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Liu NN, Jiao N, Tan JC, Wang Z, Wu D, Wang AJ, Chen J, Tao L, Zhou C, Fang W, Cheong IH, Pan W, Liao W, Kozlakidis Z, Heeschen C, Moore GG, Zhu L, Chen X, Zhang G, Zhu R, Wang H. Multi-kingdom microbiota analyses identify bacterial-fungal interactions and biomarkers of colorectal cancer across cohorts. Nat Microbiol 2022; 7:238-250. [PMID: 35087227 PMCID: PMC8813618 DOI: 10.1038/s41564-021-01030-7] [Citation(s) in RCA: 102] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 11/19/2021] [Indexed: 12/19/2022]
Abstract
Despite recent progress in our understanding of the association between the gut microbiome and colorectal cancer (CRC), multi-kingdom gut microbiome dysbiosis in CRC across cohorts is unexplored. We investigated four-kingdom microbiota alterations using CRC metagenomic datasets of 1,368 samples from 8 distinct geographical cohorts. Integrated analysis identified 20 archaeal, 27 bacterial, 20 fungal and 21 viral species for each single-kingdom diagnostic model. However, our data revealed superior diagnostic accuracy for models constructed with multi-kingdom markers, in particular the addition of fungal species. Specifically, 16 multi-kingdom markers including 11 bacterial, 4 fungal and 1 archaeal feature, achieved good performance in diagnosing patients with CRC (area under the receiver operating characteristic curve (AUROC) = 0.83) and maintained accuracy across 3 independent cohorts. Coabundance analysis of the ecological network revealed associations between bacterial and fungal species, such as Talaromyces islandicus and Clostridium saccharobutylicum. Using metagenome shotgun sequencing data, the predictive power of the microbial functional potential was explored and elevated D-amino acid metabolism and butanoate metabolism were observed in CRC. Interestingly, the diagnostic model based on functional EggNOG genes achieved high accuracy (AUROC = 0.86). Collectively, our findings uncovered CRC-associated microbiota common across cohorts and demonstrate the applicability of multi-kingdom and functional markers as CRC diagnostic tools and, potentially, as therapeutic targets for the treatment of CRC.
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Affiliation(s)
- Ning-Ning Liu
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Na Jiao
- National Clinical Research Center for Child Health, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Guangdong Institute of Gastroenterology, Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Colorectal Surgery, the Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Research Institute, GloriousMed Clinical Laboratory Co., Ltd., Shanghai, China
| | - Jing-Cong Tan
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ziliang Wang
- Clinical Medicine Transformation Center and Office of Academic Research, Shanghai Hospital of Traditional Chinese Medicine Affiliated to Shanghai University of traditional Chinese Medicine, Shanghai, China
| | - Dingfeng Wu
- Department of Gastroenterology, The Shanghai Tenth People's Hospital, Department of Bioinformatics, School of Life Sciences and Technology, Tongji University, Shanghai, China
- Bioinformatics Division, GloriousMed Clinical Laboratory Co., Ltd, Shanghai, China
| | - An-Jun Wang
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jie Chen
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Liwen Tao
- Department of Gastroenterology, The Shanghai Tenth People's Hospital, Department of Bioinformatics, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Chenfen Zhou
- Chinese Academy of Sciences Key Laboratory of Computational Biology, Bio-Med Big Data Center, Shanghai Institute of Nutrition and Health, University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Wenjie Fang
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Io Hong Cheong
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Weihua Pan
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Wanqing Liao
- Shanghai Key Laboratory of Molecular Medical Mycology, Department of Dermatology, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - Zisis Kozlakidis
- Laboratory Services and Biobanking, International Agency for Research on Cancer, World Health Organization, Lyon, France
| | - Christopher Heeschen
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Geromy G Moore
- United States Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, USA
| | - Lixin Zhu
- Guangdong Institute of Gastroenterology, Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Colorectal Surgery, the Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
| | - Xingdong Chen
- State Key Laboratory of Genetic Engineering, Human Phenome Institute and School of Life Sciences, Fudan University, Shanghai, China.
- Fudan University Taizhou Institute of Health Sciences, Taizhou, China.
| | - Guoqing Zhang
- Chinese Academy of Sciences Key Laboratory of Computational Biology, Bio-Med Big Data Center, Shanghai Institute of Nutrition and Health, University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China.
| | - Ruixin Zhu
- Research Institute, GloriousMed Clinical Laboratory Co., Ltd., Shanghai, China.
- Department of Gastroenterology, The Shanghai Tenth People's Hospital, Department of Bioinformatics, School of Life Sciences and Technology, Tongji University, Shanghai, China.
- Bioinformatics Division, GloriousMed Clinical Laboratory Co., Ltd, Shanghai, China.
| | - Hui Wang
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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2
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von Schwartzenberg RJ, Bisanz JE, Lyalina S, Spanogiannopoulos P, Ang QY, Cai J, Dickmann S, Friedrich M, Liu SY, Collins SL, Ingebrigtsen D, Miller S, Turnbaugh JA, Patterson AD, Pollard KS, Mai K, Spranger J, Turnbaugh PJ. Caloric restriction disrupts the microbiota and colonization resistance. Nature 2021; 595:272-277. [PMID: 34163067 PMCID: PMC8959578 DOI: 10.1038/s41586-021-03663-4] [Citation(s) in RCA: 98] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 05/21/2021] [Indexed: 12/14/2022]
Abstract
Diet is a major factor that shapes the gut microbiome1, but the consequences of diet-induced changes in the microbiome for host pathophysiology remain poorly understood. We conducted a randomized human intervention study using a very-low-calorie diet (NCT01105143). Although metabolic health was improved, severe calorie restriction led to a decrease in bacterial abundance and restructuring of the gut microbiome. Transplantation of post-diet microbiota to mice decreased their body weight and adiposity relative to mice that received pre-diet microbiota. Weight loss was associated with impaired nutrient absorption and enrichment in Clostridioides difficile, which was consistent with a decrease in bile acids and was sufficient to replicate metabolic phenotypes in mice in a toxin-dependent manner. These results emphasize the importance of diet-microbiome interactions in modulating host energy balance and the need to understand the role of diet in the interplay between pathogenic and beneficial symbionts.
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Affiliation(s)
- Reiner Jumpertz von Schwartzenberg
- Charité Universitätsmedizin Berlin, Department of Endocrinology and Metabolic Diseases, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Center for Cardiovascular Research (CCR), Berlin, Germany
| | - Jordan E Bisanz
- Department of Microbiology & Immunology, University of California San Francisco, San Francisco, CA, USA
| | | | - Peter Spanogiannopoulos
- Department of Microbiology & Immunology, University of California San Francisco, San Francisco, CA, USA
| | - Qi Yan Ang
- Department of Microbiology & Immunology, University of California San Francisco, San Francisco, CA, USA
| | - Jingwei Cai
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Sophia Dickmann
- Charité Universitätsmedizin Berlin, Department of Endocrinology and Metabolic Diseases, Berlin, Germany
| | - Marie Friedrich
- Charité Universitätsmedizin Berlin, Department of Endocrinology and Metabolic Diseases, Berlin, Germany
| | - Su-Yang Liu
- Department of Pathology, University of California San Francisco, San Francisco, CA, USA
| | - Stephanie L Collins
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Danielle Ingebrigtsen
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Steve Miller
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Jessie A Turnbaugh
- Department of Microbiology & Immunology, University of California San Francisco, San Francisco, CA, USA
| | - Andrew D Patterson
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Katherine S Pollard
- Gladstone Institutes, San Francisco, CA, USA
- Department of Epidemiology & Biostatistics, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
- Institute for Computational Health Sciences, University of California San Francisco, San Francisco, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Knut Mai
- Charité Universitätsmedizin Berlin, Department of Endocrinology and Metabolic Diseases, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Joachim Spranger
- Charité Universitätsmedizin Berlin, Department of Endocrinology and Metabolic Diseases, Berlin, Germany.
