Comutagenic Action of Norharman and Harman

Nagao, Minako; Yahagi, Takie; Kawachi, Takashi; Sügimura, Takashi; Kosuge, Takuo; Tsuji, Kiichiro; Wakabayashi, Keiji; Mizusaki, Shigenobu; Matsumoto, Takashi

doi:10.2183/pjab1945.53.95

Cited by 57 publications

(26 citation statements)

References 5 publications

(1 reference statement)

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“…Consistent with previous reports (19,30), compounds I.and 2 were found to be potent mutagens ( Table 1). The mutagenic activity obtained with strain TM677 was much greater than the activities associated with compounds such as benzo[a Ipyrene or 2-acetamidofluorene and was comparable to the activity of aflatoxin B1.…”

Section: Resultssupporting

confidence: 92%

“…The intense mutagenicity and cytotoxicity of certain 3-amino-l-methyl-5H-pyrido [4,3-b]indoles in bacterial and mammalian (33) assays and the implications of their possible occurrence as dietary constituents (19,30) prompted us to investigate the mechanism(s) by which they exert their mutagenic effects. Although the compounds of interest bear an obvious structural relationship to those in the 2-aminofluorene series, the much greater mutagenic activity of the indole derivatives suggested that the mechanism(s) by which they are activated metabolically and react with DNA might not parallel the pathways utilized by the aminofluorenes.…”

Section: Discussionmentioning

confidence: 99%

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There is a correlation between the DNA affinity and mutagenicity of several 3-amino-1-methyl-5H-pyrido[4,3-b]indoles.

Pezzuto

Lau

Luh

et al. 1980

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

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3 -Amino -1 -methyl -5H -pyrido[4,3 -blindole, previously reported to be a component of tryptophan pyrolysates, is an intensely mutagenic compound requiring microsomal activation for expression of mutagenicity. We have found that this species and several synthetic analogs interact noncovalently with calf thymus DNA, as judged by both fluorescence quenching and differential dialysis. Remarkably, this noncovalent interaction correlated with the mutagenic potential of the compounds in a bacterial mutagenesis assay. Therefore, it is suggested that the mechanism of mutagenesis involves metabolic activation followed by physicochemical interaction with DNA; for these compounds, the latter step may be limiting for the expression of mutagenicity.Carcinogenic chemicals produced by incomplete combustion processes represent a significant hazard to which we are exposed. The molecular mechanism(s) by which these chemicals initiate and promote the development of tumors has not been elucidated despite many years of intensive investigation, although it is now generally accepted that covalent reactions with critical cellular target molecules play an integral role in the process. Many carcinogens require metabolic activation prior to adduct formation (1, 2); due largely to the work of Miller and Miller (2,3) it is known that the activated species are electrophilic in nature. It has become increasingly clear that carcinogenic chemicals can generally also behave as mutagens (4), supporting the concept of somatic mutation as the basis of carcinogenesis (4-6).An active, and somewhat controversial, area of investigation has involved the correlation of the carcinogenic or mutagenic potential of several chemicals with their relative affinities for nucleic acids. For example, Brookes and Lawley (7) mutagen structurally reminiscent of 2-aminofluorene and reported to be identical with a product resulting from pyrolysis of tryptophan (19). In the present study, compound 1, and several synthetic analogs thereof, have been shown to be mutagenic toward Salmonella typhimurium only in the presence of a microsomal activating system. Remarkably, for these compounds there is a reasonable correlation between mutagenic activity and the extent of physicochemical interaction with calf thymus DNA. Discussed herein is the nature of this correlation and its possible implications for the mechanism of action of these species as mutagens.MATERIALS AND METHODS Synthesis of Test Substances. The syntheses of compounds 1 and 2 have been reported (20, 21). As will be described in detail elsewhere, compound 3 was prepared from 1 (acetic anhydride, pyridine, 25°C) as a white solid in high yield and then converted to 3-ethylamino-1-methyl-5H-pyrido[4,3-b]indole (4) by treatment with lithium aluminum hydride in tetrahydrofuran; both were characterized by UV, NMR, and mass spectrometry. Analogous acetylation of 4 and reductive treatment of the formed acetate afforded 3-(N,N-diethylamino)-1-methyl-5H-pyrido [4,3-b]indole (5). Deamination of I was effected by...

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Section: Resultssupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

There is a correlation between the DNA affinity and mutagenicity of several 3-amino-1-methyl-5H-pyrido[4,3-b]indoles.

Pezzuto

Lau

Luh

et al. 1980

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

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“…1(f), and serves to underline the variability in in vitro test response to be expected with changes in the S-9 mix or overall in vitro metabolism (Ashby and Styles 1 978a, b). These effects closely parallel those produced by norharman with DAB in the Ames assay (Nagao et al, 1977) and those produced by 4'ethylation of DAB, to be discussed later. These observations may also cast some light on the fact that most derivatives of DAB carrying a substituent ortho to the azo bridge are non-carcinogenic (reviewed by Arcos and Argus, 1974).…”

Section: Discussionsupporting

confidence: 57%

“…Whilst DAB can produce a positive effect in the Ames assay, this response cannot be relied upon (Ames et al, 1973;McCann et al, 1975;Purchase et al, 1978;Ashby and Purchase, 1977;Nagao et al, 1977). Such uncertainty is important in a study such as the present one.…”

mentioning

confidence: 83%

In vitro evaluation of some derivatives of the carcinogen butter yellow: implications for environmental screening

