathione S transferase (GST) activity, which are both GSH-related antioxidant enzymes. Thioredoxin-1 (Trx) is also a ubiquitous redox-active reducing (‐SH) protein, and clivorine (50 mM) decreased cellular expression of Trx in a time-dependent manner, while 5 mM NAC reversed this decrease. Taken together, our results demonstrate that the protection of NAC is major via maintaining cellular reduced environment and thus prevents clivorine-induced mitochondrial-mediated hepatocytes apoptosis. J. Cell. Biochem. 108: 424‐432, 2009. 2009 Wiley-Liss, Inc.
Peter G L Klinkhamer - One of the best experts on this subject based on the ideXlab platform.
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Pyrrolizidine Alkaloid variation in shoots and roots of segregating hybrids between jacobaea vulgaris and jacobaea aquatica
New Phytologist, 2011Co-Authors: Klaas Vrieling, Dandan Cheng, Heather Kirk, Patrick P J Mulder, Peter G L KlinkhamerAbstract:Hybridization can lead to novel qualitative or quantitative variation of secondary metabolite (SM) expression that can have ecological and evolutionary consequences. We measured Pyrrolizidine Alkaloid (PA) expression in the shoots and roots of a family including one Jacobaea vulgaris genotype and one Jacobaea aquatica genotype (parental genotypes), two F(1) hybrid genotypes, and 102 F(2) hybrid genotypes using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We detected 37 PAs in the roots and shoots of J. vulgaris, J. aquatica and the hybrids. PA concentrations and compositions differed between genotypes, and between roots and shoots. Three otosenine-like PAs that only occurred in the shoots of parental genotypes were present in the roots of F(2) hybrids; PA compositions were sometimes novel in F(2) hybrids compared with parental genotypes, and in some cases transgressive PA expression occurred. We also found that PAs from within structural groups covaried both in the roots and in the shoots, and that PA expression was correlated between shoots and roots. Considerable and novel variation present among F(2) hybrids indicates that hybridization has a potential role in the evolution of PA diversity in the genus Jacobaea, and this hybrid system is useful for studying the genetic control of PA expression.
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species by environment interactions affect Pyrrolizidine Alkaloid expression in senecio jacobaea senecio aquaticus and their hybrids
Journal of Chemical Ecology, 2010Co-Authors: Heather Kirk, Klaas Vrieling, Eddy Van Der Meijden, Peter G L KlinkhamerAbstract:We examined the effects of water and nutrient availability on the expression of the defense Pyrrolizidine Alkaloids (PAs) in Senecio jacobaea and S. aquaticus. Senecio jacobaea, and S. aquaticus are adapted to different natural habitats, characterized by differing abiotic conditions and different selection pressures from natural enemies. We tested if PA concentration and diversity are plastic over a range of water and nutrient treatments, and also whether such plasticity is dependent on plant species. We also tested the hypothesis that hybridization may contribute to PA diversity within plants, by comparing PA expression in parental species to that in artificially generated F1 hybrids, and also in later generation natural hybrids between S. jacobaea and S. aquaticus. We showed that total PA concentration in roots and shoots is not dependent on species, but that species determines the pattern of PA diversification. Pyrrolizidine Alkaloid diversity and concentration are both dependent on environmental factors. Hybrids produce a putatively novel PA, and this PA is conserved in natural hybrids, that are backcrossed to S. jacobaea. Natural hybrids that are backcrossed several times to S. jacobaea are with regard to PA diversity significantly different from S. jacobaea but not from S. aquaticus, while F1 hybrids are in all cases more similar to S. jacobaea. These results collectively suggest that PA diversity is under the influence of natural selection.
