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J F Stavenuiter

Publications and source records attributed to J F Stavenuiter.

10 recordsLinked to original sources
PubMed1995

Chemical properties of the ultimate metabolites of 2-amino-5-phenylpyridine (PHE-P-1) and its ortho-methyl derivative.

The reactivity of the N-acetoxy metabolite of 2-amino-5-phenylpyridine (Phe-P-1), a pyrolysis product of phenylalanine, towards 2'-deoxyguanosine (dG), 2'-deoxyguanosine-3'-monophosphate (dGMP) and DNA was studied and compared with that of the ortho-methyl derivative. Reaction of 2-acetoxyamino-5-phenylpyridine (N-OAc-APP) with dG resulted in substitution at the 8-position of this nucleoside by the ortho carbon of the amine. The major reaction, however, was acetylation of dG. In contrast, 2-acetoxyamino-3-methyl-5-phenyl-pyridine (N-OAc-MeAPP) mainly attacked the 8-position of dG by the exocyclic nitrogen and hardly any acetylation of the nucleoside occurred. The adducts were chromatographically isolated and characterized by their mass and NMR spectra. Upon reaction of N-acetoxy compounds with DNA and dGMP, formation of the same adducts was observed, besides the formation of minor amounts of unidentified compounds, as was established by 32P-postlabelling analysis. The amount of DNA-bound amine, formed by the interaction of N-OAc-APP with DNA, was approximately 15 times smaller than that observed after the reaction with the corresponding ortho-methyl derivative under the same conditions.

Aminopyridines↗
PubMed1994

Sulfation of aromatic hydroxamic acids and hydroxylamines by multiple forms of human liver sulfotransferases.

Sulfation activity towards various heterocyclic and homocyclic aromatic hydroxamic acids and hydroxylamines was determined in adult human liver cytosol and with partially purified human liver sulfotransferases (STs). In adult human liver cytosols comparable ST activities towards N-hydroxy-2-acetyl-amino-5-phenylpyridine (N-OH-2AAPP), N-hydroxy-4-acetylaminobiphenyl (N-OH-4AABP) and N-hydroxy-4'fluoro-4-acetylaminobiphenyl (N-OH-4FAABP) were found, while the sulfation rates towards N-hydroxy-2-acetylaminofluorene (N-OH-2AAF), N-hydroxy-2-acetylaminonaphthalene (N-OH-2AAN), N-hydroxy-2-acetylaminophenanthrene (N-OH-2AAP) and N-hydroxy-4-acetylaminostilbene (N-OH-4AAS) were two- to five-fold lower. In adult liver cytosol ST activity was found towards all hydroxylamines tested. No significant differences were found for the various hydroxylamines. In general, the ST activities towards the various hydroxamic acids and hydroxylamines were comparable to phenol ST activity using adult liver cytosols. Partial purification of adult human liver STs was achieved by DEAE-Sepharose chromatography followed by anion exchange FPLC. Two separated protein peaks showing both N-OH-2AAPP and N-OH-2APP ST activities were observed and were designated human hydroxylamine/hydroxamic acid sulfotransferase (hHST) 1 and 2. Immunoblot analysis using an anti-rat estrogen ST antibody demonstrated cross reactivity with both hHSTs at a subunit mol. wt of 32 kDa corresponding to the phenol-sulfating form of phenol ST (P-PST). ST activity towards dopamine was low with both hHSTs, but hHST1 also contained significant capacity to sulfate dehydroepiandrosterone. The highest ST activity towards N-OH-2AAPP and N-OH-2APP was measured at pH 5.5 with both hHSTs. The Km values of the two hHSTs for sulfation of N-OH-2AAPP and N-OH-2APP were comparable, while the Vmax values for sulfation of N-OH-2APP were higher than for N-OH-2AAP with both hHSTs. FPLC anion exchange analysis of human platelet STs demonstrated that sulfation of N-OH-4ABP and N-OH-4AABP was associated with P-PST rather than M-PST (platelets do not possess any significant DHEA ST activity). Our results show that the various hydroxamic acids and hydroxylamines are converted by at least two hHSTs. The results presented here for the human liver hydroxamic acid and hydroxylamine ST activities are discussed in relation to those observed in the rat.

Adult↗
PubMed1993

Method for the analysis of oxidized nucleosides by gas chromatography/mass spectrometry.