- Berlin Institute of Health (BIH), Berlin, Germany.
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Center for Cardiovascular Research (CCR), Berlin, Germany.
| | - Peter J Turnbaugh
- Department of Microbiology & Immunology, University of California San Francisco, San Francisco, CA, USA.
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3
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Mishra S, Goyal D, Phurailatpam L. Targeted 16S rRNA gene and ITS2 amplicon sequencing of leaf and spike tissues of Piper longum identifies new candidates for bioprospecting of bioactive compounds. Arch Microbiol 2021; 203:3851-3867. [PMID: 34013420 DOI: 10.1007/s00203-021-02356-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 04/27/2021] [Accepted: 05/03/2021] [Indexed: 12/19/2022]
Abstract
Piper longum (also known as Indian long pepper) is widely used in Ayurvedic, Siddha and Unani medicine systems. The principle bioactive compound of this plant is piperine, which mainly accumulates in the fruits called spikes. The report of piperine production by endophytic microbes isolated from Piper sp., motivated us to investigate the endophytic microbial diversity associated with the spikes vis-à-vis leaves (which contain negligible levels of piperine). This is the first report to use metagenomics approach to unravel the endophytic microbial diversity in P. longum. Our results indicate that 2, 56, 631 bacterial OTUs and 1090 fungal OTUs were picked cumulatively from both the tissues. Although bacterial and fungal endophytes occupy the same niche, remarkable differences exist in their diversity and abundance. For instance, the most abundant bacterial genera in spikes were Nocardioides and Pseudonocardia (Phylum Actinobacteria; reported to produce bioactive compounds); while, in leaves were Larkinella and Hymenobacter (Phylum Bacteriodetes). Likewise, the fungal endophytes, Periconia, Cladosporium and Coniothyrium (which have been earlier reported to produce commercially important metabolites including piperine), were also present in high abundance in spikes, in comparison to leaves. Further, the results of PICRUSt analysis reveal the high metabolic potential of spike-associated bacteria for secondary metabolism, namely biosynthesis of alkaloids (including pyridine/piperidine), terpenes, flavonoids and antibiotics. Therefore, our findings indicate that the endophytes abundant or unique in spikes could be explored for bioprospecting of novel/commercially important metabolites; an approach that has both ecological and economical benefits.
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Affiliation(s)
- Sushma Mishra
- Plant Biotechnology Lab, Department of Botany, Faculty of Science, Dayalbagh Educational Institute (Deemed-to-be-University), Agra, Uttar Pradesh, India.
| | - Deepika Goyal
- Plant Biotechnology Lab, Department of Botany, Faculty of Science, Dayalbagh Educational Institute (Deemed-to-be-University), Agra, Uttar Pradesh, India
| | - Laccy Phurailatpam
- Plant Biotechnology Lab, Department of Botany, Faculty of Science, Dayalbagh Educational Institute (Deemed-to-be-University), Agra, Uttar Pradesh, India
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4
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Wibowo MC, Yang Z, Borry M, Hübner A, Huang KD, Tierney BT, Zimmerman S, Barajas-Olmos F, Contreras-Cubas C, García-Ortiz H, Martínez-Hernández A, Luber JM, Kirstahler P, Blohm T, Smiley FE, Arnold R, Ballal SA, Pamp SJ, Russ J, Maixner F, Rota-Stabelli O, Segata N, Reinhard K, Orozco L, Warinner C, Snow M, LeBlanc S, Kostic AD. Reconstruction of ancient microbial genomes from the human gut. Nature 2021; 594:234-239. [PMID: 33981035 PMCID: PMC8189908 DOI: 10.1038/s41586-021-03532-0] [Citation(s) in RCA: 105] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/12/2021] [Indexed: 12/26/2022]
Abstract
Loss of gut microbial diversity1–6 in industrial populations is associated with chronic diseases7, underscoring the importance of studying our ancestral gut microbiome. However, relatively little is known about the composition of pre-industrial gut microbiomes. Here we performed a large-scale de novo assembly of microbial genomes from palaeofaeces. From eight authenticated human palaeofaeces samples (1,000–2,000 years old) with well-preserved DNA from southwestern USA and Mexico, we reconstructed 498 medium- and high-quality microbial genomes. Among the 181 genomes with the strongest evidence of being ancient and of human gut origin, 39% represent previously undescribed species-level genome bins. Tip dating suggests an approximate diversification timeline for the key human symbiont Methanobrevibacter smithii. In comparison to 789 present-day human gut microbiome samples from eight countries, the palaeofaeces samples are more similar to non-industrialized than industrialized human gut microbiomes. Functional profiling of the palaeofaeces samples reveals a markedly lower abundance of antibiotic-resistance and mucin-degrading genes, as well as enrichment of mobile genetic elements relative to industrial gut microbiomes. This study facilitates the discovery and characterization of previously undescribed gut microorganisms from ancient microbiomes and the investigation of the evolutionary history of the human gut microbiota through genome reconstruction from palaeofaeces. Ancient microbiomes from palaeofaeces are more similar to non-industrialized than industrialized human gut microbiomes regardless of geography, but 39% of their de novo reconstructed genomes represent previously undescribed microbial species.
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Affiliation(s)
- Marsha C Wibowo
- Section on Pathophysiology and Molecular Pharmacology, Joslin Diabetes Center, Boston, MA, USA.,Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Zhen Yang
- Section on Pathophysiology and Molecular Pharmacology, Joslin Diabetes Center, Boston, MA, USA.,Department of Microbiology, Harvard Medical School, Boston, MA, USA.,Department of Combinatorics and Optimization, University of Waterloo, Waterloo, Ontario, Canada
| | - Maxime Borry
- Department of Archaeogenetics, Max Planck Institute for the Science of Human History, Jena, Germany
| | - Alexander Hübner
- Department of Archaeogenetics, Max Planck Institute for the Science of Human History, Jena, Germany
| | - Kun D Huang
- CIBIO Department, University of Trento, Trento, Italy.,Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy
| | - Braden T Tierney
- Section on Pathophysiology and Molecular Pharmacology, Joslin Diabetes Center, Boston, MA, USA.,Department of Microbiology, Harvard Medical School, Boston, MA, USA.,Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Samuel Zimmerman
- Section on Pathophysiology and Molecular Pharmacology, Joslin Diabetes Center, Boston, MA, USA.,Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Francisco Barajas-Olmos
- Immunogenomics and Metabolic Diseases Laboratory, Secretaría de Salud, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Cecilia Contreras-Cubas
- Immunogenomics and Metabolic Diseases Laboratory, Secretaría de Salud, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Humberto García-Ortiz
- Immunogenomics and Metabolic Diseases Laboratory, Secretaría de Salud, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Angélica Martínez-Hernández
- Immunogenomics and Metabolic Diseases Laboratory, Secretaría de Salud, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Jacob M Luber
- Section on Pathophysiology and Molecular Pharmacology, Joslin Diabetes Center, Boston, MA, USA.,Department of Microbiology, Harvard Medical School, Boston, MA, USA.,Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Philipp Kirstahler
- Research Group for Genomic Epidemiology, National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Tre Blohm
- Department of Anthropology, University of Montana, Missoula, MT, USA
| | - Francis E Smiley
- Department of Anthropology, Northern Arizona University, Flagstaff, AZ, USA
| | - Richard Arnold
- Pahrump Paiute Tribe and Consolidated Group of Tribes and Organizations, Pahrump, NV, USA
| | - Sonia A Ballal
- Department of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Boston, MA, USA
| | - Sünje Johanna Pamp
- Research Group for Genomic Epidemiology, National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Julia Russ
- Morrison Microscopy Core Research Facility, Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Frank Maixner
- Institute for Mummy Studies, EURAC Research, Bolzano, Italy
| | - Omar Rota-Stabelli
- Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy.,Center Agriculture Food Environment (C3A), University of Trento, Trento, Italy
| | - Nicola Segata
- CIBIO Department, University of Trento, Trento, Italy
| | - Karl Reinhard
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Lorena Orozco
- Immunogenomics and Metabolic Diseases Laboratory, Secretaría de Salud, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Christina Warinner
- Department of Archaeogenetics, Max Planck Institute for the Science of Human History, Jena, Germany.,Department of Anthropology, Harvard University, Cambridge, MA, USA.,Faculty of Biological Sciences, Friedrich-Schiller University, Jena, Germany
| | - Meradeth Snow
- Department of Anthropology, University of Montana, Missoula, MT, USA
| | - Steven LeBlanc
- Peabody Museum of Archaeology and Ethnology, Harvard University, Cambridge, MA, USA
| | - Aleksandar D Kostic
- Section on Pathophysiology and Molecular Pharmacology, Joslin Diabetes Center, Boston, MA, USA. .,Department of Microbiology, Harvard Medical School, Boston, MA, USA.