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variation in Pyrrolizidine Alkaloid patterns of senecio jacobaea
Phytochemistry, 2004Co-Authors: Mirka Macel, Klaas Vrieling, Peter G L KlinkhamerAbstract:We studied the variation in Pyrrolizidine Alkaloid (PA) patterns of lab-grown vegetative plants of 11 European Senecio jacobaea populations. Plants were classified as jacobine, erucifoline, mixed or senecionine chemotypes based on presence and absence of the PAs jacobine or erucifoline. Due to the presence of jacobine, total PA concentration in jacobine chemotypes was higher than in erucifoline chemotypes. Both relative and absolute concentrations of individual PAs differed between half-sib and clonal families, which showed that variation in PA patterns had a genetic basis. Within most populations relative abundance of PAs varied considerably between individual plants. Most populations consisted either of the jacobine chemotype or of the erucifoline chemotype, sometimes in combination with mixed or senecionine chemotypes.
Klaas Vrieling - One of the best experts on this subject based on the ideXlab platform.
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Pyrrolizidine Alkaloid variation in shoots and roots of segregating hybrids between jacobaea vulgaris and jacobaea aquatica
New Phytologist, 2011Co-Authors: Klaas Vrieling, Dandan Cheng, Heather Kirk, Patrick P J Mulder, Peter G L KlinkhamerAbstract:Hybridization can lead to novel qualitative or quantitative variation of secondary metabolite (SM) expression that can have ecological and evolutionary consequences. We measured Pyrrolizidine Alkaloid (PA) expression in the shoots and roots of a family including one Jacobaea vulgaris genotype and one Jacobaea aquatica genotype (parental genotypes), two F(1) hybrid genotypes, and 102 F(2) hybrid genotypes using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We detected 37 PAs in the roots and shoots of J. vulgaris, J. aquatica and the hybrids. PA concentrations and compositions differed between genotypes, and between roots and shoots. Three otosenine-like PAs that only occurred in the shoots of parental genotypes were present in the roots of F(2) hybrids; PA compositions were sometimes novel in F(2) hybrids compared with parental genotypes, and in some cases transgressive PA expression occurred. We also found that PAs from within structural groups covaried both in the roots and in the shoots, and that PA expression was correlated between shoots and roots. Considerable and novel variation present among F(2) hybrids indicates that hybridization has a potential role in the evolution of PA diversity in the genus Jacobaea, and this hybrid system is useful for studying the genetic control of PA expression.
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species by environment interactions affect Pyrrolizidine Alkaloid expression in senecio jacobaea senecio aquaticus and their hybrids
Journal of Chemical Ecology, 2010Co-Authors: Heather Kirk, Klaas Vrieling, Eddy Van Der Meijden, Peter G L KlinkhamerAbstract:We examined the effects of water and nutrient availability on the expression of the defense Pyrrolizidine Alkaloids (PAs) in Senecio jacobaea and S. aquaticus. Senecio jacobaea, and S. aquaticus are adapted to different natural habitats, characterized by differing abiotic conditions and different selection pressures from natural enemies. We tested if PA concentration and diversity are plastic over a range of water and nutrient treatments, and also whether such plasticity is dependent on plant species. We also tested the hypothesis that hybridization may contribute to PA diversity within plants, by comparing PA expression in parental species to that in artificially generated F1 hybrids, and also in later generation natural hybrids between S. jacobaea and S. aquaticus. We showed that total PA concentration in roots and shoots is not dependent on species, but that species determines the pattern of PA diversification. Pyrrolizidine Alkaloid diversity and concentration are both dependent on environmental factors. Hybrids produce a putatively novel PA, and this PA is conserved in natural hybrids, that are backcrossed to S. jacobaea. Natural hybrids that are backcrossed several times to S. jacobaea are with regard to PA diversity significantly different from S. jacobaea but not from S. aquaticus, while F1 hybrids are in all cases more similar to S. jacobaea. These results collectively suggest that PA diversity is under the influence of natural selection.
