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Thoden TC, Boppré M, Hallmann J. Effects of pyrrolizidine alkaloids on the performance of plant-parasitic and free-living nematodes. PEST MANAGEMENT SCIENCE 2009; 65:823-30. [PMID: 19378265 DOI: 10.1002/ps.1764] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
BACKGROUND Chemical nematicides such as methyl bromide have for decades played a significant role in the management of plant-parasitic nematodes. Their application is problematic because of negative environmental impacts, and therefore methyl bromide was phased out in Europe in 2005. A possible alternative to synthetically derived nematicides is seen in the use of plants and/or their secondary metabolites. These plants could either be used as nematicidal green manure or as a source for nematicidal extracts. This study aimed to evaluate the effects of 1,2-dehydropyrrolizidine alkaloids (PAs), a group of secondary plant metabolites found in hundreds of plant species throughout the world, on the performance of plant-parasitic and free-living nematodes. RESULTS PAs induced nematicidal, ovicidal and repellent effects on different plant-parasitic and free-living nematodes. There was no conclusive ranking in toxicity for the different structural types of PAs tested. However, the effects were often more pronounced for the tertiary than for the oxidised form of PAs. Further, large differences were observed in the susceptibility of different nematode species to PAs. CONCLUSIONS PAs do affect several performance parameters and developmental stages of nematodes. Therefore, PA-producing plants such as species of Crotalaria, Ageratum or Senecio might be promising candidates for nematode management strategies. [Correction made here after initial online publication].
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Affiliation(s)
- Tim C Thoden
- Forstzoologisches Institut, Albert-Ludwigs-Universität, D-79085 Freiburg i.Br., Germany.
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2
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Chung WG, Buhler DR. Differential metabolism of the pyrrolizidine alkaloid, senecionine, in fischer 344 and sprague-dawley Rats. Arch Pharm Res 2004; 27:547-53. [PMID: 15202562 DOI: 10.1007/bf02980130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The pyrrolizidine alkaloids (PAs), contained in a number of traditional remedies in Africa and Asia, show wide variations in metabolism between animal species but little work has been done to investigate differences between animal strains. The metabolism of the PA senecionine (SN) in Fischer 344 (F344) rats has been studied in order to compare to that found in the previously investigated Sprague-Dawley (SD) rats (Drug Metab. Dispos. 17: 387, 1989). There was no difference in the formation of (+/-) 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP, bioactivation) by hepatic microsomes from either sex of SD and F344 rats. However, hepatic microsomes from male and female F344 rats had greater activity in the N-oxidation (detoxication) of SN by 88% and 180%, respectively, when compared to that of male and female SD rats. Experiments conducted at various pH showed an optimum pH of 8.5, the optimal pH for flavin-containing monooxygenase (FMO), for SN N-oxidation by hepatic microsomes from F344 females. In F344 males, however, a bimodal pattern was obtained with activity peaks at pH 7.6 and 8.5 reflecting the possible involvement of both cytochrome P450 (CYP) and FMO. Use of specific inhibitors (SKF525A, 1-benzylimidazole and methimazole) showed that the N-oxide of SN was primarily produced by FMO in both sexes of F344 rats. In contrast, SN N-oxide formation is known to be catalyzed mainly by CYP2C11 rather than FMO in SD rats. This study, therefore, demonstrated that there were substantial differences in the formation of SN N-oxide by hepatic microsomes from F344 and SD rats and that this detoxification is catalyzed primarily by two different enzymes in the two rat strains. These findings suggest that significant variations in PA biotransformation can exist between different animal strains.
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Affiliation(s)
- Woon-Gye Chung
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA
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3
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Fu PP, Xia Q, Lin G, Chou MW. Pyrrolizidine Alkaloids—Genotoxicity, Metabolism Enzymes, Metabolic Activation, and Mechanisms. Drug Metab Rev 2004; 36:1-55. [PMID: 15072438 DOI: 10.1081/dmr-120028426] [Citation(s) in RCA: 364] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Pyrrolizidine alkaloid-containing plants are widely distributed in the world and are probably the most common poisonous plants affecting livestock, wildlife, and humans. Because of their abundance and potent toxicities, the mechanisms by which pyrrolizidine alkaloids induce genotoxicities, particularly carcinogenicity, were extensively studied for several decades but not exclusively elucidated until recently. To date, the pyrrolizidine alkaloid-induced genotoxicities were revealed to be elicited by the hepatic metabolism of these naturally occurring toxins. In this review, we present updated information on the metabolism, metabolizing enzymes, and the mechanisms by which pyrrolizidine alkaloids exert genotoxicity and tumorigenicity.
