A new minor metabolite of 5-fluorocytosine, 5-hydroxy-5-fluorocytosine, was found in the urinary gravel excreted by a patient being treated with this drug. A metabolite of 5-fluorocytosine in animals, alpha-fluoro-beta-alanine, was identified and quantitated in the urine of nine patients. In general, alpha-fluoro-beta-alanine represented 0.05--0.25% of the daily dose of 5-fluorocytosine, both for orally and intravenously administered drug. Minor metabolites have been implicated in the occasional toxicity observed in patients receiving 5-fluorocytosine.
1. Six new metabolites of quinine have been identified in urine of man by methane chemical ionization g.l.c.--mass spectrometry. 2. Metabolites identified were: unchanged quinine and dihydroquinine, 3-hydroxyquinine, 3-hydroxydihydroquinine, 6'-hydroxycinchonidine, 6'-hydroxydihydrocinchonidine, quinine-10,11-epoxide and quinine-10,11-dihydrodiol. 3. 10-Chloro-11-hydroxydihydroquinine was identified as an artifact of the isolation procedure. 4. Chloroquine and desethylchloroquine (artifacts) were identified in the urine, 17 days after completion of a 48 h treatment with chloroquine.
Isobutane chemical ionization gas chromatography mass spectometry of the N-trifluoroacetyl-carboxy-n-butyl ester derivatives of amino acids, using a commercial per-13C-amino acid mixture as internal standards, provided a sensitive and specific method for quantitative analysis of fourteen urinary alpha-amino acids. A computer controlled quadrupole mass spectrometer was used in a selected ion monitoring mode to record the ion current due to the protonated molecular ions of each alpha-amino acid/13C analogue pair. BASIC programmes located peak maxima, and using previously established standard curves, calculated the amino acid content on the bases of both peak height and peak area ratios. Duplicate amino acid analyses are possible on 5 microliter of urine. Instrumental analysis required 25 minutes, automated data processing 10 minutes, and sample preparation 2 hours. Detection limits approached 1 ng with a typical mean standard deviation of 2% for the instrumental analysis.
Methane-, isobutane-and vinyl methyl ether-chemical ionization mass spectra were unsatisfactory for discrimination between cyclopropanoid fatty acid methyl esters and their monoene isomers using packed column gas chromatography mass spectrometry. A methodology was developed whereby these isomers could be distinguished by using a mixture of methane and vinyl methyl ether as the chemical ionization reactant gas. The spectra of the monoene fatty acid methyl esters displayed a series of vinyl methyl ether adduct ions, which were less than one-tenth as abundant in the spectra of the isomeric CycIopropanoid compounds. A greater degree of discrimination was achieved using isobutane/vinyl methyl ether as a mixed reagent gas, when unsaturated fatty acid methyl esters yielded a vinyl methyl ether adduct ion which was essentially absent (reduced to approx. 2%) in the spectrum of the isomeric cyclopropanoids. These adduct ions could be used to clearly define the occurrence of the monoenoic compounds in the presence of isomeric cyclopropanoids. Examples of the use of this method, in conjunction with catalytic hydrogenation, for the identification of cyclopropanoid fatty acid methyl esters in several Thiobacilius spp. and of monounsaturated fatty acid methyl esters in the fungus, Trametes lilacinogilva, are presented.
The neutral lipid fraction of two strains of T. thioparus was examined using gas chromatographychemical ionization mass spectrometry. Both strains were found to produce fatty acid ethyl esters, long-chain alcohols and. wax esters. In addition, one strain produced substantial quantities of squalene, although no sterols or triterpenoids could be detected. However, in the second strain, although squalene was present at greatly reduced levels, cholesterol, lanosteryl acetate and 24,25-dihydrolanosteryl acetate were identified.
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