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5
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Kazemian N, Ramezankhani M, Sehgal A, Khalid FM, Kalkhoran AHZ, Narayan A, Wong GKS, Kao D, Pakpour S. The trans-kingdom battle between donor and recipient gut microbiome influences fecal microbiota transplantation outcome. Sci Rep 2020; 10:18349. [PMID: 33110112 PMCID: PMC7591866 DOI: 10.1038/s41598-020-75162-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 10/12/2020] [Indexed: 01/29/2023] Open
Abstract
Fundamental restoration ecology and community ecology theories can help us better understand the underlying mechanisms of fecal microbiota transplantation (FMT) and to better design future microbial therapeutics for recurrent Clostridioides difficile infections (rCDI) and other dysbiosis-related conditions. In this study, stool samples were collected from donors and rCDI patients one week prior to FMT (pre-FMT), as well as from patients one week following FMT (post-FMT). Using metagenomic sequencing and machine learning, our results suggested that FMT outcome is not only dependent on the ecological structure of the recipients, but also the interactions between the donor and recipient microbiomes at the taxonomical and functional levels. We observed that the presence of specific bacteria in donors (Clostridioides spp., Desulfovibrio spp., Odoribacter spp. and Oscillibacter spp.) and the absence of fungi (Yarrowia spp.) and bacteria (Wigglesworthia spp.) in recipients prior to FMT could predict FMT success. Our results also suggested a series of interlocked mechanisms for FMT success, including the repair of the disturbed gut ecosystem by transient colonization of nexus species followed by secondary succession of bile acid metabolizers, sporulators, and short chain fatty acid producers.
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Affiliation(s)
- Negin Kazemian
- School of Engineering, University of British Columbia, Kelowna, BC, Canada
| | - Milad Ramezankhani
- School of Engineering, University of British Columbia, Kelowna, BC, Canada
| | - Aarushi Sehgal
- Department of Computer Science and Engineering, National Institute of Technology, Hamirpur, Himachal Pradesh, India
| | | | | | - Apurva Narayan
- Department of Computer Science, University of British Columbia, Kelowna, BC, Canada
| | - Gane Ka-Shu Wong
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Department of Medicine, University of Alberta, Edmonton, AB, Canada.,BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen, China
| | - Dina Kao
- Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
| | - Sepideh Pakpour
- School of Engineering, University of British Columbia, Kelowna, BC, Canada.
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6
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Sohn JH, Han MJ, Lee MY, Kang SK, Yang JS. Simultaneous determination of N-hydroxymethyl-N-methylformamide, N-methylformamide and N-acetyl-S-(N-methylcarbamoyl)cystein in urine samples from workers exposed to N,N-dimethylformamide by liquid chromatography-tandem mass spectrometry. J Pharm Biomed Anal 2005; 37:165-70. [PMID: 15664757 DOI: 10.1016/j.jpba.2004.10.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Revised: 09/30/2004] [Accepted: 10/02/2004] [Indexed: 11/21/2022]
Abstract
N-Hydroxymethyl-N-methylformamide (HMMF) and N-methylformamide (NMF) in urine samples from workers exposed to N,N-dimethylformamide (DMF) cannot be distinguished by a gas chromatographic method because HMMF is converted to NMF at the injection port of gas chromatography (GC). Total NMF (HMMF+NMF) has been measured instead. Also, the determination of N-acetyl-S-(N-methylcarbamoyl)cystein (AMCC), which is supposed to be related to the toxicity of DMF, needs multiple treatments to convert to a volatile compound before GC analysis. There is no previous report of a simultaneous determination of three major metabolites of DMF in urine. The aim of this study is to develop a simple and selective method for the determination of DMF metabolite in urine. By using a liquid chromatography-tandem mass spectrometry, we can directly distinguish these three major metabolites of DMF in a single run. The diluted urine samples were analyzed on Capcell Pak MF SG80 column with the mobile phase of methanol in 2mM formic acid (10:90, v/v). The analytes were detected by an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curves were linear (r>0.999) over the concentration ranges of 0.004-8 microg/mL. The precision and accuracy of quality control samples for inter-batch (n=6) analyses were in the range of 1.3-9.8% and 94.7-116.8, respectively. The sum of each HMMF and NMF concentration determined by LC-MS/MS method shows high correlation (r=0.9927 with the slope of 1.0415, p<0.0001) with NMF included HMMF concentration determined by GC method for 13 urine samples taken from workers exposed to DMF. The excretion ratio of HMMF:NMF:AMCC is approximately 4:1:1 in molar concentration.
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Affiliation(s)
- Jae Ho Sohn
- Phillips Exeter Academy, Exeter, NH 03833-2460, USA
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7
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Chang HY, Tsai CY, Lin YQ, Shih TS, Lin WC. Total body burden arising from a week's repeated dermal exposure to N,N-dimethylformamide. Occup Environ Med 2005; 62:151-6. [PMID: 15723879 PMCID: PMC1740980 DOI: 10.1136/oem.2004.016089] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Hazardous chemicals and their metabolites may accumulate in the body following repeated airborne exposures and skin contact. AIMS To estimate the contribution of skin absorption to total body burden of N,N-dimethylformamide (DMF) across a working week in two groups with similar levels of respiratory exposure but dissimilar skin contact. METHODS Twenty five workers in a synthetic leather (SL) factory, 20 in a copper laminate circuit board (CLCB) factory, and 20 age and sex matched non-DMF exposed subjects, were recruited. Environmental monitoring of DMF exposure via respiratory and dermal routes, as well as biological monitoring of pre-shift urinary N-methylformamide (U-NMF), were performed for five consecutive working days. RESULTS Environmental and biological monitoring showed no detectable exposure in controls. The average airborne DMF concentration (geometric mean (GM) 3.98 ppm, geometric standard deviation (GSD) 1.91 ppm), was insignificantly lower for SL workers than for CLCB workers (GM 4.49, GSD 1.84 ppm). Dermal DMF exposure and U-NMF values, however, were significantly higher for SL workers. A significant pattern of linear accumulation was found across a five day work cycle for SL workers but not for CLCB workers. CONCLUSIONS Dermal exposure to DMF over five consecutive days of occupational exposure can result in the accumulation of a significant DMF body burden. The long term exposure response under both repeated and intermittent conditions of substantial skin exposure is worthy of note.
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Affiliation(s)
- H-Y Chang
- Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, 138 Sheng-Li Road, Tainan 704, Taiwan.