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Affiliation(s)
- Peter P Fu
- National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
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4
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Huan JY, Miranda CL, Buhler DR, Cheeke PR. Species differences in the hepatic microsomal enzyme metabolism of the pyrrolizidine alkaloids. Toxicol Lett 1998; 99:127-37. [PMID: 9817084 DOI: 10.1016/s0378-4274(98)00152-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Species differences in pyrrolic metabolites and senecionine (SN) N-oxide formation among eight animal species (sheep, cattle, gerbils, rabbits, hamsters, Japanese quail, chickens, rats) varying in susceptibility to pyrrolizidine alkaloid (PA) intoxication were measured in vitro by hepatic microsomal incubations. The results suggested that there is not a strong correlation between the production of pyrrolic metabolites and susceptibility of animals to PA toxicity. The rate of PA activation in hamsters, a resistant species, measured by formation of (+/-)6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) far exceeded the rate of SN N-oxide formation (detoxification) (DHP/N-oxide = 2.29). In contrast, SN N-oxide was the major metabolite in sheep, another resistant species, with much lower production of DHP (DHP/N-oxide = 0.26). The roles of cytochrome P450s and flavin-containing monooxygenases (FMO) in bioactivation and detoxification of pyrrolizidine alkaloids (PA) were studied in vitro using sheep and hamster hepatic microsomes. Chemical and immunochemical inhibition data suggested that the conversion of SN to DHP is catalyzed mainly by cytochrome P450s (68-82%), whereas the formation of SN N-oxide is carried out largely by FMO (55-71%). There also appeared to be a high rate of glutathione-DHP conjugation in hamster (63%) and sheep (79%) liver microsomal incubation mixtures. Therefore, low rates of pyrrole metabolite production coupled with glutathione conjugation in sheep may explain the resistance of sheep to SN, whereas the high rate of GSH-DHP conjugation may be one of the factors contributing to the resistance of hamsters to intoxication by this PA.
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Affiliation(s)
- J Y Huan
- Toxicology Program, Oregon State University, Corvallis 97311, USA
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5
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Schultze AE, Roth RA. Chronic pulmonary hypertension--the monocrotaline model and involvement of the hemostatic system. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 1998; 1:271-346. [PMID: 9776954 DOI: 10.1080/10937409809524557] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Monocrotaline (MCT) is a toxic pyrrolizidine alkaloid of plant origin. Administration of small doses of MCT or its active metabolite, monocrotaline pyrrole (MCTP), to rats causes delayed and progressive lung injury characterized by pulmonary vascular remodeling, pulmonary hypertension, and compensatory right heart hypertrophy. The lesions induced by MCT(P) administration in rats are similar to those observed in certain chronic pulmonary vascular diseases of people. This review begins with a synopsis of the hemostatic system, emphasizing the role of endothelium since endothelial cell dysfunction likely underlies the pathogenesis of MCT(P)-induced pneumotoxicity. MCT toxicology is discussed, focusing on morphologic, pulmonary mechanical, hemodynamic, and biochemical and molecular alterations that occur after toxicant exposure. Fibrin and platelet thrombosis of the pulmonary microvasculature occurs after administration of MCT(P) to rats, and several investigators have hypothesized that thrombi contribute to the lung injury and pulmonary hypertension. The evidence for involvement of the various components of the hemostatic system in MCT(P)-induced vascular injury and remodeling is reviewed. Current evidence is consistent with involvement of platelets and an altered fibrinolytic system, yet much remains to be learned about specific events and signals in the vascular pathogenesis.
