Metabolism and excretion of 1-hydroxymethylpyrene, the proximate metabolite of the carcinogen 1-methylpyrene, in rats.

1-Methylpyrene, an alkylated polycyclic aromatic hydrocarbon and environmental carcinogen, is activated by side-chain hydroxylation to 1-hydroxymethylpyrene (1-HMP) and subsequent sulfo conjugation to the DNA-reactive 1-sulfooxymethylpyrene. In addition to the bioactivation, processes of metabolic detoxification and transport greatly influence the genotoxicity of 1-methylpyrene. For a better understanding of 1-HMP detoxification in vivo we studied urinary and fecal metabolites in rats following intraperitoneal doses of 19.3mg 1-HMP/kg body weight (5 rats) or the same dose containing 200µCi [(14)C]1-HMP/kg body weight (2 rats). After 48h, 48.0% (rat 1) and 29.1% (rat 2) of the radioactivity was recovered as 1-HMP in the feces. Six major metabolites were observed by UV and on-line radioactivity detection in urine samples and feces after HPLC separation. The compounds were characterized by mass spectrometry, (1)H NMR and (1)H-(1)H COSY NMR spectroscopy, which allowed assigning tentative molecular structures. Two prominent metabolites, 1-pyrene carboxylic acid (M-6) and the acyl glucuronide of 1-pyrene carboxylic acid (M-5) accounted for 17.7% (rat 1) and 25.2% (rat 2) of the overall radioactive dose. Further, we detected the acyl glucuronide of 6-hydroxy-1-pyrene carboxylic acid (M-1) and 8-sulfooxy-1-pyrene carboxylic acid (M-3) together with two regioisomers of M-3 (M-2 and M-4) differing in position of the sulfate group at the pyrene ring. In urine samples, the radioactivity of 1-pyrene carboxylic acid and its five derivatives amounted to 32.4% (rat 1) or 45.5% (rat 2) of the total [(14)C]1-HMP dose.

Four new flavonol glycosides from the leaves of Brugmansia suaveolens.

Four new flavonol glycosides were isolated from the leaves of Brugmansia suaveolens: kaempferol 3-O-ß-D-glucopyranosyl-(1'''→2'')-O-α-L-arabinopyranoside (1), kaempferol 3-O-ß-D-glucopyranosyl-(1'''→2'')-O-α-L-arabinopyranoside-7-O-i-D-gluco-pyranoside (2), kaempferol 3-O-ß-D-[6'''-O-(E-caffeoyl)]-glucopyranosyl-(1'''→2'')-O-α-l-arabinopyranoside-7-O-ß-D-glucopyranoside (3), and kaempferol 3-O-ß-D-[2'''-O-(E-caffeoyl)]-glucopyranosyl-(1'''→2'')-O-α-l-arabinopyranoside-7-O-ß-D-glucopyranoside (4). The structure elucidation was performed by MS, 1D and 2D NMR analyses.

Monitoring the on-line titration of enantiomeric omeprazole employing continuous-flow capillary microcoil 1H NMR spectroscopy.

The titration of the (S)-enantiomer of omeprazole with the (R)-enantiomer in chloroform-d(1) is monitored by continuous-flow capillary microcoil (1)H NMR spectroscopy employing a microcoil with a detection volume of 1.5 µl. The observed changes of the (1)H NMR chemical shifts indicate the formation of a heterochiral (R,S) dimer of omeprazole via its sulfinyl group and the NH group of the benzimidazole ring.

Detection of DNA adducts originating from 1-methoxy-3-indolylmethyl glucosinolate using isotope-dilution UPLC-ESI-MS/MS.

1-Methoxy-3-indolylmethyl (1-MIM) glucosinolate, present at substantial levels in several food crops (e.g., broccoli and cabbage), forms DNA adducts in vitro and is mutagenic to bacterial and mammalian cells after activation by the plant enzyme myrosinase. Moreover, a breakdown product, 1-MIM alcohol, is metabolized to a secondary reactive intermediate by some mammalian sulfotransferases (SULTs). First, we incubated herring-sperm DNA with 1-MIM glucosinolate in the presence of myrosinase. We identified and synthesized the predominant adducts, N(2)-(1-MIM)-dG and N(6)-(1-MIM)-dA, and developed an UPLC-ESI-MS/MS method for their specific detection using isotopic dilution. Second, we demonstrated both DNA adducts in target cells (Salmonella typhimurium TA100 and Chinese hamster V79) of standard mutagenicity tests treated with 1-MIM glucosinolate/myrosinase as well as in 1-MIM alcohol-treated Salmonella and V79 cells engineered for expression of human SULT1A1. Similar excesses of N(2)-(1-MIM)-dG over N(6)-(1-MIM)-dA adducts were found in all cellular models independent of the test compound (1-MIM glucosinolate or alcohol), whereas dA adducts predominated in the cell-free system. Finally, we detected both DNA adducts in colon tissue of a mouse orally treated with 1-MIM glucosinolate. We are going to use this specific and sensitive method for investigating genotoxic risks of food-borne exposure to 1-MIM glucosinolate in animal and human studies.

Time-dependent column performance of cholesterol-based stationary phases for HPLC by LC characterization and solid-state NMR spectroscopy.

Three different cholesterol-based stationary phases were investigated with respect to their time-dependent separation behavior. The examined stationary phases differ in the used spacer molecule and the synthesis route and were used under routine laboratory conditions over a period of two years. The chromatographic behavior of the three phases was determined by using a standard reference material in addition to a separation of a steroid mixture. The surface chemistry and the modification of these with the chemically bonded moiety were investigated with nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Through applying different techniques we determined changes in retention and selectivity; solid-state NMR spectra showed changes in the surface chemistry dependent on the synthesis route. Superior long-term stability was observed for the undecanoate-cholesterol (UDC-Chol) column in terms of hydrophobic retentiveness and selectivity.