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8
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Chang HY, Yun YD, Yu YC, Shih TS, Lin MS, Kuo HW, Chen KM. The effects of simultaneous exposure to methyl ethyl ketone and toluene on urinary biomarkers of occupational N,N-dimethylformamide exposure. Toxicol Lett 2005; 155:385-95. [PMID: 15649622 DOI: 10.1016/j.toxlet.2004.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2004] [Revised: 11/07/2004] [Accepted: 11/15/2004] [Indexed: 11/19/2022]
Abstract
General regulations and risk assessment regarding toxicants are single-compound oriented even though humans are exposed to multi-chemicals in the general environment. This study investigated the effects of different levels of N,N-dimethylformamide (DMF) and co-exposure levels of methyl ethyl ketone (MEK) and toluene (TOL) on two biomarkers of DMF exposure: non-metabolized urinary (U-)DMF and the DMF metabolite urinary N-methylformamide (NMF). Thirty-five workers were selected from a two-stage field investigation strategy and were classified into four groups based on DMF exposure and co-exposure levels. Breathing-zone air concentrations of DMF, MEK, and TOL as well as dermal DMF exposure were determined. Post-shift U-DMF and U-NMF levels were determined for each individual. U-DMF concentrations were significantly higher in high-DMF groups than in low-DMF groups, but U-NMF concentrations were significantly (P<0.05) lower in the high-DMF-high-co-exposure group than in the high-DMF-low-co-exposure group; there were no significant differences between two low-DMF groups. The ratio of U-NMF to U-DMF showed the biotransformation from DMF to NMF was significantly suppressed at high co-exposure (P<0.001) for high-DMF exposure groups, possibly because of competitive inhibition of CYP2E1, the responsible enzyme involved. Due to the ubiquity of MEK/TOL in DMF-exposed occupational settings, the biological exposure index for occupational DMF exposure should be re-evaluated at high co-exposure levels.
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Affiliation(s)
- Ho-Yuan Chang
- Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, 138 Sheng-Li Road, Tainan 70428, Taiwan.
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9
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Chang HY, Tsai CY, Lin YQ, Shih TS, Lin YC. Urinary biomarkers of occupational N,N-dimethylformamide (DMF) exposure attributed to the dermal exposure. JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY 2004; 14:214-21. [PMID: 15141150 DOI: 10.1038/sj.jea.7500316] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
OBJECTIVE To evaluate whether the dermal exposure to N,N-dimethylformamide (DMF) exerts significant effects and to determine the unit increment of dermal exposure on the total body burden of two biomarkers in urine: metabolism-required N-methylformamide (U-NMF) and non-metabolized DMF (U-DMF) in actual occupational environments. METHODS Exposure via respiratory and dermal routes was assessed on an individual basis for 75 workers from four DMF-related factories directly exposed to DMF. Respiratory exposure was determined by breathing-zone sampling for a full-work shift, and dermal exposure was assessed on the palms and forearms of both hands by an adhesive tape-patch method. U-NMF and U-DMF collected immediately postshift were measured. RESULTS The average concentrations of airborne DMF, DMF on hands and on forearms, U-NMF, and U-DMF (GM) were 1.51 ppm, 0.04 microg/cm(2), 0.03 microg/cm(2), 0.47 mg/l, and 0.38 mg/l, respectively. In multiple linear regression tests, only airborne DMF and DMF on hands remained significantly (P<0.001) associated with U-NMF and U-DMF. Based on model estimates, the unit increment of hands' exposure (microg/cm(2)) could contribute to 0.53 and 0.46 mg/l of the increment of U-NMF and U-DMF, respectively, given a daily occupational airborne exposure to DMF at about 1.5 ppm. CONCLUSIONS Dermal exposure provides a substantial contribution to the total body burden of DMF. A control remedy such as the enforcement of wearing impermeable gloves by workers occupationally exposed to DMF should be implemented with the highest priority.
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Affiliation(s)
- Ho-Yuan Chang
- Graduate Institute of Environmental and Occupational Health, College of Medicine, National Cheng Kung University Medical College, 138 Sheng-Li Road, Tainan 704, Taiwan.
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10
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Chang HY, Shih TS, Cheng CC, Tsai CY, Lai JS, Wang VS. The effects of co-exposure to methyl ethyl ketone on the biological monitoring of occupational exposure to N,N-dimethylformamide. Int Arch Occup Environ Health 2003; 76:121-8. [PMID: 12733084 DOI: 10.1007/s00420-002-0371-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2001] [Accepted: 06/14/2002] [Indexed: 10/25/2022]
Abstract
OBJECTIVES (1) To assess whether urinary N,N-dimethylformamide (U-DMF) is suitable as a biomarker when co-exposure to methyl ethyl ketone (MEK) exists, and to evaluate whether it is suitable as an exposure biomarker of DMF. (2) To examine whether the co-exposure to MEK affects the characteristics of U-NMF and U-DMF. (3) To investigate if the difference in creatinine-adjusted and non-adjusted measurements of urinary biomarkers of DMF exposure is substantial. METHODS Personal exposure monitoring of N,N-dimethylformamide (DMF) and MEK on 11 synthetic-leather workers was performed for 5 consecutive days. Daily post-shift urine for each individual was collected and was analyzed for urinary N-methylformamide (U-NMF) and U-DMF levels on both non-adjusted and creatinine-adjusted bases. RESULTS Both U-NMF and U-DMF showed significant associations with airborne DMF. Positive and significant associations between U-NMF and U-DMF on either a non-adjusted basis or a creatinine-adjusted basis were found. Satisfactory linear associations ( P<0.01) between all kinds of urinary biomarkers and DMF exposure were found. The co-exposure to MEK exerted more effect on the relationship of airborne DMF to U-DMF than to U-NMF. CONCLUSIONS U-DMF is detectable when occupational DMF exposure is near or below the occupational exposure limit of 10 ppm. In view of the performance of sensitivity, specificity, and positive predictive value, U-NMF, in general, is superior to U-DMF. However, on a par with other findings in this and previous studies, U-DMF might be considered as a complimentary biomarker of exposure to DMF in addition to U-NMF. No distinction between creatinine-adjustment or non-adjustment for urine specimens was found in the biological monitoring of DMF exposure. Further exploration of the influence of co-exposure to MEK at higher exposure is warranted.
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Affiliation(s)
- Ho-Yuan Chang
- Graduate Institute of Environmental and Occupational Health, College of Medicine, National Cheng Kung University Medical College, Tainan, Taiwan
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11
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Imbriani M, Negri S, Ghittori S, Maestri L. Measurement of urinary N-acetyl-S-(N-methylcarbamoyl)cysteine by high-performance liquid chromatography with direct ultraviolet detection. J Chromatogr B Analyt Technol Biomed Life Sci 2002; 778:231-6. [PMID: 12376130 DOI: 10.1016/s0378-4347(01)00453-4] [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: 11/28/2022]
Abstract
A new high-performance liquid chromatographic (HPLC) method is described for the determination of urinary N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC), the final product of the conjugation reaction between a metabolic intermediate of N,N-dimethylformamide (DMF) and glutathione. Urine samples were purified by C(18) solid-phase extraction and then directly analysed by HPLC with an Aminex Ion Exclusion HPX-87H column maintained at 25 degrees C and a UV detector set at 196 nm. Under isocratic conditions (2.4 mM sulphuric acid, flow-rate=0.6 ml/min) AMCC eluted at 20.2 min. The reproducibility (C.V.%) was 1.3-2.7% (intra- and inter-assay, N = 5); the accuracy was 98.0+/-1.7% at 10 mg/l and 101.9+/-1.5% at 800 mg/l (mean+/-SD, N = 3). AMCC was measured in urine from 22 exposed subjects. A strong correlation was found between AMCC and environmental DMF [AMCC (mg/g creatinine)=3.40xDMF (mg/m(3)) + 3.07; r=0.95], while in the urine of 20 unexposed subjects the concentration of AMCC was constantly below the detection limit of the method (0.9 mg/l in urine). The method described appears to be useful for the biological monitoring of DMF exposure.
