Determination of Benzidine,N-Acetylbenzidine, andN,N′-Diacetylbenzidine in Human Urine by Capillary Gas Chromatography/Negative Ion Chemical Ionization Mass Spectrometry

Hsu, Fong‐Fu; Lakshmi, Vijaya M.; Rothman, Nat; Bhatnager, V. K.; Hayes, Richard B.; Kashyap, Rekha; Parikh, D J; Kashyap, S. K.; Turk, John; Zenser, Terry V.; Davis, Brett M.

doi:10.1006/abio.1996.0070

Cited by 31 publications

(17 citation statements)

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“…In contrast, for diamines such as benzidine, N-acetylation does not compete and in fact most likely enhances oxidation of the second amine, thereby increasing risk in human NAT2 rapid acetylators (Carreon et al, 2006). Workers exposed to benzidine show relatively high levels of N-acetylbenzidine in the urine but virtually no N,NЈ-diacetylbenzidine (Hsu et al, 1996;Rothman et al, 1996). DNA adducts derive from N-acetylbenzidine in the rat (Kennelly et al, 1984) and humans , suggesting that N-acetylation is an activation pathway for benzidine.…”

Section: Discussionmentioning

confidence: 99%

4,4′-Methylenedianiline-Induced Hepatotoxicity Is Modified by N-Acetyltransferase 2 (NAT2) Acetylator Polymorphism in the Rat

Zhang

Lambert²,

Doll³

et al. 2005

J Pharmacol Exp Ther

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4,4Ј-Methylenedianiline (MDA) is widely used in the manufacturing of polyurethane foam, epoxy resins, and polymers. Exposure to MDA induces liver damage in humans and rats. MDA undergoes N-acetylation catalyzed by N-acetyltransferase 1 (NAT1) and 2 (NAT2) in the liver. Both human and rat NAT2 are polymorphic, and human NAT2 genetic polymorphism modifies the frequency and/or severity of drug and xenobiotic toxicity in human populations. Recombinant expression of rat Nats in Escherichia coli showed that MDA was acetylated by both recombinant rat Nat1 and Nat2 and was catalyzed at substantially higher rates by rapid acetylator Nat2 compared with slow acetylator Nat2. Rapid acetylator F344 rat liver cytosols catalyzed the N-acetylation of MDA at significantly higher rates than those from slow acetylator Wistar-Kyoto (WKY) inbred rats. To test the effect of NAT2 genetic polymorphism on hepatotoxicity from acute MDA exposure, we compared hepatotoxicity in rapid (F344) and slow (WKY) Nat2 acetylator inbred rats that were administered MDA. Based on the results of dose-response studies ranging up to 150 mg/kg MDA administered by intragastric gavage, the effect of a moderately hepatotoxic dose (37.5 mg/kg) was compared in rapid versus slow acetylator rats. Plasma alanine transaminase enzyme activities were approximately 5-fold higher (p Ͻ 0.05) in rapid versus slow acetylator rats after MDA treatment, and necrotizing hepatitis with portal damage consisting of bile ductular necrosis, portal expansion, and inflammation was clearly more prominent. These results suggest that acetylator phenotype is an important factor for susceptibility toward MDA hepatotoxicity.

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Section: Discussionmentioning

confidence: 99%

4,4′-Methylenedianiline-Induced Hepatotoxicity Is Modified by N-Acetyltransferase 2 (NAT2) Acetylator Polymorphism in the Rat

Zhang

Lambert²,

Doll³

et al. 2005

J Pharmacol Exp Ther

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“…Post-workshift urine samples were analyzed at the Veterans Affairs Medical Center in St. Louis for BZ, N-acetylbenzidine (ABZ), and N,N'-diacetylbenzidine (DBZ) by capillary gas chromatography/negative chemical ion mass spectrometry as described (28).…”

Section: Methodsmentioning

confidence: 99%

The impact of interindividual variation in NAT2 activity on benzidine urinary metabolites and urothelial DNA adducts in exposed workers.