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variation in Pyrrolizidine Alkaloid patterns of senecio jacobaea
Phytochemistry, 2004Co-Authors: Mirka Macel, Klaas Vrieling, Peter G L KlinkhamerAbstract:We studied the variation in Pyrrolizidine Alkaloid (PA) patterns of lab-grown vegetative plants of 11 European Senecio jacobaea populations. Plants were classified as jacobine, erucifoline, mixed or senecionine chemotypes based on presence and absence of the PAs jacobine or erucifoline. Due to the presence of jacobine, total PA concentration in jacobine chemotypes was higher than in erucifoline chemotypes. Both relative and absolute concentrations of individual PAs differed between half-sib and clonal families, which showed that variation in PA patterns had a genetic basis. Within most populations relative abundance of PAs varied considerably between individual plants. Most populations consisted either of the jacobine chemotype or of the erucifoline chemotype, sometimes in combination with mixed or senecionine chemotypes.
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Tritrophic interactions between aphids (Aphis jacobaeae Schrank), ant species, Tyria jacobaeae L., and Senecio jacobaea L. lead to maintenance of genetic variation in Pyrrolizidine Alkaloid concentration
Oecologia, 1991Co-Authors: Klaas Vrieling, Wouter Smit, Ed MeijdenAbstract:We hypothesize that the tritrophic interaction between ants, the aphid Aphis jacobaeae , the moth Tyria jacobaeae , and the plant Senecio jacobaea can explain the genetic variation observed in Pyrrolizidine Alkaloid concentration in natural populations of S. jacobaea . The ant Lasius niger effectively defends S. jacobaea plants infested with A. jacobaeae against larvae of T. jacobaeae . S. jacobaea plants with A. jacobaeae which are defended by ants escape regular defoliation by T. jacobaeae . Plants with aphids and ants have a lower Pyrrolizidine Alkaloid concentration than plants without aphids and ants. When these data are fitted to an existing theoretical model for temporal variation in fitness it is shown that varying herbivore pressure by T. jacobaeae in interaction with ants defending aphid-infested plants with a low Pyrrolizidine Alkaloid concentration can lead to a stable polymorphism in Pyrrolizidine Alkaloid concentration. Costs of the production and maintenance of Pyrrolizidine Alkaloids are not accounted for in the model.
Ming W. Chou - One of the best experts on this subject based on the ideXlab platform.
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high performance liquid chromatography electrospray ionization tandem mass spectrometry for the detection and quantitation of Pyrrolizidine Alkaloid derived dna adducts in vitro and in vivo
Chemical Research in Toxicology, 2010Co-Authors: Ming W. Chou, Frederick A Beland, Qingsu Xia, Yuewei Zhao, Yu-ping Wang, Goncalo Gamboa Da Costa, Mona I Churchwell, Matilde M Marques, Daniel R. DoergeAbstract:Pyrrolizidine Alkaloid-containing plants are widespread in the world and are probably the most common poisonous plants affecting livestock, wildlife, and humans. Pyrrolizidine Alkaloids require metabolism to exert their genotoxicity and tumorigenicity. We have determined that the metabolism of a series of tumorigenic Pyrrolizidine Alkaloids in vitro or in vivo generates a common set of (±)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP)-derived DNA adducts that are responsible for tumor induction. The identification and quantitation of the DHP-derived DNA adducts formed in vivo and in vitro were accomplished previously by 32P-postlabeling/HPLC methodology. In this article, we report the development of a sensitive and specific liquid chromatography−electrospray ionization−tandem mass spectrometry (HPLC-ES-MS/MS) method to detect DHP-derived DNA adducts formed in vitro and in vivo. The method is used to quantify the levels of DHP-2′-deoxyguanosine (dG) and DHP-2′-deoxyadenosine (dA) adducts by mu...