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MESH Headings
- Animals
- Disease Models, Animal
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/pathology
- Hemostasis/drug effects
- Humans
- Hypertension, Pulmonary/blood
- Hypertension, Pulmonary/chemically induced
- Hypertension, Pulmonary/etiology
- Hypertrophy, Right Ventricular/blood
- Hypertrophy, Right Ventricular/chemically induced
- Hypertrophy, Right Ventricular/etiology
- Monocrotaline/adverse effects
- Monocrotaline/analogs & derivatives
- Monocrotaline/toxicity
- Plants, Medicinal/adverse effects
- Plants, Toxic/adverse effects
- Rats
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Affiliation(s)
- A E Schultze
- Department of Pathology, College of Veterinary Medicine, University of Tennessee, Knoxville, USA
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6
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Huan JY, Miranda CL, Buhler DR, Cheeke PR. The roles of CYP3A and CYP2B isoforms in hepatic bioactivation and detoxification of the pyrrolizidine alkaloid senecionine in sheep and hamsters. Toxicol Appl Pharmacol 1998; 151:229-35. [PMID: 9707499 DOI: 10.1006/taap.1998.8482] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The roles of cytochrome CYP3A and CYP2B isozymes in the bioactivation and detoxification of the pyrrolizidine alkaloid (PA) senecionine (SN) have been investigated in vitro with sheep and hamster hepatic microsomes. Our results show that the rate of SN activation measured by (+/-)-6, 7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) formation greatly exceeded the rate of SN N-oxide formation (detoxification) in hamsters. In contrast, SN N-oxide, a detoxification product, was the major metabolite in sheep with much lower DHP production. Immunoinhibition studies with anti-sheep CYP3A and CYP2B antibodies show that members of CYP3A subfamily play the major role in the conversion of PA to pyrrolic metabolites in both species (over 90% in sheep; 68% in hamster). These enzymes also contribute 38.8 and 41. 3% of SN N-oxidation in sheep and hamsters, respectively. In contrast, CYP2B isoforms have a limited capacity toward DHP formation in both species (47% in sheep; 32% in hamster), while these enzymes catalyzed only 24.6 and 35.4% SN N-oxidation in sheep and hamster, respectively. Using triacetyloleandomycin (TAO) and gestodene, two highly selective chemical inhibitors of CYP3A isoforms, our data show that 90% of DHP formation was inhibited by either inhibitor in sheep. Gestodene appeared to be more efficient than TAO in the inhibition of DHP production in hamsters. Testosterone 6beta-hydroxylase activity, a functional marker of CYP3A, was significantly inhibited by TAO and gestodene in sheep liver microsomes and by gestodene (100 microM) in hamster liver microsomes. These results suggest that CYP3A isozymes have important roles in bioactivation and detoxification of PA in both species, whereas CYP2B subfamily members are less efficient in biotransformation of PA.
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Affiliation(s)
- J Y Huan
- Toxicology Program, Oregon State University, Corvallis, Oregon 97331, USA
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7
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Reid MJ, Lamé MW, Morin D, Wilson DW, Segall HJ. Monocrotaline metabolism and distribution in Fisher 344 and Sprague-Dawley rats. Comp Biochem Physiol B Biochem Mol Biol 1997; 117:115-23. [PMID: 9180020 DOI: 10.1016/s0305-0491(96)00323-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The metabolism and distribution of 14C-monocrotaline in Fisher 344 (F344) rats was compared with that in Sprague-Dawley (SD) rats. In vitro microsomal preparations, in situ isolated perfused livers and in vivo excretion and distribution studies were used to discern any differences between these two strains. These strains have previously been shown to differ in their susceptibility to monocrotaline-induced pulmonary hypertension. Hepatic phase I metabolism appears to be similar in both strains with N-oxidation and dehydrogenation to the reactive pyrroles as the major pathways. During the liver perfusions, SD rats generated more monocrotalic acid than F344 rats, but the microsome and excretion studies demonstrated no significant differences in the amount of monocrotalic acid. Monocrotalic acid is a stable byproducer of dehydromonocrotaline reacting with cellular nucleophiles and indicates the amount of monocrotaline dehydrogenation when carboxylesterase activity is negligible. These data suggest that the differences in strain susceptibility to pulmonary vascular toxicity is most likely due to differences in their response to the toxic metabolites.