Ashby¹,

Styles²,

Paton³

1978

Br J Cancer

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Summary. The rat-liver carcinogen 4-dimethylaminoazobenzene (Butter Yellow, DAB) and 12 of its structural analogues have been evaluated in a cell transformation assay. Eight of these analogues have already been tested for carcinogenicity in rats, whilst the remaining 4 are new or hitherto untested. Benzidine and its 3,3' -disulphonic acid derivative have also been evaluated.The in vitro results agree with long-term animal data for 8 compounds but disagree in finding DAB-4'-sulphonic acid, 4-trifluoromethyl-DAB and 4-diethylaminoazobenzene positive. Possible reasons for these divergencies are discussed. It is concluded that 9-phenylazojulolidine and N-methyl-5-phenylazoindoline have carcinogenic potential and that 3,5-dimethyl-4-aminoazobenzene and 4-aminoazobenzene-4'-sulphonic acid are likely to prove non-carcinogenic.Addition of azobenzene to the in vitro assay medium increases the transforming potency of DAB 25-fold. It is suggested that it acts as a competitive substrate for one of the enzymes that detoxify DAB, and that this effect is related to that produced by norharman.Sulphonic-acid derivatives of established carcinogens are usually inactive. The basis of this effect has been investigated, and it is suggested that it can operate by two separate mechanisms.It has been established that this assay cannot be relied upon to predict the in vivo potency of a carcinogen. Consideration has been given to possible changes which could be made to the liver activation system (the S -9 mix) currently used in in vitro carcinogenicity assays, and a diagram is presented of the metabolic conversions of a comzpound which might lead to mutation or tumour formation. This enables the term potential carcinogen to be accurately defined, and indicates a possible difference between absolute non-carcinogens and compounds which fail to produce cancer in vivo.

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“…Their mutagenicities in the Salmonella test system were greatly increased by norharman and harman, which were also found in tryptophan pyrolysate (2). Because norharman and harman themselves have no mutagenic activity, they were called "comutagens."…”

mentioning

confidence: 99%

Comutagenic effect of norharman and harman with 2-acetylaminofluorene derivatives.

Umezawa¹,

Shirai²,

Matsushima³

et al. 1978

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

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ABSTRACr Norharman enhanced the known mutagenicity of 2-acetylaminofluorene derivatives in the Salmonella test system. The mutagenicities of 2-acetylaminofluorene, 2-aminofluorene, and N-hydroxy-2-acetylaminofluorene were enhanced by norharman only when rat liver microsomal enzymes were added, whereas the mutagenicity of N-acetoxy--acetylaminofluorene was increased in the absence of microsomal enzymes. Harman also increased mutagenesis, although less so than norharman.Two highly mutagenic compounds isolated from tryptophan pyrolysate have been found to be -y-carbolinies (1). Their mutagenicities in the Salmonella test system were greatly increased by norharman and harman, which were also found in tryptophan pyrolysate (2). Because norharman and harman themselves have no mutagenic activity, they were called "comutagens." Later it was reported that norharman enhanced the mutagenicity of benzo[a]pyrene and dimethylaminoazobenzene and that aniline or o-toluidine, either of which alone is nonmutagenic, became mutagenic under the comutagenic action of norharman (2, 3). All the mutagens so far found to be activated by norharman required metabolic activation by S-9 mix.2-Acetylaminofluorene and many of its derivatives are both potent mutagens and carcinogens (4). Among these compounds, 2-acetylaminofluorene(AAF) and 2-aminofluorene(AF) require metabolic activation for mutagenesis, but N-hydroxy-AAF and N-acetoxy-AAF can induce mutagenesis without metabolic activation (5).This paper reports that the mutagenicities of AAF derivatives were enhanced by norharman and harman in the mutation test using his-Salmonella typhimurium and considers the mechanism of the comutagenic effect. Mutation Assay. Mutation tests were carried out by a slight modification of the method described by Ames et al. (6). Mutagens were dissolved in 0.025 ml of dimethyl sulfoxide and added to 0.5 ml of S-9 mix (S-9 mix was prepared from the post-mitochondrial supernatant of the liver of rats that had been pretreated with polychlorinated biphenyl; our S-9 mix contained 4 ,gmol of NADH and NADPH per ml but no NADP) or 0.2 M sodium phosphate buffer (pH 7.4) with 0.1 ml of bacterial suspension. Norharman and harman were dissolved in 0.02 ml of dimethyl sulfoxide and added at the same time as the mutagens. The mixtures were incubated for 30 min at 30°with shaking. Then they were rapidly mixed with 2 ml of molten soft agar containing 0.1 Mmol of L-histidine and biotin, poured onto minimal glucose agar plates, and incubated for 2 days at 370. MATERIALS AND METHODS Chemicals RESULTSIn the presence of S-9 mix for metabolic activation, 0.02 ,umol of AAF reverted approximately 1000 colonies from a lawn of 108 S. typhimurium TA98 organisms in our test system. Addition of 1 ,mol of norharman enhanced this mutagenesis about 6-fold (Fig. 1A). Harman increased the mutagenicity of AAF about 3fold. Similarly, 0.02 jmol of AF reverted approximately 1000 colonies with S-9 mix, and norharman and harman showed comutagenic effects with AF (Fig. 1B).The dose-response curves f...

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Comutagenic Action of Norharman and Harman

Abstract: No. 2] Proc. Japan Acad., 53 (1977) 95 26. Comutagenic Action o f Norharman and Harman

Cited by 57 publications

References 5 publications

There is a correlation between the DNA affinity and mutagenicity of several 3-amino-1-methyl-5H-pyrido[4,3-b]indoles.

There is a correlation between the DNA affinity and mutagenicity of several 3-amino-1-methyl-5H-pyrido[4,3-b]indoles.

In vitro evaluation of some derivatives of the carcinogen butter yellow: implications for environmental screening

Comutagenic effect of norharman and harman with 2-acetylaminofluorene derivatives.

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