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formation of dhp derived dna adducts from metabolic activation of the prototype heliotridine type Pyrrolizidine Alkaloid heliotrine
Toxicology Letters, 2008Co-Authors: Qingsu Xia, Jian Yan, Ming W. ChouAbstract:Abstract Pyrrolizidine Alkaloid-containing plants are widespread in the world and may be the most common poisonous plants affecting livestock, wildlife, and humans. Pyrrolizidine Alkaloids require metabolism to exert their genotoxicity and tumorigenicity. Our mechanistic studies have determined that metabolism of the retronecine-type (riddelliine, retrorsine, and monocrotaline), heliotridine-type (lasiocarpine), and otonecine-type (clivorine) tumorigenic Pyrrolizidine Alkaloids in vivo and/or in vitro all generates a common set of 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP)-derived DNA adducts responsible for tumor induction. All the Pyrrolizidine Alkaloids studied previously are diesters with an ester linkage at the C7 and C9 positions of the necine base. In this study, we report that F344 rat liver microsomal metabolism of heliotrine, a tumorigenic monoester bearing a hydroxyl group at the C7 of the necine base, resulted in the formation of the dehydroheliotridine (DHH) metabolite. When incubations of heliotrine were carried out in the presence of calf thymus DNA, the same set of DHP-derived DNA adducts was formed. These results support that DHP-derived DNA adducts are potential common biomarkers of Pyrrolizidine Alkaloid exposure and tumorigenicity. For comparison, the dehydroretronecine (DHR)-derived DNA adducts formed from metabolism of riddleiine, retrorsine, monocrotaline, riddelleiine N-oxide, and retrorsine N-oxide were measured in parallel; the levels of DHP-derived DNA adduct formation were in the order: riddelliine ≈ retrorsine > monocrotaline > retrorsine N-oxide ≥ riddelliine N-oxide > heliotrine.
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metabolic activation of the tumorigenic Pyrrolizidine Alkaloid monocrotaline leading to dna adduct formation in vivo
Cancer Letters, 2005Co-Authors: Yu-ping Wang, Jian Yan, Richard D Beger, Ming W. ChouAbstract:Pyrrolizidine Alkaloids are naturally occurring genotoxic chemicals produced by a large number of plants. The high toxicity of many Pyrrolizidine Alkaloids has caused considerable loss of free-ranging livestock due to liver and pulmonary lesions. Chronic exposure of toxic Pyrrolizidine Alkaloids to laboratory animals induces cancer. This investigation studies the metabolic activation of retrorsine, a representative naturally occurring tumorigenic Pyrrolizidine Alkaloid, and shows that a genotoxic mechanism is correlated to the tumorigenicity of retrorsine. Metabolism of retrorsine by liver microsomes of F344 female rats produced two metabolites, 6, 7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP), at a rate of 4.8 ± 0.1 nmol/mg/min, and retrorsine-N-oxide, at a rate of 17.6±0.5 nmol/mg/min. Metabolism was enhanced 1.7-fold by using liver microsomes prepared from dexamethasone-treated rats. DHP formation was inhibited 77% and retrorsine N-oxide formation was inhibited 29% by troleandomycin, a P450 3A enzyme inhibitor. Metabolism of retrorsine with lung, kidney, and spleen microsomes from dexamethasone-treated rats also generated DHP and the N-oxide derivative. When rat liver microsomal metabolism of retrorsine occurred in the presence of calf thymus DNA, a set of DHP-derived DNA adducts was formed; these adducts were detected and quantified by using a previously developed 32 P-postlabeling/HPLC method. These same DNA adducts were also found in liver DNA of rats gavaged with retrorsine. Since DHP-derived DNA adducts are suggested to be potential biomarkers of riddelliine- induced tumorigenicity, our results indicate that (i) similar to the metabolic activation of riddelliine, the mechanism of retrorsine-induced carcinogenicity in rats is also through a genotoxic mechanism involving DHP; and (ii) the set of DHP-derived DNA adducts found in liver DNA of rats gavaged with retrorsine or riddelliine can serve as biomarkers for the tumorigenicity induced by retronecine-type Pyrrolizidine Alkaloids.
