Quantification of haemoglobin binding of 4,4′-methylenebis(2-chloroaniline)(MOCA) in rats

Sabbioni, Gabriele; Neumann, Hans‐Günter

doi:10.1007/bf01977626

Cited by 25 publications

(11 citation statements)

References 23 publications

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“…Adducts to albumin and Hb are the most frequently studied protein adduct biomarkers for the risk assessment of various toxins. , The binding preference to these two proteins largely depends on the distinct chemical properties of different reactive metabolites. Generally, the binding tendency to Hb is considered to be higher for most reactive metabolites. − This is partly due to the more nucleophilic sites in Hb, including free cysteines and N-terminal amino acids, available for Hb to bind with reactive metabolites compared to albumin. − However, reactive metabolites of some toxins, such as aflatoxin B1, naphthalene, and benzidine, have been demonstrated to mainly bind to albumin with relatively lower amounts of Hb adducts formed. ,, The different binding sites and membrane permeability of different reactive metabolites may contribute to the preference of their binding to Hb or albumin. Previously, our group has found that the levels of pyrrole–protein adducts in the Hb fraction were higher than that in the plasma fraction collected from rats treated with different dosages of riddelliine, another toxic PA .…”

Section: Discussionmentioning

confidence: 99%

Pyrrole–Hemoglobin Adducts, a More Feasible Potential Biomarker of Pyrrolizidine Alkaloid Exposure

Ruan

Chen

et al. 2019

Chem. Res. Toxicol.

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Pyrrolizidine alkaloids (PAs) are naturally occurring phytotoxins widely distributed in about 3% of flowering plants. The formation of PA-derived pyrrole–protein adducts is considered as a primary trigger initiating PA-induced hepatotoxicity. The present study aims to (i) further validate our previous established derivatization method using acidified ethanolic AgNO3 for the analysis of pyrrole–protein adducts and (ii) apply this method to characterize the binding tendency, dose–response, and elimination kinetics of pyrrole–protein adducts in blood samples. Two pyrrole–amino acid conjugates, (±)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP)–cysteine (7-cysteine-DHP) and 9-histidine-DHP, were synthesized and used to demonstrate that acidified ethanolic AgNO3 derivatization can cleave both S-linkage and N-linkage of pyrrole–protein adducts. Subsequently, using precolumn AgNO3 derivatization followed by ultra-high-pressure liquid chromatography/mass spectrometry analysis, we quantified pyrrole–protein adducts in monocrotaline-treated rat blood protein fractions, including hemoglobin (Hb), plasma, albumin, and plasma residual protein fractions, and found that the amount of pyrrole–Hb adducts was significantly higher than that in all plasma fractions. Moreover, elimination half-life of pyrrole–Hb adducts was also significantly longer than pyrrole–protein adducts in plasma fractions (12.08 vs 2.54–2.93 days). In addition, we also tested blood samples obtained from five PA-induced liver injury patients and found that the amount of pyrrole–protein adducts in blood cells was also remarkably higher than that in plasma. In conclusion, our findings for the first time confirmed that the AgNO3 derivatization method could be used to measure both S- and N-linked pyrrole–protein adducts and also suggested that pyrrole–Hb adducts with remarkably higher level and longer life span could be a better biomarker of PA exposure.

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Section: Discussionmentioning

confidence: 99%

Pyrrole–Hemoglobin Adducts, a More Feasible Potential Biomarker of Pyrrolizidine Alkaloid Exposure

Ruan

Chen

et al. 2019

Chem. Res. Toxicol.

