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.

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.

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.

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.

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.