Rothman

Bhatnagar

Hayes

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

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Several epidemiologic studies indicate that NAT2-related slow N-acetylation increases bladder cancer risk among workers exposed to aromatic amines, presumably because N-acetylation is important for the detoxification of these compounds. Previously, we showed that NAT2 polymorphisms did not influence bladder cancer risk among Chinese workers exposed exclusively to benzidine (BZ), suggesting that NAT2 N-acetylation is not a critical detoxifying pathway for this aromatic amine. To evaluate the biologic plausibility of this finding, we carried out a cross-sectional study of 33 workers exposed to BZ and 15 unexposed controls in Ahmedabad, India, to evaluate the presence of BZ-related DNA adducts in exfoliated urothelial cells, the excretion pattern of BZ metabolites, and the impact of NAT2 activity on these outcomes. Four DNA adducts were significantly elevated in exposed workers compared to controls; of these, the predominant adduct cochromatographed with a synthetic N-(3'-phosphodeoxyguanosin-8-yl)-N'-acetylbenzidine standard and was the only adduct that was significantly associated with total BZ urinary metabolites (r = 0.68, P < 0.0001). To our knowledge this is the first report to show that BZ forms DNA adducts in exfoliated urothelial cells of exposed humans and that the predominant adduct formed is N-acetylated, supporting the concept that monofunctional acetylation is an activation, rather than a detoxification, step for BZ. However, because almost all BZ-related metabolites measured in the urine of exposed workers were acetylated among slow, as well as rapid, acetylators (mean ± SD 95 ± 1.9o vs. 97 + 1.6%, respectively) and NAT2 activity did not affect the levels of any DNA adduct measured, it is unlikely that interindividual variation in NAT2 function is relevant for BZ-associated bladder carcinogenesis.Aromatic amines must be metabolized within the host in order to exert mutagenic or carcinogenic activity (1). For many aromatic monoamines, including those found in tobacco smoke such as 4-aminobiphenyl (4-ABP) and 2-naphthylamine, N-acetylation appears to be a detoxification pathway, with the acetylated metabolite being excreted into the urine before it can be N-oxidized to a reactive form (2). In contrast, acetylation may be an activation pathway for benzidine (BZ), an aromatic diamine, in that N-acetylation of one amine group has been shown to facilitate N-oxidation to a reactive species by cytochrome P-450 (3, 4). Alternatively, BZ may be directly activated by prostaglandin-H synthetase in the bladder to benzidinediimine (the two-electron oxidation product), which can bind to DNA (5, 6). Thus, for BZ, the impact of acetylation on the production of the critical activated metabolite(s) is less certain and may be more complicated than for aromatic monoamines.The capacity to N-acetylate is polymorphic in humans (2); slow acetylators are homozygotic for a mutated N-acetyltransferase gene (NA72) that is generally responsible for decreased activity (7,8). In 1979, Lower et al. (9) proposed that individu...

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“…CYP 1A1 and 1A2 are the enzymes that are involved in Nhydroxylation of BZ. These enzymes are inhibited by α-naphthoflavone, ellipticine 50) , furafylline 52,53) , and 6-methyl-1,3,8-trichlorodibenzofuran 54) and induced by β-naphthoflavone 55,56) , 2,3,7,8-tetrachlorodibenzo-p-dioxine 54) , and triethylphosphorothioate 57) .…”

Section: Discussionmentioning

confidence: 99%

Effects of Ethanol and Phenobarbital on Hemoglobin Adducts Formation in Rats Exposed to Benzidine and Direct Black 38

et al. 2009

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Determination of Benzidine,N-Acetylbenzidine, andN,N′-Diacetylbenzidine in Human Urine by Capillary Gas Chromatography/Negative Ion Chemical Ionization Mass Spectrometry

Cited by 31 publications

References 0 publications

4,4′-Methylenedianiline-Induced Hepatotoxicity Is Modified by N-Acetyltransferase 2 (NAT2) Acetylator Polymorphism in the Rat

4,4′-Methylenedianiline-Induced Hepatotoxicity Is Modified by N-Acetyltransferase 2 (NAT2) Acetylator Polymorphism in the Rat

The impact of interindividual variation in NAT2 activity on benzidine urinary metabolites and urothelial DNA adducts in exposed workers.

Effects of Ethanol and Phenobarbital on Hemoglobin Adducts Formation in Rats Exposed to Benzidine and Direct Black 38

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