Characterization of a Phospholipid Adduct Formed in Sprague Dawley Rats by Chloroform Metabolism: NMR Studies

Guastadisegni, Cecilia; Guidoni, Laura; Balduzzi, Maria; Viti, Vincenza; Consiglio, Emma Di; Vittozzi, Luciano

doi:10.1002/(sici)1099-0461(1998)12:2<93::aid-jbt4>3.0.co;2-j

Cited by 13 publications

(6 citation statements)

References 31 publications

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“…Lipids are not usually thought of as targets for electrophilic metabolites, although several precedents involving the amine group of PE phospholipids exist. For example phosgene, formed by oxidative metabolism of chloroform, forms lipid adducts by cross-linking two molecules of PE through their amine groups in a urea linkage. Similarly, the oxidative metabolite of halothane trifluoroacetylates the amine group of PE lipids, while the reactive metabolite generated by the action of cysteine conjugate β-lyase on S -(1,1,2,2-tetrafluoroethyl)- l -cysteine generates difluorothioacetyl-PE adducts and, as noted above, the S,S -dioxide metabolite of thiobenzamide benzimidoylates the amine group of PE lipids in microsomal membranes …”

Section: Discussionmentioning

confidence: 99%

Covalent Modification of Lipids and Proteins in Rat Hepatocytes and in Vitro by Thioacetamide Metabolites

Sarma

Hajovsky

Koen

et al. 2012

Chem. Res. Toxicol.

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Thioacetamide (TA) is a well-known hepatotoxin in rats. Acute doses cause centrilobular necrosis and hyperbilirubinemia while chronic administration leads to biliary hyperplasia and cholangiocarcinoma. Its acute toxicity requires its oxidation to a stable S-oxide (TASO) that is oxidized further to a highly reactive S,S-dioxide (TASO2). To explore possible parallels between the metabolism, covalent binding and toxicity of TA and thiobenzamide (TB) we exposed freshly isolated rat hepatocytes to [14C]-TASO or [13C2D3]-TASO. TLC analysis of the cellular lipids showed a single major spot of radioactivity that mass spectral analysis showed to consist of N-acetimidoyl PE lipids having the same side chain composition as the PE fraction from untreated cells; no carbons or hydrogens from TASO were incorporated into the fatty acyl chains. Many cellular proteins contained N-acetyl- or N-acetimidoyl lysine residues in a 3:1 ratio (details to be reported separately). We also oxidized TASO with hydrogen peroxide in the presence of dipalmitoyl phosphatidylenthanolamine (DPPE) or lysozyme. Lysozyme was covalently modified at five of its six lysine side chains; only acetamide-type adducts were formed. DPPE in liposomes also gave only amide-type adducts, even when the reaction was carried out in tetrahydrofuran with only 10% water added. The exclusive formation of N-acetimidoyl PE in hepatocytes means that the concentration or activity of water must be extremely low in the region where TASO2 is formed, whereas at least some of the TASO2 can hydrolyze to acetylsulfinic acid before it reacts with cellular proteins. The requirement for two sequential oxidations to produce a reactive metabolite is unusual, but it is even more unusual that a reactive metabolite would react with water to form a new compound that retains a high degree of chemical reactivity toward biological nucleophiles. The possible contribution of lipid modification to the hepatotoxicity of TA/TASO remains to be determined.

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Section: Discussionmentioning

confidence: 99%

Covalent Modification of Lipids and Proteins in Rat Hepatocytes and in Vitro by Thioacetamide Metabolites

Sarma

Hajovsky

Koen

et al. 2012

Chem. Res. Toxicol.

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“…Binding to glutathione has also been observed (10). Recently, binding of phosgene, generated by chloroform metabolism, to phospholipids in liver mitochondria was reported (11). Pereira and Chang (12) observed binding of radioactivity to hemoglobin upon administration of [ 14 C]chloroform to rats.…”

Section: Introductionmentioning

confidence: 99%

In Vitro Adduct Formation of Phosgene with Albumin and Hemoglobin in Human Blood

Noort¹,

Hulst²,

Fidder³

et al. 2000

Chem. Res. Toxicol.

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The development of procedures for retrospective detection and quantitation of exposure to phosgene, based on adducts to hemoglobin and albumin, is described. Upon incubation of human blood with [(14)C]phosgene (0-750 microM), a significant part of radioactivity (0-13%) became associated with globin and albumin. Upon Pronase digestion of globin, one of the adducts was identified as the pentapeptide O=C-(V-L)-S-P-A, representing amino acid residues 1-5 of alpha-globin, with a hydantoin function between N-terminal valine and leucine. Micro-LC/tandem MS analyses of tryptic as well as V8 protease digests identified one of the adducts to albumin as a urea resulting from intramolecular bridging of lysine residues 195 and 199. The adducted tryptic fragment could be sensitively analyzed by means of micro-LC/tandem MS with multiple-reaction monitoring (MRM), enabling the detection in human blood of an in vitro exposure level of >/=1 microM phosgene.

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“…At low concentrations, phosgene mainly reacts with alveolar surfactant, a mixture of lipids and proteins whose function is to lower surface tension and prevent atelectasis. Phosgene has been shown to form adducts with phosphotidylcholine (PC), the main lipid constituent of surfactant [29]. As a result, the structure and function of both PC and surfactant are altered.…”

Section: 0 Results and Discussionmentioning

confidence: 99%

Conceptual approaches for treatment of phosgene inhalation-induced lung injury

Holmes¹,

Keyser²,

Paradiso³

et al. 2016

Toxicology Letters

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Toxic industrial chemicals are used throughout the world to produce everyday products such as household and commercial cleaners, disinfectants, pesticides, pharmaceuticals, plastics, paper, and fertilizers. These chemicals are produced, stored, and transported in large quantities, which poses a threat to the local civilian population in cases of accidental or intentional release. Several of these chemicals have no known medical countermeasures for their toxic effects. Phosgene is a highly toxic industrial chemical which was used as a chemical warfare agent in WWI. Exposure to phosgene causes latent, non-cardiogenic pulmonary edema which can result in respiratory failure and death. The mechanisms of phosgene-induced pulmonary injury are not fully identified, and currently there is no efficacious countermeasure. Here, we provide a proposed mechanism of phosgene-induced lung injury based on the literature and from studies conducted in our lab, as well as provide results from studies designed to evaluate survival efficacy of potential therapies following whole-body phosgene exposure in mice. Several therapies were able to significantly increase 24 hr survival following an LCt50–70 exposure to phosgene; however, no treatment was able to fully protect against phosgene-induced mortality. These studies provide evidence that mortality following phosgene toxicity can be mitigated by neuro- and calcium-regulators, antioxidants, phosphodiesterase and endothelin receptor antagonists, angiotensin converting enzymes, and transient receptor potential cation channel inhibitors. However, because the mechanism of phosgene toxicity is multifaceted, we conclude that a single therapeutic is unlikely to be sufficient to ameliorate the multitude of direct and secondary toxic effects caused by phosgene inhalation.

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Characterization of a Phospholipid Adduct Formed in Sprague Dawley Rats by Chloroform Metabolism: NMR Studies

Cited by 13 publications

References 31 publications

Covalent Modification of Lipids and Proteins in Rat Hepatocytes and in Vitro by Thioacetamide Metabolites

Covalent Modification of Lipids and Proteins in Rat Hepatocytes and in Vitro by Thioacetamide Metabolites

In Vitro Adduct Formation of Phosgene with Albumin and Hemoglobin in Human Blood

Conceptual approaches for treatment of phosgene inhalation-induced lung injury

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