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Affiliation(s)
- Marcello Imbriani
- Dipartimento di Medicina Preventiva, Occupazionale e di Comunita': II Sezione di Medicina del Lavoro, Pavia, Italy
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12
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Mráz J, Dusková S, Gálová E, Nohová H, Krausová P, Linhart I, Simek P. Improved gas chromatographic-mass spectrometric determination of the N-methylcarbamoyl adduct at the N-terminal valine of globin, a metabolic product of the solvent N,N-dimethylformamide. J Chromatogr B Analyt Technol Biomed Life Sci 2002; 778:357-65. [PMID: 12376140 DOI: 10.1016/s0378-4347(01)00455-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A sensitive method for determination of the N-methylcarbamoyl adduct at the N-terminal valine of globin, a new metabolic product of the industrial solvent N,N-dimethylformamide (DMF), has been developed and validated. The method includes conversion of the adduct by the Edman degradation to 3-methyl-5-isopropylhydantoin (MVH), which is followed by optimized gas chromatographic analysis with mass spectrometric detection at m/z 114. The recovery of MVH from terminal N-methylcarbamoylvaline was determined using a model dipeptide to be 90%. Calibration of the method is done with MVH, employing 3-methyl-5-isobutylhydantoin as the internal standard. The limit of detection is 0.2 nmol MVH/g globin when a 100-mg sample is used. Within- and between-day precision is 4-10%. The method has been used to determine the background levels of MVH in unexposed subjects. Further, toxicokinetic studies in volunteers laid the grounds for setting the reference value for biological monitoring of occupational exposure to DMF.
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Affiliation(s)
- Jaroslav Mráz
- Centre of Industrial Hygiene and Occupational Diseases, National Institute of Public Health, Srobárova 48, 100 42 Prague, Czech Republic.
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13
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Tolando R, Zanovello A, Ferrara R, Iley JN, Manno M. Inactivation of rat liver cytochrome P450 (P450) by N,N-dimethylformamide and N,N-dimethylacetamide. Toxicol Lett 2001; 124:101-11. [PMID: 11684362 DOI: 10.1016/s0378-4274(01)00384-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
N,N-dimethylformamide (DMF), an organic solvent widely used in industry, is bioactivated by cytochrome P450 (P450) to reactive metabolites which are believed to be responsible for the hepatotoxicity observed in animals and humans. A decrease of the activating enzyme has been reported in rats treated with DMF, although the specific P450 isoform(s) involved and the nature of the reactive species responsible for this and the other toxic effects are still being investigated. In the present work, the effect of DMF and of the structurally related N,N-dimethylacetamide (DMAc) on the activating enzyme and the nature of the reactive species involved in the mechanism of P450 inactivation by the two chemicals were investigated in vitro. Incubation of liver microsomes from pyridine-induced rats with either substrate resulted in a dose-dependent (0-20 mM) loss of P450 (up to 28 and 24% for DMF and DMAc, respectively), microsomal haem (up to 24 and 20% for DMF and DMAc, respectively), but not protoporphyrin IX content. Moreover, bubbling of CO through the incubation mixture gave almost complete protection against substrate-dependent P450 inactivation, and the spin trapping agent N-tert-butyl-alpha-phenylnitrone, but neither glutathione nor vitamin C, provided a significant protection against DMF- or DMAc-dependent haem loss. Finally, electron spin resonance analysis of microsomal incubations in presence of DMF or DMAc showed spectral evidence for a carbon centered radical intermediate. The results indicate, overall, that both compounds are metabolized in vitro by P450, probably CYP2E1, to free radical metabolites which attack the haem prosthetic group, leading to suicidal enzyme inactivation.
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Affiliation(s)
- R Tolando
- Institute of Occupational Medicine, University of Padua, Via Facciolati, 71, Padua 35128, Italy
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14
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Käfferlein HU, Angerer J. Simultaneous determination of two human urinary metabolites of N,N-dimethylformamide using gas chromatography-thermionic sensitive detection with mass spectrometric confirmation. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1999; 734:285-98. [PMID: 10595726 DOI: 10.1016/s0378-4347(99)00372-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Two human urinary metabolites of the industrial solvent N,N-dimethylformamide (DMF), N-hydroxymethyl-N-methylformamide (HMMF) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC), were assayed using a new analytical method (gas chromatography and thermionic sensitive detection). Clean-up of urine samples includes a liquid-liquid extraction step followed by a solid-phase extraction step to separate HMMF and AMCC from other urine components. During clean-up, AMCC is converted into ethyl-N-methylcarbamate (EMC), and during gas chromatography, HMMF is degraded in the injector to N-methylformamide (NMF). All the validation data necessary for a quantitative procedure are given. The method was applied to urine samples from workers exposed to DMF and from the general population. The results were confirmed by mass spectrometric determination. For this purpose a further liquid-liquid extraction step was introduced in the clean-up procedure. Background levels of AMCC in the general population were identified.
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Affiliation(s)
- H U Käfferlein
- Institut und Poliklinik für Arbeits, Sozial- und Umweltmedizin der Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
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15
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Lareo AC, Perico A, Bavazzano P, Soave C, Perbellini L. Biological monitoring of workers exposed to N, N-dimethylfomamide. I. Methods of analysis. Int Arch Occup Environ Health 1995; 67:41-6. [PMID: 7622278 DOI: 10.1007/bf00383131] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Some methods for analysing N,N-dimethylformamide and its metabolites [hydroxymethyl-N-methylformamide, hydroxymethylformamide and N-acetyl-S-(N-methylcarbamoyl)cysteine] in the urine of exposed workers are described. Unchanged dimethylformamide was measured after pretreatment of urine (2 ml) with silica gel cartridges and elution with methanol. The gas chromatographic analysis using a nitrogen phosphor detector made it possible to detect N,N-dimethylformamide in urine even when workers were exposed to low concentrations of the solvent (about 1 mg/m3). N-Hydroxymethyl-N-methylformamide and N-hydroxymethylformamide were analysed as N-methylformamide and formamide respectively after direct injection of urine into the gas chromatograph. The injection port temperature played an important role in the gas chromatographic determination of these products. Reliable results were obtained when direct or split injections were performed at 250 degrees C. The splitless injection gave the same reliable results at 150 degrees C. In urine samples from occupationally non-exposed persons, N-methylformamide could not be detected. In contrast, formamide (or its precursor, hydroxymethylformamide) was present in every urine sample. Our results in respect of 19 urine samples analysed with the injection port of the gas chromatograph at 250 degrees C gave a mean of 8.6 mg/l of formamide. N-Acetyl-S-(N-methylcarbamoyl)cysteine was determined using a modified method for analysing organic acid in urine samples. The metabolite was extracted with ethyl ether in an acid environment, treated with a silylating reagent and measured by gas chromatography/mass spectrometry.
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Affiliation(s)
- A C Lareo
- Institute of Occupational Medicine, Policlinico Borgo Roma, Verona, Italy
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16
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Van den Bulcke M, Rosseel MT, Wijnants P, Buylaert W, Belpaire FM. Metabolism and hepatotoxicity of N,N-dimethylformamide, N-hydroxymethyl-N-methylformamide, and N-methylformamide in the rat. Arch Toxicol 1994; 68:291-5. [PMID: 8085939 DOI: 10.1007/s002040050071] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The metabolism and hepatotoxicity of N,N-dimethylformamide (DMF) and two of its metabolites, N-hydroxymethyl-N-methylformamide (HMMF) and N-methylformamide (NMF) were evaluated over a 4-day period in rats. DMF toxicity was dose dependent and delayed toxicity after the administration of a high DMF dose (13.7 mmol/kg) in comparison to a lower dose (4.1 mmol/kg) was observed. Treatment of rats with 13.7 mmol/kg DMF, HMMF, or NMF showed i) that DMF is more toxic than HMMF or NMF, and ii) that hepatotoxicity occurs later for DMF than for HMMF or NMF. Analysis of serum and urine samples demonstrated that DMF is first metabolized to HMMF, which is then partially converted to NMF. After HMMF administration, NMF was found both in serum and in urine. The time course of DMF and HMMF toxicity in relation to NMF formation fitted the hypothesis that the hepatotoxicity of DMF and HMMF is mediated via NMF. The degree of hepatotoxicity after HMMF and NMF treatment is similar. However, the degree of DMF hepatotoxicity is much higher than in the case of NMF or HMMF. The role of NMF as an obligatory intermediate in DMF and HMMF hepatotoxicity is discussed.