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metabolic activation of the tumorigenic Pyrrolizidine Alkaloid retrorsine leading to dna adduct formation in vivo
International Journal of Environmental Research and Public Health, 2005Co-Authors: Yu-ping Wang, Ming W. ChouAbstract:Pyrrolizidine Alkaloids are naturally occurring genotoxic chemicals produced by a large number of plants. The high toxicity of many Pyrrolizidine Alkaloids has caused considerable loss of free-ranging livestock due to liver and pulmonary lesions. Chronic exposure of toxic Pyrrolizidine Alkaloids to laboratory animals induces cancer. This investigation studies the metabolic activation of retrorsine, a representative naturally occurring tumorigenic Pyrrolizidine Alkaloid, and shows that a genotoxic mechanism is correlated to the tumorigenicity of retrorsine. Metabolism of retrorsine by liver microsomes of F344 female rats produced two metabolites, 6, 7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP), at a rate of 4.8 ± 0.1 nmol/mg/min, and retrorsine-N-oxide, at a rate of 17.6±0.5 nmol/mg/min. Metabolism was enhanced 1.7-fold by using liver microsomes prepared from dexamethasone-treated rats. DHP formation was inhibited 77% and retrorsine N-oxide formation was inhibited 29% by troleandomycin, a P450 3A enzyme inhibitor. Metabolism of retrorsine with lung, kidney, and spleen microsomes from dexamethasone-treated rats also generated DHP and the N-oxide derivative. When rat liver microsomal metabolism of retrorsine occurred in the presence of calf thymus DNA, a set of DHP-derived DNA adducts was formed; these adducts were detected and quantified by using a previously developed 32P-postlabeling/HPLC method. These same DNA adducts were also found in liver DNA of rats gavaged with retrorsine. Since DHP-derived DNA adducts are suggested to be potential biomarkers of riddelliine-induced tumorigenicity, our results indicate that (i) similar to the metabolic activation of riddelliine, the mechanism of retrorsine-induced carcinogenicity in rats is also through a genotoxic mechanism involving DHP; and (ii) the set of DHP-derived DNA adducts found in liver DNA of rats gavaged with retrorsine or riddelliine can serve as biomarkers for the tumorigenicity induced by retronecine-type Pyrrolizidine Alkaloids.
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Human liver microsomal reduction of Pyrrolizidine Alkaloid N-oxides to form the corresponding carcinogenic parent Alkaloid.
Toxicology Letters, 2005Co-Authors: Yu-ping Wang, Jian Yan, Ming W. ChouAbstract:Abstract Retronecine-based Pyrrolizidine Alkaloids, such as riddelliine, retrorsine, and monocrotaline, are toxic to domestic livestock and carcinogenic to laboratory rodents. Previous in vitro metabolism studies showed that (±)6,7-dihydro-7-hydroxy-1-(hydroxymethyl)-5H-pyrrolizine (DHP) and Pyrrolizidine Alkaloid N-oxides were the major metabolites of these compounds. DHP is the reactive metabolite of Pyrrolizidine Alkaloids and Pyrrolizidine Alkaloid N-oxides are generally regarded as detoxification products. However, a previous study of rat liver microsomal metabolism of riddelliine N-oxide demonstrated that DHP and its parent compound, riddelliine, were generated as the major metabolites of riddelliine N-oxide. In this study the metabolic activation of the three retronecine-based Pyrrolizidine Alkaloid N-oxides by human liver microsomes is investigated under oxidative and hypoxic conditions. Results shows that both the DHP and the corresponding parent Pyrrolizidine Alkaloids are the major metabolites of the human liver microsomal metabolism of Pyrrolizidine Alkaloid N-oxides. Under oxidative conditions, reduction of the N-oxide to Pyrrolizidine Alkaloid is inhibited and while under hypoxic conditions, DHP formation is dramatically decreased. The oxidative and reductive products generated from the metabolism of Pyrrolizidine Alkaloid N-oxides are substrate-, enzyme- and time-dependent. In the presence of troleandomycin, a microsomal CYP3A inhibitor, DHP formation is inhibited by more than 70%, while the N-oxide reduction was not affected. The level of microsomal enzyme activity in human liver is comparable with rats. The rate of in vitro metabolism by either human and rat liver microsomes follows the order of riddelliine ≥ retrorsine > monocrotaline, and DHP-derived DNA adducts are detected and quantified by 32P-postlabeling/HPLC analysis. Similar DHP-derived DNA adducts are found in liver DNA of F344 rats gavaged with the Pyrrolizidine Alkaloid N-oxides (1.0 mg/kg). The levels of in vivo DHP-DNA adduct formation is correlated with the level of in vitro DHP formation. Our results indicate that Pyrrolizidine Alkaloid N-oxides may be hepatocarcinogenic to rats through a genotoxic mechanism via the conversion of the N-oxides to their corresponding parent Pyrrolizidine Alkaloids, and these results may be relevant to humans.
