Jason P. Burgess

Metabolomics in the assessment of chemical-induced reproductive and developmental outcomes using non-invasive biological fluids: application to the study of butylbenzyl phthalate

This study was conducted to evaluate the use of metabolomics for improving our ability to draw correlations between early life exposures and reproductive and/or developmental outcomes. Pregnant CD rats were exposed by gavage daily during gestation to vehicle or to butylbenzyl phthalate (BBP) in vehicle at a level known to induce effects in the offspring and at a level previously not shown to induce effects. Urine was collected for 24 h (on dry ice using all glass metabolism chambers) from dams on gestational day 18 (during exposure) and on post natal day (pnd) 21, and from pnd 25 pups. Traditional phenotypic anchors were measured in pups (between pnd 0 and pnd 26). Metabolomics of urine collected from dams exposed to vehicle or BBP exhibited different patterns for endogenous metabolites. Even three weeks after gestational exposure, metabolic profiles of endogenous compounds in urine could differentiate dams that received the vehicle, low dose or high dose of BBP. Metabolic profiles could differentiate male from female pups, pups born to dams receiving the vehicle, low or high BBP dose, and pups with observable adverse reproductive effects from pups with no observed effects. Metabolites significant to the separation of dose groups and their relationship with effects measured in the study were mapped to biochemical pathways for determining mechanistic relevance. The application of metabolomics to understanding the mechanistic link between low levels of environmental exposure and disease/dysfunction holds huge promise, because this technology is ideal for the analysis of biological fluids in human populations. Copyright

Reaction of the Butter Flavorant Diacetyl (2,3-Butanedione) with N-α-Acetylarginine: A Model for Epitope Formation with Pulmonary Proteins in the Etiology of Obliterative Bronchiolitis

The butter flavorant diacetyl (2,3-butanedione) is implicated in causing obliterative bronchiolitis in microwave popcorn plant workers. Because diacetyl modifies arginine residues, an immunological basis for its toxicity is under investigation. Reaction products of diacetyl with N-α-acetylarginine (AcArg) were determined as a model for hapten formation, with characterization by mass spectrometry, NMR, and HPLC with UV detection and radiodetection. Four products were identified by LC-MS, each with a positive ion of m/z 303 (diacetyl + AcArg); one pair displayed an additional ion at m/z 217 (AcArg), the other pair at m/z 285 (- H(2)O). Their (1)H-(13)C NMR correlation spectra were consistent with the addition of one or two of the guanidine nitrogens to form aminols. Open-chain pairs interconverted at pH 2, as did the cyclized, but all four interconverted at neutral pH. This is the first structural characterization of the covalent adducts between diacetyl and an arginine moiety.

Pyrrolizidine alkaloids from Echium glomeratum (Boraginaceae).

The methanolic extract of the whole plant of Echium glomeratum Poir. (Boraginaceae) has afforded five pyrrolizidine alkaloids, three that were (7S, 8R)-petranine (1), (7S, 8S)-petranine (2), and (7R, 8R)-petranine (3a) or (7R, 8S)-petranine (3b), comprising a tricyclic pyrrolizidine alkaloids subclass; and two that were known but to the species: 7-angeloylretronecine (4) and 9-angeloylretronecine (5). All compounds were tested against a human tumor panel for cytotoxicity; no activity was observed (EC50 values>20microg/ml).

Rapid in-plate generation of benzimidazole libraries and amide formation using EEDQ

Abstract A solution phase method for the preparation of etonitazene-related benzimidazoles and a general method for the preparation of amide derivatives in 96-well format have been developed for the generation of libraries of compounds in parallel.

Phytochemical studies and cytotoxicity evaluations of Colchicum tunicatum Feinbr and Colchicum hierosolymitanum Feinbr (Colchicaceae): Two native Jordanian meadow saffrons.

As a part of our continuing investigation of Jordanian Colchicum species, the biologically active components of Colchicum hierosolymitanum Feinbr and Colchicum tunicatum Feinbr (Colchicaceae) were pursued. The brine shrimp lethality test (BSLT) was used to direct the fractionation and isolation of active components. Five and four known colchicinoids were isolated and characterized from C. tunicatum and C. hierosolymitanum, respectively. The known colchicinoids, reported for the first time from these two species are: (−)-colchicine (I), 3-demethyl-(−)-colchicine (II), (−)-cornigerine (III), β-lumicolchicine (IV), and (−)-androbiphenyline (V) from C. tunicatum, and (−)-colchicine (I), 2-demethyl-(−)-colchicine (VI), (−)-cornigerine (III), and β-lumicolchicine (IV) from C. hierosolymitanum. The chemical structures of the isolated compounds have been elucidated using a series of spectroscopic and spectrometric techniques principally; 1D-NMR (1H and 13C) and low resolution EI-MS and APCIMS. All pure compounds were evaluated for cytotoxicity against three human cancer cell lines; MCF-7 human breast carcinoma, NCI-H460 human large cell lung carcinoma, and SF-268 human astrocytoma. (−)-Colchicine (I) and (−)-cornigerine (III) were found to be the most bioactive of the identified compounds with EC50 values in the range of 0.016–0.097 μM.