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Affiliation(s)
- M Van den Bulcke
- Heymans Institute of Pharmacology, University of Ghent Medical School, Belgium
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17
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Rosseel MT, Belpaire FM, Samijn N, Wijnant P. Simultaneous determination of N,N-dimethylformamide, N-monomethylformamide and N-hydroxymethyl-N-methylformamide in rat plasma by capillary gas chromatography. JOURNAL OF CHROMATOGRAPHY 1993; 615:154-8. [PMID: 8340454 DOI: 10.1016/0378-4347(93)80302-k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A capillary gas chromatographic method with nitrogen-phosphorus detection for the simultaneous quantitative determination of N,N-dimethylformamide, and its two metabolites, N-monomethylformamide and N-hydroxymethyl-N-methylformamide, in rat plasma has been developed. The method involves a single extraction step with ethyl acetate-acetone (4:1, v/v). The extract is injected into a fused-silica capillary column coated with Carbowax 20M. A temperature gradient (65-110 degrees C) is applied, and the three products can be separated within 10 min. The quantitation limits, using 25 microliters of rat plasma, for N,N-dimethylformamide, N-monomethylformamide and N-hydroxymethyl-N-methylformamide are 0.4, 0.4 and 2 micrograms/ml, respectively. This method is suitable for toxicokinetic studies in rats.
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Affiliation(s)
- M T Rosseel
- Heymans Institute of Pharmacology, University of Ghent Medical School, Belgium
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18
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Hundley SG, McCooey KT, Lieder PH, Hurtt ME, Kennedy GL. Dimethylformamide pharmacokinetics following inhalation exposure in monkeys. Drug Chem Toxicol 1993; 16:53-79. [PMID: 8436077 DOI: 10.3109/01480549309038661] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Male and female cynomolgus monkeys received whole-body inhalation exposures to dimethylformamide (DMF) at concentrations of 30, 100, and 500 ppm for 6 hours a day, 5 days a week over a 13-week period. Serial blood samples were drawn at the conclusion of the first day of exposure and following 15, 29, 57, and 85 days of testing. Area under the plasma concentration curve (AUC) values were determined for DMF and "NMF" [N-methylformamide (NMF) plus N-(hydroxymethyl)-N-methylformamide (DMF-OH)]. Urine samples were also collected and assayed for DMF, NMF and DMF-OH. The systemic exposure to DMF increased disproportionately as the airborne DMF concentrations increased. DMF AUC values increased 19- to 37-fold in male and 35- to 54-fold in female monkeys as the inhalation concentrations increased 5-fold (100 to 500 ppm). These data are consistent with saturation of DMF metabolism as inhaled DMF concentrations increased from 100 to 500 ppm. AUC values, peak plasma concentrations, and plasma half-lives were essentially unaltered over the duration of the study within each exposure concentration tested. Estimated plasma half-lives ranged from 1 to 2 hours and 4 to 15 hours for DMF and "NMF" respectively. DMF was rapidly converted to "NMF" following 30 ppm exposures, with "NMF" plasma concentrations higher than DMF plasma concentrations at the 0.5 hour time-point. In plasma samples simultaneously assayed for DMF-OH and NMF, the concentration of DMF-OH exceeded, was equal to, or was less than NMF concentrations depending upon the plasma sample. DMF-OH was always the main urinary metabolite (56 to 95 percent) regardless of exposure level or time on study.
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Affiliation(s)
- S G Hundley
- E. I. du Pont de Nemours & Company, Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Newark, Delaware 19714
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19
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Hundley SG, Lieder PH, Valentine R, Malley LA, Kennedy GL. Dimethylformamide pharmacokinetics following inhalation exposures to rats and mice. Drug Chem Toxicol 1993; 16:21-52 sW. [PMID: 8436076 DOI: 10.3109/01480549309038660] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Whole-body inhalation exposures to N,N-dimethylformamide (DMF) were conducted with rats and mice. The exposure concentrations were 10, 250, and 500 ppm DMF. The exposure routines consisted of single 1-, 3-, or 6-hour exposures and ten 6-hour exposures (ten exposure days in 2 weeks). Area under the plasma concentration curve (AUC) values were determined following exposure for DMF and "N-methylformamide" ["NMF" represented N-methylformamide plus N-(hydroxymethyl)-N-methylformamide (DMF-OH)]. The DMF AUC values increased 8- and 29-fold for rats and mice, respectively, following single six-hour exposures to 250 and 500 ppm DMF. These data are indicative of saturation of DMF metabolism. Peak "NMF" plasma concentrations for rats and mice, following single 6-hour exposures, did not increase as DMF exposure concentrations increased from 250 to 500 ppm. In addition, the "NMF" plasma levels in rats following a single 6-hour 500 ppm DMF exposure did not decay by 24 hours post exposure. These "NMF" plasma data also indicate saturation of DMF metabolism. Multiple exposures to 500 ppm DMF resulted in a 3- and 4-fold reduction in DMF AUC values for rats and mice, respectively, compared to AUC values following a single six-hour 500 ppm DMF exposure. This indicates enhanced metabolism of DMF resulting from multiple 500 ppm DMF exposures and together with saturation of DMF metabolism suggest using exposure levels below 500 ppm in a chronic bioassay. Selected plasma samples were simultaneously assayed for NMF and DMF-OH. The "NMF" values consisted of between 30 to 60 percent DMF-OH depending upon the exposure group (conversely NMF represented 30 to 60 percent of the "NMF" levels). Urinary analysis of all samples revealed DMF-OH represented over 90 percent of the summed DMF, DMF-OH and NMF quantities.
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Affiliation(s)
- S G Hundley
- E. I. du Pont de Nemours & Company, Inc., Haskell Laboratory for Toxicology and Industrial Medicine, Newark, Delaware 19714
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20
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Santoni G, Bavazzano P, Perico A, Colzi A, Benassi S, Medica A, La Morgia R, Giuliano G. High-performance liquid chromatographic determination of N-methylformamide and N-methyl-N-(hydroxymethyl)-formamide in human urine. JOURNAL OF CHROMATOGRAPHY 1992; 581:287-92. [PMID: 1452621 DOI: 10.1016/0378-4347(92)80284-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A reliable high-performance liquid chromatographic (HPLC) method which allows the determination in human urine of two important metabolites of N,N-dimethylformamide (DMF), namely N-methylformamide (MMF) and N-methyl-N-(hydroxymethyl)formamide (DMFOH), is reported. A single-step rapid purification of urine was performed on a C18 solid-phase extraction column and the eluate was injected directly on to the HPLC column. HPLC was carried out isocratically on Aminex Ion Exclusion HPX-87H column using 7.5.10(-4) M sulphuric acid as the mobile phase with ultraviolet detection at 196 nm. The method is specific, accurate, precise and sufficiently sensitive to be applied to the biological monitoring of MMF and DMFOH in workers exposed to DMF.