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Affiliation(s)
- M J Reid
- Department of Veterinary Medicine and Molecular Biosciences, University of California, Davis 95616, USA
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8
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Chung WG, Miranda CL, Buhler DR. A cytochrome P4502B form is the major bioactivation enzyme for the pyrrolizidine alkaloid senecionine in guinea pig. Xenobiotica 1995; 25:929-39. [PMID: 8553686 DOI: 10.3109/00498259509046664] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
1. We have purified three P450s from the liver of the phenobarbital (PB)-treated guinea pig in order to evaluate the role of these enzymes in pyrrolizidine alkaloid (PA) metabolism. 2. PB treatment of guinea pig increased the hepatic microsomal conversion of the PA senecionine (SN) to the pyrrolic metabolite (+/-)6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP), an activation product, and SN N-oxide, a detoxification product by 224 and 70% respectively. 3. Reconstitution of a PB-inducible guinea pig P4502B isoform (M(r) = 57,512 by MALDI-TOF mass spectrometry) in a reconstituted system metabolized SN to DHP and SN N-oxide at rates of 1.98 and 1.45 min-1 respectively. A second purified guinea pig P450, a 2C-type isoform (M(r) = 56,496 by MALDI-TOF mass spectrometry), produced SN N-oxide from SN at the rate of 13.3 min-1 but catalyzed little DHP formation. The third guinea pig P450, an apparent 3A type (M(r) = 54-56,000 by SDS-PAGE), lost its catalytic activity towards SN during the final purification process. 4. Immunoinhibition of microsomal SN metabolism by rabbit antibodies raised against the guinea pig P4502B, 2C and 3A isoforms indicated that the 2B played the most important role (> 70% of the total metabolism) in bioactivation of SN in both the untreated or PB-treated guinea pig, whereas 2C and 3A seemed to exhibit little (around 13%) PA metabolism. P4502B, along with flavin-containing monooxygenase, also contributed to the detoxification of SN in both the untreated (34%) and PB-treated (40%) guinea pig. 5. This study suggests that the putative P4502B form plays the most important role in SN bioactivation in guinea pig.
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Affiliation(s)
- W G Chung
- Department of Agricultural Chemistry, Oregon State University, Corvallis 97331, USA
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9
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Dueker SR, Lamé MW, Segall HJ. Hydrolysis of pyrrolizidine alkaloids by guinea pig hepatic carboxylesterases. Toxicol Appl Pharmacol 1992; 117:116-21. [PMID: 1440605 DOI: 10.1016/0041-008x(92)90225-h] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Two carboxylesterases (GPL1 and GPH1) were isolated from guinea pig hepatic microsomes and assayed for activity using the following pyrrolizidine alkaloids (PAs): seneciphylline (SNP), monocrotaline (MCT), and a mixture of senecionine (SEN) and integerrimine (INT) referred to as SEN-INT. GPH1 was able to effect the hydrolysis of all PAs, however, only minimal activity was seen for SEN-INT. The specific activity of GPL1 for p-nitrophenyl acetate was four times that of GPH1, but the former showed no activity toward PAs. The molecular weights and pIs were determined for both enzymes, and the Michaelis-Menten constants for two PAs, SNP and MCT were obtained using GPH1. The response to inhibitors confirmed GPH1 as a type B serine hydrolase although it was also inhibited by HgCl2. The isolation of a PA active esterase from the guinea pig may help to explain the resistance of this animal to PA intoxication, while enzyme substrate specificity may explain how the guinea pig's susceptibility to PA intoxication can differ toward various PAs.