Ge Lin - One of the best experts on this subject based on the ideXlab platform.
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tu san qi gynura japonica the culprit behind Pyrrolizidine Alkaloid induced liver injury in china
Acta Pharmacologica Sinica, 2020Co-Authors: Lin Zhu, Hong Gao, Chunyuan Zhang, Hubiao Chen, Jiyao Wang, Ge LinAbstract:Herbs and dietary supplement-induced liver injury (HILI) is the leading cause of drug-induced liver injury in China. Among different hepatotoxic herbs, the Pyrrolizidine Alkaloid (PA)-producing herb Gynura japonica contributes significantly to HILI by inducing hepatic sinusoidal obstruction syndrome (HSOS), a liver disorder characterized by hepatomegaly, hyperbilirubinemia, and ascites. In China, G. japonica has been used as one of the plant species for Tu-San-Qi and is often misused with non-PA-producing Tu-San-Qi (Sedum aizoon) or even San-Qi (Panax notoginseng) for self-medication. It has been reported that over 50% of HSOS cases are caused by the intake of PA-producing G. japonica. In this review, we provide comprehensive information to distinguish these Tu-San-Qi-related herbal plant species in terms of plant/medicinal part morphologies, medicinal indications, and chemical profiles. Approximately 2156 Tu-San-Qi-associated HSOS cases reported in China from 1980 to 2019 are systematically reviewed in terms of their clinical manifestation, diagnostic workups, therapeutic interventions, and outcomes. In addition, based on the application of our developed mechanism-based biomarker of PA exposure, our clinical findings on the definitive diagnosis of 58 PA-producing Tu-San-Qi-induced HSOS patients are also elaborated. Therefore, this review article provides the first comprehensive report on 2214 PA-producing Tu-San-Qi (G. japonica)-induced HSOS cases in China, and the information presented will improve public awareness of the significant incidence of PA-producing Tu-San-Qi (G. japonica)-induced HSOS and facilitate future prevention and better clinical management of this severe HILI.
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Toxicoproteomic assessment of liver responses to acute Pyrrolizidine Alkaloid intoxication in rats
Journal of Environmental Science and Health Part C, 2018Co-Authors: William Chi-shing Tai, Imran Khan, Wing-yan Wong, Wood Yee Chan, W.l. Wendy Hsiao, Ge LinAbstract:A toxicoproteomic study was performed on liver of rats treated with retrorsine (RTS), a representative hepatotoxic Pyrrolizidine Alkaloid at a toxic dose (140 mg/kg) known to cause severe acute hepatotoxicity. By comparing current data with our previous findings in mild liver lesions of rats treated with a lower dose of RTS, seven proteins and three toxicity pathways of vascular endothelial cell death, which was further verified by observed sinusoidal endothelial cell losses, were found uniquely associated with retrorsine-induced hepatotoxicity. This toxicoproteomic study of acute Pyrrolizidine Alkaloid intoxication lays a foundation for future investigation to delineate molecular mechanisms of Pyrrolizidine Alkaloid-induced hepatotoxicity.