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Affiliation(s)
- G Santoni
- Military Chemical Pharmaceutic Institute, Florence, Italy
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21
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Mráz J, Nohová H. Absorption, metabolism and elimination of N,N-dimethylformamide in humans. Int Arch Occup Environ Health 1992; 64:85-92. [PMID: 1399028 DOI: 10.1007/bf00381474] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Excretion of N,N-dimethylformamide (DMF) and DMF metabolites N-hydroxymethyl-N-methylformamide ("MF"), N-hydroxymethyl-formamide ("F") and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) has been monitored in the urine of volunteers during and after their 8-h exposure to DMF vapour at a concentration of 10, 30 and 60 mg.m-3. The pulmonary ventilation in these experiments was typically about 10 l.min-1 and the retention in the respiratory tract was 90%. After exposure to 30mg DMF.m-3, the yield of compound determined in the urine represented 0.3% (DMF), 22.3% ("MF"), 13.2% ("F") and 13.4% (AMCC) of the dose absorbed via the respiratory tract. The excretion curves of the particular compounds attained their maximum 6-8h (DMF), 6-8h ("MF"), 8-14h ("F") and 24-34h (AMCC) after the start of the exposure. The half-times of excretion were approximately 2, 4, 7 and 23 h respectively. In contrast to slow elimination of AMCC after exposure to DMF, AMCC was eliminated rapidly after AMCC intake. This discrepancy could be explained by rate-limiting reversible protein binding of a reactive metabolic intermediate of DMF, possibly methylisocyanate.
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Affiliation(s)
- J Mráz
- Institute of Hygiene and Epidemiology, Prague, Czechoslovakia
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Kawai T, Yasugi T, Mizunuma K, Watanabe T, Cai SX, Huang MY, Xi LQ, Qu JB, Yao BZ, Ikeda M. Occupational dimethylformamide exposure. 2. Monomethylformamide excretion in urine after occupational dimethylformamide exposure. Int Arch Occup Environ Health 1992; 63:455-60. [PMID: 1577524 DOI: 10.1007/bf00572111] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The relationship between the 8-h time-weighted average (TWA) intensity of exposure to N,N-dimethylformamide (DMF) vapor (with little possibility of skin contact with liquid DMF) and the subsequent excretion of N-monomethylformamide (MMF) precursor in shift-end urine samples was examined in 116 workers exposed to DMF and 92 workers exposed to DMF in combination with toluene. Urinary MMF level was examined also in 42 non-exposed subjects. The TWA vapor concentration in breathing zone air of each worker was successfully measured by means of a recently developed diffusive sampler in which water was used as an absorbent. The examination of gas chromatographic (GC) conditions for MMF determination showed that the formation of MMF was not saturated when the injection port temperature was set at 200 degrees C, reached a plateau at 250 degrees C, and showed no additional increase at 300 degrees C. There was a linear relationship between DMF in air and MMF in urine with a regression equation of y = 1.65 x + 1.69 (r = 0.723, P less than 0.01), where y is MMF (unit; mg/l, uncorrected for urine density) in urine and x is DMF (ppm) in air, when only those exposed to DMF were selected, and the injection port temperature was set at 250 degrees C. From this equation, it was possible to estimate that about 10% of the DMF absorbed will be excreted into urine as the MMF precursor. The slope of the regression line was significantly smaller among those exposed to DMF and toluene in combination as compared with those with DMF exposure only.
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Affiliation(s)
- T Kawai
- Osaka Occupational Health Service Center, Japan Industrial Health and Safety Association
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23
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Slatter JG, Mutlib AE, Abbott FS. Biotransformation of aliphatic formamides: metabolites of (+-)-N-methyl-N-(1-methyl-3,3-diphenylpropyl) formamide in rats. BIOMEDICAL & ENVIRONMENTAL MASS SPECTROMETRY 1989; 18:690-701. [PMID: 2790257 DOI: 10.1002/bms.1200180908] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The in vivo biliary and urinary metabolites of (+-)-N-methyl-N-(1-methyl-3,3-diphenylpropyl) formamide (1) from male Wistar rats have been characterized by gas chromatography/mass spectrometry. In urine, non-conjugated metabolites included 1,1-diphenyl-3-butanone (4) and 3-methylamino-1,1,diphenylbutane (7). beta-Glucuronidase liberated 4, 1,1-diphenyl-3-butanol (5), 1,1-diphenyl-3-butanone oxime (6), N-hydroxymethyl-N-(1-methyl-3, 3-diphenylpropyl) formamide (3), 1-(4-hydroxyphenyl)-1-phenyl-3-butanone (11), 1-(4-hydroxyphenyl)-1-phenyl-3-butanone oxime (12), N-methyl-N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (8), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanone (16); 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanol (17), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanone oxime (18), N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (14) and N-methyl-N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (13). Most of the carbinolamide (3) decomposed in the gas chromatograph inlet to N-(1-methyl-3,3-diphenylpropyl) formamide (2) unless stabilized as a trimethylsilyl (TMS) derivative. In bile, compounds 1, 2, 3, 5, 6, 11, 12 and 16 were present as non-conjugated metabolites. beta-Glucuronidase also liberated N-(1-methyl-3-(4-hydroxyphenyl-3-phenylpropyl) formamide (9), and all of the previously listed compounds except 7. Trimethylsilylation of the conjugated bile fraction revealed the presence of an additional two compounds: N-hydroxymethyl-N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (10) and N-hydroxymethyl-N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl ) formamide (15). A stable carbinolamide metabolite standard was synthesized and the mass spectral fragmentations of its TMS derivative studied by tandem mass spectroscopy. This is the first report on stable carbinolamide metabolites of high-molecular-weight formamides.
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Affiliation(s)
- J G Slatter
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver
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Mráz J, Cross H, Gescher A, Threadgill MD, Flek J. Differences between rodents and humans in the metabolic toxification of N,N-dimethylformamide. Toxicol Appl Pharmacol 1989; 98:507-16. [PMID: 2718177 DOI: 10.1016/0041-008x(89)90179-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The widely used industrial solvent N,N-dimethylformamide (DMF) causes liver damage in occupationally exposed persons and is suspected of involvement in the generation of certain occupational malignancies. Here the extent of the biotransformation of DMF to three urinary metabolites has been compared in humans and rodents. The metabolites, which were quantified by gas chromatography (GC) are N-(hydroxymethyl)-N-methylformamide (HMMF), which yielded N-methylformamide on GC analysis, a species which decomposed to formamide on GC analysis, and N-acetyl-S-(N-methylcarbamoyl) cysteine (AMCC), measured after derivatization with ethanol to give ethyl N-methylcarbamate. Ten volunteers who absorbed between 28 and 60 mumol/kg DMF during an 8-hr exposure to DMF in the air at 60 mg/m3 excreted in the urine within 72 hr between 16.1 and 48.7% of the dose as HMMF, between 8.3 and 23.9% as formamide, and between 9.7 and 22.8% as AMCC. AMCC, together with HMMF, was also detected in the urine of workers after occupational exposure to DMF. The portion of the dose (0.1, 0.7, or 7.0 mmol/kg given ip) which was metabolized in mice, rats, or hamsters to HMMF varied between 8.4 and 47.3% of the dose; between 7.9 and 37.5% were excreted as formamide and only between 1.1 and 5.2%, as AMCC. The results suggest that there is a quantitative difference between the metabolic pathway of DMF to AMCC in humans and rodents. It is argued that the hepatotoxic potential of DMF may be linked to the extent of its metabolic conversion to AMCC.
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Affiliation(s)
- J Mráz
- Pharmaceutical Sciences Institute, Aston University, Birmingham, England
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Tulip K, Nicholson JK, Timbrell JA. A study of the metabolism of dimethylformamide in the rat by high resolution proton NMR spectroscopy. J Pharm Biomed Anal 1989; 7:499-505. [PMID: 2562322 DOI: 10.1016/0731-7085(89)80036-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- K Tulip
- Toxicology Unit, School of Pharmacy, London, UK
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Mráz J. Gas chromatographic method for the determination of N-acetyl-S-(N-methylcarbamoyl)cysteine, a metabolite of N,N-dimethylformamide and N-methylformamide, in human urine. JOURNAL OF CHROMATOGRAPHY 1988; 431:361-8. [PMID: 3243790 DOI: 10.1016/s0378-4347(00)83104-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A simple method has been developed for the determination of N-acetyl-S-(N-methylcarbamoyl)cysteine in human urine. Treatment of a urine sample (1 ml) with ethanol (2 ml) and potassium carbonate (1.5 g) produces ethyl N-methylcarbamate, which is extracted into ethanol and measured by packed column gas chromatography with nitrogen-sensitive detection. The limit of quantitation in human urine is 1 microgram/ml and the between-sample coefficient of variation is 5-11%. Simultaneously, N,N-dimethylformamide, N-methylformamide and formamide can also be determined.