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Affiliation(s)
- S R Dueker
- Department of Veterinary Pharmacology and Toxicology, University of California, Davis 95616
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10
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Miranda CL, Chung W, Reed RE, Zhao X, Henderson MC, Wang JL, Williams DE, Buhler DR. Flavin-containing monooxygenase: a major detoxifying enzyme for the pyrrolizidine alkaloid senecionine in guinea pig tissues. Biochem Biophys Res Commun 1991; 178:546-52. [PMID: 1907134 DOI: 10.1016/0006-291x(91)90142-t] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Evidence based on optimal pH, thermal stability, and enzyme inhibition data suggests that the NADPH-dependent microsomal N-oxidation of the pyrrolizidine alkaloid senecionine is carried out largely by flavin-containing monooxygenase in guinea pig liver, lung, and kidney. In contrast, the hepatic microsomal conversion of senecionine to the pyrrole metabolite (+/-)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) is catalyzed largely by cytochrome P450. However, the rate of senecionine N-oxide formation (detoxication) far exceeded the rate of DHP formation (activation) in guinea pig liver microsomes over a range of pHs (pH 6.8 to 9.8). In guinea pig lung and kidney microsomes, N-oxide was the major metabolite formed from senecionine with little or no production of DHP. The high rate of detoxication coupled with the low level of activation of senecionine in liver, lung, and kidney may help explain the apparent resistance of the guinea pig to intoxication by senecionine and other pyrrolizidine alkaloids.
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Affiliation(s)
- C L Miranda
- Department of Agricultural Chemistry, Oregon State University, Corvallis 97331
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11
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Chu PS, Segall HJ. Species difference in the urinary excretion of isatinecic acid from the pyrrolizidine alkaloid retrorsine. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C, COMPARATIVE PHARMACOLOGY AND TOXICOLOGY 1991; 100:683-6. [PMID: 1687569 DOI: 10.1016/0742-8413(91)90061-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. The urinary excretion of the metabolites, isatinecic acid and pyrrolic metabolites from the pyrrolizidine alkaloid retrosine were lower in the resistant species, guinea-pigs, than the susceptible species, mice, hamsters and rats. 2. The urinary N-oxides levels, however, were higher in guinea-pigs relative to mice, hamsters and rats. 3. These results conform to the postulate that a common metabolic pathway exists between the formation of isatinecic acid and pyrrolic metabolites. 4. The resistance of guinea-pigs to PA poisoning is attributed to the high metabolism of PAs to N-oxides combined with a corresponding low conversion to pyrrolic metabolites.
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Affiliation(s)
- P S Chu
- Department of Veterinary Pharmacology and Toxicology, University of California, Davis 95616
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12
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Winter CK, Segall HJ, Jones AD. Determination of pyrrolizidine alkaloid metabolites from mouse liver microsomes using tandem mass spectrometry and gas chromatography/mass spectrometry. BIOMEDICAL & ENVIRONMENTAL MASS SPECTROMETRY 1988; 15:265-73. [PMID: 3365497 DOI: 10.1002/bms.1200150506] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The rapid and sensitive identification and quantification of important pyrrolizidine alkaloid metabolites using tandem mass spectrometry (MS/MS) and gas chromatography/mass spectrometry (GC/MS) is described. Identifications of N-oxide and hydrolytic metabolites of the pyrrolizidine alkaloids senecionine and monocrotaline in extracts of mouse hepatic microsomal incubations were accomplished by comparing collisionally activated decomposition/mass-analyzed ion kinetic energy spectra of specific ions from microsomal extracts with spectra obtained from synthetic standards of suspected metabolites. Trace amounts of the toxic metabolite dihydropyrrolizine (DHP) were observed by GC/MS of trimethylsilyl (TMS) derivatives, but the amounts present in hepatic microsomal extracts were below the MS/MS limit of detection. Quantitative determinations of senecionine N-oxide were performed by fast atom bombardment MS/MS. Suppression of N-oxide ionization by other substances in the extracts was judged to be minimal. The TMS derivatives of the metabolites senecic acid, monocrotalic acid and DHP were quantified using capillary GC/MS. Results from the study demonstrate that the relative contributions of the three major pathways of pyrrolizidine alkaloid metabolism (N-oxidation, hydrolysis and oxidation to pyrrolic compounds) can be assessed using a single analytical instrument and minimal sample preparation.
