N-Glucosylation has been thought to be an important pathway for lower life forms but insignificant in mammals. Continued evidence suggests that in man the formation and/or urinary excretion of N-glucoside metabolites of barbiturates may be very important, is stereospecific and may play a complementary role to glucuronidation. Studies are designed to determine if the mouse is a suitable animal model for further study of the N-glucosylation pathway that has been observed in humans. Phenobarbital will be used in the initial studies since it is clinically the most important barbiturate used in humans. A sensitive radiochemical assay will be used to measure phenobarbital N-glucosylation in vitro using mouse liver microsomes and to characterize this N-glucosyltransferase enzyme. This assay will be used to determine what other endogenous and exogenous compounds can affect the N-glucosylation of phenobarbital. These studies will develop the first structure-substrate relationship for N-glucosylation in which absorption, distribution, metabolism and excretion will not be interfering variables. Metabolism studies using 14C-phenobarbital will be done in mice to determine if the mouse forms additional glycoside conjugates of phenobarbital. Additional studies are designed to determine the relationship of the PB N-glucoside pathway with the xenobiotic glucuronidation pathway by comparing the effect of sex, strain, xenobiotics and age on phenobarbital N-glucosylation versus p-nitrophenol glucuronidation. Finally, synthetic methodology will be developed to confirm structure and determine stereochemistry of new imide N-glucoside metabolites discovered during these studies.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM034507-04A2
Application #
3285644
Study Section
Pharmacology A Study Section (PHRA)
Project Start
1986-07-16
Project End
1994-07-31
Budget Start
1991-08-01
Budget End
1992-07-31
Support Year
4
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Virginia Commonwealth University
Department
Type
Schools of Pharmacy
DUNS #
City
Richmond
State
VA
Country
United States
Zip Code
23298
Nandi, V; Soine, W H (1997) HPLC analysis for amobarbital N-glycosides in urine. J Pharm Biomed Anal 15:1187-95
Neighbors, S M; Soine, W H (1995) Identification of phenobarbital N-glucuronides as urinary metabolites of phenobarbital in mice. Drug Metab Dispos 23:548-52
Soine, W H; Soine, P J; England, T M et al. (1994) Identification of the diastereomers of pentobarbital N-glucosides excreted in human urine. Pharm Res 11:1535-9
Soine, W H; Graham, R M; Soine, P J (1992) Identification of 5-ethyl-5-(2-methylbutyl)barbituric acid as an impurity of manufacture in amobarbital. J Pharm Sci 81:362-4
Soine, W H; Safi, H; Westkaemper, R B (1992) Initial studies on the N-glucosylation of phenobarbital by mouse liver microsomes using a radiochemical high-performance liquid chromatographic (HPLC) method. Pharm Res 9:613-6
Soine, W H; Soine, P J; England, T M et al. (1991) Identification of phenobarbital N-glucosides as urinary metabolites of phenobarbital in mice. J Pharm Sci 80:99-103
Mongrain, S E; Soine, W H (1991) Product enantioselectivity in the N-glucosylation of amobarbital by cats. Drug Metab Dispos 19:1012-3
Soine, W H; Soine, P J; England, T M (1991) Barbital N-glucoside is not detected as a urinary excretion product of barbital in humans. J Pharm Biomed Anal 9:747-52
Soine, W H; Soine, P J; England, T M et al. (1990) LC determination of the diastereomers of 1-(beta-D-glucopyranosyl)phenobarbital in human urine. J Pharm Biomed Anal 8:365-72
Soine, W H; Soine, P J; Wireko, F C et al. (1990) Stereochemical characterization of the diastereomers of the amobarbital N-glucosides excreted in human urine. Pharm Res 7:794-800

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