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Affiliation(s)
- J Mráz
- Institute of Hygiene and Epidemiology, Prague, Czechoslovakia
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Mráz J, Turecek F. Identification of N-acetyl-S-(N-methylcarbamoyl)cysteine, a human metabolite of N,N-dimethylformamide and N-methylformamide. JOURNAL OF CHROMATOGRAPHY 1987; 414:399-404. [PMID: 3571407 DOI: 10.1016/0378-4347(87)80064-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Abstract
Scattered case reports of accidental exposure and a few epidemiological studies have indicated that the liver is the main target organ following acute and chronic exposure to dimethylformamide (DMF). This has been confirmed in several animal species. In humans, ethanol intolerance is one of the earliest manifestations of (excessive) exposure to DMF, followed at higher exposure levels by various complaints (nausea, vomiting, abdominal pain) and the release of liver cytolytic enzymes in the plasma. The metabolic pathway of DMF has been recently clarified, but the primary cellular lesion responsible for its hepatotoxicity is still unknown.
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Kestell P, Gill MH, Threadgill MD, Gescher A, Howarth OW, Curzon EH. Identification by proton NMR of N-(hydroxymethyl)-N-methylformamide as the major urinary metabolite of N,N-dimethylformamide in mice. Life Sci 1986; 38:719-24. [PMID: 3951328 DOI: 10.1016/0024-3205(86)90586-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Urine samples from mice which had received N,N-dimethylformamide were investigated by high field 1H-NMR spectroscopy. The most prominent signals in the N-CH3 region had chemical shifts identical with those of N,N-dimethylformamide (delta 2.85, 3.01) and N-(hydroxymethyl)-N-methylformamide (delta 2.91, 3.05). Resonances downfield of delta 7.5 (from formyl protons) also coincided with those of the reference formamides. When [14C]methyl-labelled N,N-dimethylformamide was injected and urine samples investigated by radio thin layer chromatography, the major area of radioactivity corresponded to the Rf of N-(hydroxymethyl)-N-methylformamide. Dimethylamine and methylamine were found to be minor metabolites of N,N-dimethylformamide.
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Kennedy GL. Biological effects of acetamide, formamide, and their monomethyl and dimethyl derivatives. Crit Rev Toxicol 1986; 17:129-82. [PMID: 3530639 DOI: 10.3109/10408448609023768] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The industrial use of certain acetamides and formamides (particularly DMAC and DMF) for their solvent properties has resulted in rather extensive examination of their biological properties. Both DMAC and DMF are rapidly absorbed through biological membranes and are metabolized by demethylation first to monomethyl derivatives and then to the parent acetamide or formamide. Relatively high single doses to various species following oral, dermal, i.p., i.v., or inhalation exposures generally are required to produce mortality. The liver is the primary target following acute high level exposure, but massive doses can also produce damage to other organs and tissues. Repeated sublethal treatment by various routes also shows the liver to be the target organ with the degree of damage being proportional to the amount absorbed. With MMF, the potential usefulness as a cancer chemotherapeutic agent needs to be measured against the hepatotoxic effects produced in man. Acetamides and formamides are generally inactive in mutagenicity tests. Mammalian test systems do not appear to be genetically sensitive and DMF has been recommended for use as the vehicle in microbial assays designed to test for genetic activity of hard-to-dissolve chemicals. Embryotoxicity can be demonstrated at high doses; doses which generally show toxicity to the maternal animals. Structural abnormalities in sensitive species such as the rabbit are produced following exposure at near-lethal levels. The spectrum of abnormalities seen is broad and fails to show any time or site specificity in terms of developing organs/organ systems. Inhalation exposures to DMAC and DMF at levels producing some maternal toxicity in rats have produced no teratogenic response and only slight evidence of embryotoxicity. Long-term feeding of relatively high levels of acetamide produces liver cancer in rats. DMAC and DMF appear to be noncarcinogenic. The environmental toxicity of these chemicals is low. Liver damage can be produced by overexposure to these chemicals in man. Airborne concentrations need to be controlled and care should be taken to avoid excessive liquid contact as the chemicals are absorbed through the skin. A relationship exists between the amount of DMAC or DMF absorbed and the amount of MMAC or MMF excreted in the urine so that biomonitoring of the urinary metabolites can indicate situations in which total exposures, both dermal and inhalation, are excessive. An interaction between DMF and ethanol occurs such that signs, including severe facial flushing, appear when DMF-exposed individuals consume alcoholic beverages.
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Scailteur V, Lauwerys R. In vivo and in vitro oxidative biotransformation of dimethylformamide in rat. Chem Biol Interact 1984; 50:327-37. [PMID: 6086163 DOI: 10.1016/0009-2797(84)90040-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In rats and in humans, dimethylformamide (DMF) is mainly metabolized into N-hydroxymethyl-N-methylformamide (DMF-OH). The in vitro oxidation of DMF by rat liver microsomes is decreased in the presence of catalase and superoxide dismutase. The radical scavengers, dimethylsulfoxide (DMSO), tertiary butyl alcohol (t-butanol), aminopyrine, hydroquinone and trichloroacetonitrile reduce the oxidation of DMF to DMF-OH in vitro and in vivo. Conversely, DMF inhibits the demethylation of DMSO, t-butanol and aminopyrine. The addition of iron-EDTA to the incubation system induces the production of N-methylformamide (NMF) from DMF. These results support the hypothesis that the metabolic pathway leading from DMF to DMF-OH and NMF involves hydroxyl radicals. Superoxide radical and hydrogen peroxide take part in the metabolic process. DMF is preferentially metabolized into DMF-OH. NMF appears mainly when the production of hydroxyl radicals is stimulated, the methyl group being recovered as formic acid.
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Whitby H, Gescher A, Levy L. An investigation of the mechanism of hepatotoxicity of the antitumour agent N-methylformamide in mice. Biochem Pharmacol 1984; 33:295-302. [PMID: 6704151 DOI: 10.1016/0006-2952(84)90488-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
N-Methylformamide (NMF) has been reported to cause liver damage in animals and man. This hepatotoxicity was characterized in BALB/c mice by the release of liver enzymes into the plasma and by histopathological examination of livers after single and repeated administration of NMF. Whereas plasma levels of sorbitol dehydrogenase were elevated dramatically 24 hr after 400 mg/kg given as a single dose, the glutathione content of the livers was not different from controls even after repeated administration. Liver damage was apparent on gross inspection and was defined as periacinar necrosis on histopathology. A dose of 100 mg/kg did not cause damage even after repeated injections on five consecutive days. The hypothesis that NMF is metabolized to a chemically reactive species was tested. Incubation of mouse hepatocytes with 7 mM NMF for 80 min produced a decrease in intracellular glutathione. Exposure of hepatocytes to NMF for 240 min led to the production of breakdown products of lipid peroxides at levels significantly above controls. However, incubation of microsomes or mitochondria with NMF and NADPH did not lead to raised levels of lipid peroxides. The effects described were specific to NMF as incubation of N,N-dimethylformamide, N-hydroxymethylformamide or formamide with hepatocytes did not result in glutathione depletion or increased lipid peroxidation. NMF undergoes extensive metabolism in vivo and the results indicate that NMF forms a chemically reactive metabolite, even though incubation of the drug with liver fractions or hepatocytes did not lead to metabolites at levels which were analytically identifiable.
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