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Affiliation(s)
- C K Winter
- Department of Veterinary Pharmacology and Toxicology, University of California, Davis 95616
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13
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Winter CK, Segall HJ, Jones AD. Species differences in the hepatic microsomal metabolism of the pyrrolizidine alkaloid senecionine. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C, COMPARATIVE PHARMACOLOGY AND TOXICOLOGY 1988; 90:429-33. [PMID: 2903002 DOI: 10.1016/0742-8413(88)90022-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
1. The comparative metabolism of the pyrrolizidine alkaloid (PA) senecionine was studied in vitro in incubations of rat, guinea pig, cow, horse, and sheep hepatic microsomes. 2. Levels of the toxic pyrrolic metabolite 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) were higher from guinea pig incubations (39.9 nmol/mg protein) than from other species (range 0.07 to 7.5 nmol/mg); results disagree with prior studies which used nonspecific techniques and suggest that the guinea pig's resistance to certain PAs may be due to resistance to pyrrole toxicity rather than low pyrrole formation. 3. Minor differences in senecionine N-oxidation and hydrolysis existed between the various species.
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Affiliation(s)
- C K Winter
- Department of Veterinary Pharmacology and Toxicology, University of Calfornia, Davis 95616
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Bruner LH, Carpenter LJ, Hamlow P, Roth RA. Effect of a mixed function oxidase inducer and inhibitor on monocrotaline pyrrole pneumotoxicity. Toxicol Appl Pharmacol 1986; 85:416-27. [PMID: 3094196 DOI: 10.1016/0041-008x(86)90349-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Monocrotaline (MCT) produces vascular injury to the lung, pulmonary hypertension, and right ventricular hypertrophy when injected into rats. It is well established that the pneumotoxicity of MCT depends on its hepatic bioactivation to monocrotaline pyrrole (MCTP) and perhaps other toxic metabolites. To test whether MCTP requires further bioactivation, we synthesized this metabolite chemically, confirmed its structure using fast-atom bombardment-mass spectrometry and nuclear magnetic resonance, and injected it into rats previously treated with an inducer or inhibitor of MFOs. Pretreatment with either phenobarbital or SKF-525A did not alter the pneumotoxic effects of an intravenous injection of MCTP. Rats given the same intravenous dose of either MCT, MCT N-oxide, or MCTP responded with toxicity only to MCTP. MCTP added to rat serum in vitro resulted in a color change (Amax = 477 nm) that developed over several seconds, an observation consistent with degradation of MCTP in serum. To explore the possibility that aqueous degradation products might contribute to its toxicity, the same intravenous dose of MCTP was administered to rats in N,N-dimethylformamide (DMF), serum, or saline. Only MCTP administered in in DMF resulted in toxicity. These results support the contention that MCT requires metabolism to MCTP to produce pneumotoxicity and that exposure to aqueous media renders MCTP incapable of causing lung injury.
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Cheeke PR, Pierson-Goeger ML. Toxicity of Senecio jacobaea and pyrrolizidine alkaloids in various laboratory animals and avian species. Toxicol Lett 1983; 18:343-9. [PMID: 6665808 DOI: 10.1016/0378-4274(83)90116-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The chronic toxicity of tansy ragwort (Senecio jacobaea) to several herbivorous laboratory animals and to chicks and turkey poults was examined by feeding the dried plant as a component of a mixed diet. Gerbils, hamsters and guinea pigs were resistant to chronic toxicity. Gerbils were highly resistant, consuming over 3500% of their body weight of the dried plant, whereas susceptible species succumb to a tansy ragwort intake of 5-20% of their body weight. Guinea pigs and gerbils were resistant to acute toxicity of injected monocrotaline, a pyrrolizidine alkaloid (PA). They were moderately resistant to acute toxicity of injected tansy ragwort alkaloids. Both chicks and turkey poults were susceptible to chronic toxicity of dietary tansy ragwort.
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Hendricks JD, Sinnhuber RO, Henderson MC, Buhler DR. Liver and kidney pathology in rainbow trout (Salmo gairdneri) exposed to dietary pyrrolizidine (Senecio) alkaloids. Exp Mol Pathol 1981; 35:170-83. [PMID: 7286158 DOI: 10.1016/0014-4800(81)90057-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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17
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Chapter 5 Microbial and in Vitro Enzymic Transformation of Alkaloids. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/s1876-0813(08)60240-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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18
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Miranda CL, Cheeke PR, Schmitz JA, Buhler DR. Toxicity of Senecio jacobaea (tansy ragwort) in rats. Toxicol Appl Pharmacol 1980; 56:432-42. [PMID: 7222027 DOI: 10.1016/0041-008x(80)90077-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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