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Pyrrolizidine Alkaloid derived dna adducts are common toxicological biomarkers of Pyrrolizidine Alkaloid n oxides
Journal of Food and Drug Analysis, 2017Co-Authors: Qingsu Xia, Kellie A Woodling, Ge LinAbstract:There are 660 Pyrrolizidine Alkaloids (PAs) and PA N-oxides present in the plants, with approximately half being possible carcinogens. We previously reported that a set of four PA-derived DNA adducts is formed in the liver of rats administered a series of hepatocarcinogenic PAs and a PA N-oxide. Based on our findings, we hypothesized that this set of DNA adducts is a common biological biomarker of PA-induced liver tumor formation. In this study, we determined that rat liver microsomal metabolism of five hepatocarcinogenic PAs (lasiocarpine, retrorsine, riddelliine, monocrotaline, and heliotrine) and their corresponding PA N-oxides produced the same set of DNA adducts. Among these compounds, lasiocarpine N-oxide, retrorsine N-oxide, monocrotaline N-oxide, and heliotrine N-oxide are for first time shown to be able to produce these DNA adducts. These results further support the role of these DNA adducts as potential common biomarkers of PA-induced liver tumor initiation.
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the long persistence of Pyrrolizidine Alkaloid derived dna adducts in vivo kinetic study following single and multiple exposures in male icr mice
Archives of Toxicology, 2017Co-Authors: Qingsu Xia, Ge Lin, Lin Zhu, Junyi XueAbstract:Pyrrolizidine Alkaloid (PA)-containing plants are widespread in the world and the most common poisonous plants affecting livestock, wildlife, and humans. Our previous studies demonstrated that PA-derived DNA adducts can potentially be a common biological biomarker of PA-induced liver tumor formation. In order to validate the use of these PA-derived DNA adducts as a biomarker, it is necessary to understand the basic kinetics of the PA-derived DNA adducts formed in vivo. In this study, we studied the dose-dependent response and kinetics of PA-derived DNA adduct formation and removal in male ICR mice orally administered with a single dose (40 mg/kg) or multiple doses (10 mg/kg/day) of retrorsine, a representative carcinogenic PA. In the single-dose exposure, the PA-derived DNA adducts exhibited dose-dependent linearity and persisted for up to 4 weeks. The removal of the adducts following a single-dose exposure to retrorsine was biphasic with half-lives of 9 h (t 1/2α) and 301 h (~12.5 days, t 1/2β). In the 8-week multiple exposure study, a marked accumulation of PA-derived DNA adducts without attaining a steady state was observed. The removal of adducts after the multiple exposure also demonstrated a biphasic pattern but with much extended half-lives of 176 h (~7.33 days, t 1/2α) and 1736 h (~72.3 days, t 1/2β). The lifetime of PA-derived DNA adducts was more than 8 weeks following the multiple-dose treatment. The significant persistence of PA-derived DNA adducts in vivo supports their role in serving as a biomarker of PA exposure.
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Pyrrolizidine Alkaloid protein adducts potential non invasive biomarkers of Pyrrolizidine Alkaloid induced liver toxicity and exposure
Chemical Research in Toxicology, 2016Co-Authors: Qingsu Xia, Frederick A Beland, Yuewei Zhao, Ge Lin, Lining CaiAbstract:Pyrrolizidine Alkaloids (PAs) are phytochemicals present in hundreds of plant species from different families widely distributed in many geographical regions around the world. PA-containing plants are probably the most common type of poisonous plants affecting livestock, wildlife, and humans. There have been many large-scale human poisonings caused by the consumption of food contaminated with toxic PAs. PAs require metabolic activation to generate pyrrolic metabolites to exert their toxicity. In this study, we developed a novel method to quantify pyrrole-protein adducts present in the blood. This method involves the use of AgNO3 in acidic ethanol to cleave the thiol linkage of pyrrole-protein (DHP-protein) adducts, and the resulting 7,9-di-C2H5O–DHP is quantified by HPLC-ES-MS/MS multiple reaction monitoring analysis in the presence of a known quantity of isotopically labeled 7,9-di-C2D5O–DHP internal standard. Using this method, we determined that diester-type PAs administered to rats produced higher lev...