(±)-4-[(N-allyl-CIS-3-methyl-4-piperidinyl)phenylamino]-N, N-diethylbenzamide displays selective binding for the delta opioid receptor

Racemic 4-[(N-allyl-cis-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzam ide (3a) was synthesized and found to have good affinity and selectivity for the delta receptor. These compounds can be viewed as an analog of BW373U86 and SNC-80 where an internal piperazine nitrogen has been transposed with a benzylic carbon. Functionally, 3a behaves as an agonist at the delta receptor with no measurable stimulation of either the mu or kappa receptor subtypes and was found to be devoid of any measurable amount of antagonist activity for any opioid receptor. A comparison of 3a to SNC-80 and DPDPE in the [35S]GTPgammaS functional assay suggests that 3a may be more like the peptide DPDPE.

CYP2E1-Catalyzed Oxidation Contributes to the Sperm Toxicity of 1-Bromopropane in Mice

Abstract 1-Bromopropane (1-BrP) induces dose- and time-dependent reproductive organ toxicity and reduced sperm motility in rodents. The contribution of cytochrome P4502E1 (CYP2E1) to both 1-BrP metabolism and the induction of male reproductive toxicity was investigated using wild-type (WT) and Cyp2e1−/− mice. In gas uptake inhalation studies, the elimination half-life of [1,2,3-13C]-1-BrP was longer in Cyp2e1−/− mice relative to WT (3.2 vs. 1.3 h). Urinary metabolites were identified by 13C nuclear magnetic resonance. The mercapturic acid of 1-bromo-2-hydroxypropane (2OHBrP) was the major urinary metabolite in WT mice, and products of conjugation of 1-BrP with glutathione (GSH) were insignificant. The ratio of GSH conjugation to 2-hydroxylation increased 5-fold in Cyp2e1−/− mice relative to WT. After 1-BrP exposure, hepatic GSH was decreased by 76% in WT mice vs. 47% in Cyp2e1−/− mice. Despite a 170% increase in 1-BrP exposure in Cyp2e1−/− vs. WT mice, sperm motility in exposed Cyp2e1−/− mice did not change relative to unexposed matched controls. This suggests that metabolites produced through CYP2E1-mediated oxidation may be responsible for 1-BrP-induced sperm toxicity. Both 1-BrP and 2OHBrP inhibited the motility of sperm obtained from WT mice in vitro. However, only 2OHBrP reduced the motility of sperm obtained from Cyp2e1−/− mice in vitro, suggesting that conversion of parent compound to 2OHBrP within the spermatozoa may contribute, at least in part, to reduced motility. Overall, these data suggest that metabolism of 1-BrP is mediated in part by CYP2E1, and activation of 1BrP via this enzyme may contribute to the male reproductive toxicity of this chemical.

Conformationally constrained analogues of N-(piperidinyl)-5-(4-chlorophenyl)-1-(2,4- dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716): design, synthesis, computational analysis, and biological evaluations.

Structure-activity relationships (SARs) of 1 (SR141716) have been extensively documented, however, the conformational properties of this class have received less attention. In an attempt to better understand ligand conformations optimal for receptor recognition, we have designed and synthesized a number of derivatives of 1, including a four-carbon-bridged molecule (11), to constrain rotation of the diaryl rings. Computational analysis of 11 indicates approximately 20 kcal/mol energy barrier for rotation of the two aryl rings. NMR studies have determined the energy barrier to be approximately 18 kcal/mol and suggested atropisomers could exist. Receptor binding and functional studies with these compounds displayed reduced affinity and potency when compared to 1. This indicates that our structural modifications either constrain the ring systems in a suboptimal orientation for receptor interaction or the introduction of steric bulk leads to disfavored steric interactions with the receptor, and/or the relatively modest alterations in the molecular electrostatic potentials results in disfavored Coulombic interactions.

4-[(8-Alkyl-8-azabicyclo[3.2.1]octyl-3-yl)-3-arylanilino]-N,N-diethylbenzamides: high affinity, selective ligands for the delta opioid receptor illustrate factors important to antagonist activity

The tropane derived compounds, 4-[(8-alkyl-8-azabicyclo[3.2.1]octyl-3-yl)-3-arylanilino]-N,N-d iethylbenzamides (5a-d), were synthesized and found to have high affinity and selectivity for the delta receptor. Compounds 5a-d are structurally similar to the full agonist (-)-RTI-5989-54 (3); yet, efficacy studies for compounds in this series (5a-d) reveal greatly diminished agonist activity as well as antagonism not found in piperidine-based compounds like 3.

A stereoselective synthetic approach to N-alkyl-4β-methyl-5-phenylmorphans

Abstract A convergent, highly stereoselective synthetic approach to N-alkyl-4β-methyl-5-phenylmorphans has been developed utilizing alkylation of the metalloenamine of N-alkyl-1,2,3,6-tetrahydro-4-phenylpyridines with 2-(chloromethyl)-3,5-dioxahex-1-ene (Okaharas reagent) followed by Clemmensen reduction.