A method for sensitive analysis of the oxidatively modified nucleosides 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 5-hydroxymethyl-2'-deoxyuridine (HMdU) is described. The method combines acetylation and pentafluorobenzylation of the nucleosides followed by analysis by gas chromatography/electron capture negative ion chemical ionization-mass spectrometry. The detection limits of the method for aqueous standards of HMdU and 8-OHdG were 12 and 18 fmol of starting material (signal-to-noise ratio, 3:1), respectively. The method was linear for 8-hydroxy-2'-deoxyguanosine over five orders of magnitude and gave satisfactory reproducibilities (intraassay RSD < or = 5%) for the analysis of 8-OHdG in both aqueous standards and urine fortified at the level of 35 nM. The limit of detection for the analysis of 8-OHdG in urine was 1.8 pmol, corresponding to a level of 8-OHdG in urine of 35 nM (10 micrograms/liter) at a urine sample volume of 50 microliters. Besides urine the method was applied to the analysis of 5-hydroxy-methyl-2'-deoxyuridine isolated from genomic DNA of Bacillus subtilis bacteriophage H1. Results obtained indicate that the method is potentially suitable for the determination of oxidized nucleosides in biological samples. The selectivity of the method should be enhanced in order to lower the limit of detection in biological samples.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1990

Synthesis of 13C-labeled steroid hormones.

The synthesis of 13C-labeled steroid hormones is reviewed. Two general approaches are highlighted: partial synthesis in which part of the steroid nucleus is replaced with 13C-labeled synthons, and total synthesis. Examples from both approaches, leading to (3-(3)C)-, (4-(13)C)-, (3,4-(13)C2)-, and (1,2,3,4-(13)C4)- labeled steroid hormones (e.g., testosterone, estradiol, progesterone, and cortisol), are presented.

Carbon Isotopes↗
PubMed1989

Synthesis of heterocyclic N-acetoxyarylamines and their reactivity with DNA.

2-Acetoxyamino-5-phenylpyridine and 2-acetoxyamino-3-methyl-5-phenylpyridine, being proposed ultimate carcinogens of the heterocyclic aromatic amines 2-amino-5-phenylpyridine (APP) and 2-amino-3-methyl-5-phenylpyridine (AMPP), respectively, were synthesized, crystallized and characterized. Using the 32P-postlabelling technique, we show that the total amount of adducts found in DNA after reaction with these N-acetoxyarylamines is at least 30- and 450-fold higher than in DNA reacted with equimolar amounts of the proposed proximate carcinogens 2-hydroxyamino-5-phenylpyridine and 2-hydroxyamino-3-methyl-5-phenylpyridine, respectively. These results support a postulated activation mechanism, in which N-acetoxyarylamines are the ultimate reactive species responsible for DNA modification by carcinogenic aromatic amines in vivo. The possibility to obtain the reactive 0-acetyl derivatives of APP and AMPP in crystalline form makes them unique model compounds for studies on the interaction of ultimate carcinogens of aromatic amines with DNA.

Amines↗
PubMed1988

Comparative carcinogenicity of the food pyrolysis product, 2-amino-5-phenylpyridine, and the known human carcinogen, 4-aminobiphenyl, in the neonatal B6C3F1 mouse.

2-Amino-5-phenylpyridine (2-APP) is a mutagenic heterocyclic aromatic amine that is formed by pyrolysis of phenylalanine in proteins. Since this mutagen is structurally similar to the multipotent carcinogen, 4-aminobiphenyl (4-ABP), we compared their relative tumorigenic activity in the neonatal male B6C3F1 mouse. After determinations of the maximum tolerated dose (MTD), both aromatic amines were administered i.p. at 2 dose levels (MTD and MTD/2) on days 1, 8, 15 and 22 after birth. Groups were killed at 9 and 12 months and examined for histopathologic changes. No treatment-related neoplastic lesions were observed for 2-APP. In contrast, 4-ABP was strongly carcinogenic and induced a high incidence of multiple hepatocellular adenomas and carcinomas.

Aminobiphenyl Compounds↗
PubMed1985

[Developments in research on mycotoxins].

Since the early 1960's attention has been paid to mycotoxins by various disciplines of the National Institute of Public Health and Environmental Hygiene (RIVM) (Analytical Chemistry, Microbiology, Toxicology). A major part of the work is carried out at the request of the Chief Medical Office. The activities undertaken on behalf of the Chief Veterinary Officer concern investigations on the causes of fungal growth and toxin production as well as on the presence of aflatoxin B1 and the analytical possibilities of determining aflatoxin B1 in feeds and aflatoxin M1 in milk. Because of its structural relationship with aflatoxin B1, aflatoxin M1 is suspected of having carcinogenic properties. In order to be able to do chronic toxicity studies in rats, efforts are being made to synthesize approximately 25 g. of aflatoxin M1 in co-operation with the State University of Utrecht, which was found to be a time-consuming and extremely difficult job. From the point of view of the Chief Veterinary Officer, it is expected that the analytical and toxicological features of aflatoxin M1 will continue to be of interest in the near future.