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“…For some compounds such as aflatoxin B1, the carcinogenic metabolites bind preferentially to serum albumin (Sabbioni et al 1987). Sabbioni and Neumann (1990) were unable to hydrolyze 4,4-methylene bis(2-chloroaniline) off of albumin from rats sacrificed 24 h after treatment. However, it is presently unclear the utility of albumin adducts for biomonitoring studies.…”

Section: Discussionmentioning

confidence: 99%

Binding characteristics of ortho-toluidine to rat hemoglobin and albumin

DeBord¹,

Swearengin²,

Cheever³

et al. 1992

Arch Toxicol

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The binding characteristics of [14C]ortho-toluidine (OT), a suspect human carcinogen, were investigated in male Sprague-Dawley rats. Rats were administered [14C]OT i.p. at 10, 20, 40, 50, or 100 mg/kg body weight, then sacrificed at 2, 4, 8, 18, 24, 48, or 72 h, or 7, 14, or 28 days. Hemoglobin (Hb) and albumin (Alb) were isolated from blood, and OT binding was determined by liquid scintillation counting. For Alb, peak binding occurred at 50 mg/kg at the 4-h time point (15.6 ng OT/mg Alb), while for Hb peak binding was observed at 24 h at the 100 mg/kg dose (23.0 +/- 5.1 ng OT/mg Hb). OT-Alb binding was not linear; however, OT-Hb binding appeared to increase linearly in a dose-dependent manner. Biological half-lives of OT bound to Alb or Hb were observed to be 2.6 and 12.3 days, respectively, after rats were administered a single dose of [14C]OT and sacrificed after 4 h to 28 days. The effect of route of administration on OT-Hb adduct formation was investigated, and approximately a two-fold increase in radioactivity bound to Hb was observed after i.p. administration of 100 mg/kg [14C]OT versus oral intubation. Additional studies were carried out to investigate the effect of microsomal enzyme induction. An increase in OT-Hb binding was seen in rats pretreated with phenobarbital compared to rats pretreated with beta-naphthoflavone or without pretreatment; however, this increase was not statistically significant. These results suggest that OT-Hb and OT-Alb adduct formation may be a valuable biomarker for assessing workplace exposure.

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“…Measurements of MOCA adducts in rat Hb have been made by radiochemical (12), high-performance liquid chromatography (HPLC) with electrochemical detection (13), gas chromatography-mass spectrometry (GC-MS) (13), and by GC with electron capture detection (8). We report here on an improved GC-MS method, using a stable isotope-labeled internal standard, for the determination of MOCA Hb adducts and report on its application to binding studies in the rat.…”

Section: Introductionmentioning

confidence: 99%

Monitoring exposure to 4,4'-methylene-bis(2-chloroaniline) through the gas chromatography-mass spectrometry measurement of adducts to hemoglobin.

Bailey

Brooks

Farmer

et al. 1993

Environ Health Perspect

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4,4'-Methylene-bis(2-chloroaniline) (MOCA) is widely used as a curing agent in the plastics industry. The determination of the covalently bound reaction products to hemoglobin (Hb) has been investigated as a biomonitoring method for occupational exposure to this potential human carcinogen. Initial studies using the 14C-ring-labeled MOCA showed that 24 hr after a single IP dosage to rats (3.74 mumole/kg), 0.08% of the administered dose was adducted to the Hb, and base hydrolysis liberated 38% of the bound radioactivity. The only product released on hydrolysis was the parent diamine. A specific and sensitive assay procedure using capillary gas chromatography-mass spectrometry has been developed for determining the base-released MOCA adduct down to levels of 20 pmole/g Hb. This method has been used to establish a linear dose-response relationship in IP dosed rats between production of the adduct and dose of MOCA (3.74-44.94 mumole/kg). It is proposed to use analysis of the Hb adduct as a dosimeter for industrial workers exposed to MOCA.

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Quantification of haemoglobin binding of 4,4′-methylenebis(2-chloroaniline)(MOCA) in rats

Cited by 25 publications

References 23 publications

Pyrrole–Hemoglobin Adducts, a More Feasible Potential Biomarker of Pyrrolizidine Alkaloid Exposure

Pyrrole–Hemoglobin Adducts, a More Feasible Potential Biomarker of Pyrrolizidine Alkaloid Exposure

Binding characteristics of ortho-toluidine to rat hemoglobin and albumin

Monitoring exposure to 4,4'-methylene-bis(2-chloroaniline) through the gas chromatography-mass spectrometry measurement of adducts to hemoglobin.

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