Aflatoxin B1↗
PubMed1985

Syntheses of 5-phenyl-2-pyridinamine, a possibly carcinogenic pyrolysis product of phenylalanine, and some of its putative metabolites.

5-Phenyl-2-pyridinamine (PPA) is a pyrolysis product of phenylalanine, the presence of which has been demonstrated in broiled sardines. Since PPA is mutagenic in the Ames test and is structurally related to the aminobiphenyls, it has to be considered as potentially carcinogenic. In this study procedures for the synthesis of PPA and its possible metabolites were developed to make them available for biological studies. PPA was synthesized in one step from 2,5-pyridinediamine. However, this method is only suitable for the preparation of small amounts. Larger quantities were synthesized starting from 5-nitro-2-pyridinamine in four steps. PPA was also prepared via a six-step synthesis, starting from 6-amino-3-pyridinecarboxamide. This route was also used for the synthesis of tritiated PPA [( 3H]PPA) and 2-nitro-5-phenylpyridine, the latter being the precursor of the two putative proximate carcinogenic metabolites, viz. the hydroxylamine and the hydroxamic acid of PPA. In the course of these multi-step syntheses a new method for the preparation of unsymmetrical biaryls was worked out. The following possible metabolites were also synthesized: N-(5-phenyl-2-pyridinyl)acetamide in the course of the synthesis of PPA starting from 5-nitro-2-pyridinamine, and both 5-(4-hydroxyphenyl)-2-pyridinamine (4'-OH-PPA) and N-[5-(4-hydroxyphenyl)-2-pyridinyl]acetamide starting from 5-(4-aminophenyl)-2-pyridinamine. After incubation of PPA in suspensions of freshly isolated hepatocytes from rats pretreated with polychlorinated biphenyls (Aroclor 1254) or PPA itself, the presence of 4'-OH-PPA was demonstrated.

Aminopyridines↗
PubMed1984

Induction of ornithine decarboxylase and augmentation of tyrosine aminotransferase activity by N-hydroxy-2-acetylaminofluorene and 2-acetylaminofluorene in rat liver. Influence of sex, retinylacetate, indomethacin, and pentachlorophenol.

IP injection in rats of 2-acetylaminofluorene (AAF) or N-hydroxy-2-acetylaminofluorene (N-OH-AAF) resulted in a transient increase of hepatic ornithine decarboxylase (ODC) and tyrosine aminotransferase (TAT) activity. Maximal activity of ODC was observed 4 hr and of TAT 3 hr after administration of either AAF or N-OH-AAF. A lag-time of 2 hr preceded the increase of ODC and TAT activity. N-OH-AAF dependent ODC induction displayed an almost linear dose-response in the dose range up to 94.1 mumol/kg bw (body weight) when the ODC activity was measured at its maximum 4 hr after administration. Elevation of the dose N-OH-AAF to 126 mol/kg bw resulted in a lower ODC induction. Administration of doses AAF to 31.4 mumol did not change ODC activity. At doses up to 126 mumol/kg bw ODC induction increased linear. TAT induction increased linear in the dose range 15.7-94.1 mumol N-OH-AAF and 31.4-94.1 mumol AAF/kg. Lowering the dose of AAF did not result in a lower ODC or TAT activity. Judged by the effects of actinomycin D or cycloheximide administered 1 hr prior to AAF or N-OH-AAF, the in vivo induction of rat liver ODC activity by AAF and N-OH-AAF appeared to be under transcriptional control, whereas augmentation of TAT activity under influence of AAF or N-OH-AAF appeared the result of (post) translational events. Induction of ODC by AAF or N-OH-AAF was not significantly changed by indomethacin, was slightly increased by pentachlorophenol (PCP) and was synergistically enhanced by retinylacetate (RA). The increase of TAT activity was stimulated by PCP and RA. The effect of PCP indicates that N-sulfonoxy-2-acetylaminofluorene is most probably not involved in the induction of ODC. AAF appeared more effective hepatic ODC inducer in females than males and moreover more effective than N-OH-AAF in females. N-OH-AAF had stronger ODC inducing capacity in males than females. Similar observations were made with respect to TAT activity. When induction of ODC is indicative for a tumor promoting property then the data presented here suggest that tumor promotion of the complete carcinogens AAF and N-OH-AAF is not mediated by N-O-sulfation; this might be due to other metabolic conversions.

2-Acetylaminofluorene↗