Document Detail

Piperine-mediated inhibition of glucuronidation activity in isolated epithelial cells of the guinea-pig small intestine: evidence that piperine lowers the endogeneous UDP-glucuronic acid content.
MedLine Citation:
PMID:  3080587     Owner:  NLM     Status:  MEDLINE    
Piperine (1-peperoyl piperidine), a major component of the Piper species was reported recently by us to inhibit the activities of rat hepatic monooxygenases and UDP-glucuronyltransferase. This study explores further the basis of inhibition of glucuronidation. The effect of piperine on the rate of glucuronidation of 3-hydroxybenzo(a) pyrene and UDP-glucuronic acid content in the intact isolated epithelial cells of the guinea-pig small intestine was studied. The cells offered a fairly good system to study the modulation of glucuronidation activity. Glucuronidation of 3-hydroxybenzo(a) pyrene was dependent on the time of incubation, cellular protein and substrate concentration. From the kinetics of glucuronidation of 3-hydroxybenzo(a)pyrene in the isolated cell preparation the Vmax of 0.5 nmol of BP-3-glucuronide formed per min/mg of protein and Km of 25 microM were observed. The endogeneous concentration of UDP-glucuronic acid observed was 1.6 to 2.3 nmol/mg of cellular protein. Piperine caused a concentration-related decrease in UDP-glucuronic acid content and the rate of glucuronidation in the cells. It required much lower concentrations of piperine than D-galactosamine to diminish the endogeneous level of UDP-glucuronic acid. Rate of glucuronidation of 3-hydroxybenzo (a) pyrene was dependent on the endogeneous level of UDP-glucuronic acid. At 50 microM piperine, the rate of glucuronidation was reduced to about 50% of the basal rate. Piperine caused noncompetitive inhibition of hepatic microsomal UDP-glucuronyltransferase with Ki of 70 microM. The studies demonstrate that piperine modifies the rate of glucuronidation by lowering the endogeneous UDP-glucuronic acid content and also by inhibiting the transferase activity.
J Singh; R K Dubey; C K Atal
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of pharmacology and experimental therapeutics     Volume:  236     ISSN:  0022-3565     ISO Abbreviation:  J. Pharmacol. Exp. Ther.     Publication Date:  1986 Feb 
Date Detail:
Created Date:  1986-03-18     Completed Date:  1986-03-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0376362     Medline TA:  J Pharmacol Exp Ther     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  488-93     Citation Subset:  IM    
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MeSH Terms
Benzopyrenes / metabolism
Cell Survival / drug effects
Epithelium / metabolism
Galactosamine / pharmacology
Glucuronates / metabolism*
Glucuronosyltransferase / antagonists & inhibitors
Guinea Pigs
Intestine, Small / metabolism*
Piperidines / pharmacology*
Polyunsaturated Alkamides
Uridine Diphosphate Glucuronic Acid / analysis*,  metabolism
Uridine Diphosphate Sugars / analysis*
Reg. No./Substance:
0/Alkaloids; 0/Benzodioxoles; 0/Benzopyrenes; 0/Glucuronates; 0/Piperidines; 0/Polyunsaturated Alkamides; 0/Uridine Diphosphate Sugars; 13345-21-6/3-hydroxybenzo(a)pyrene; 2616-64-0/Uridine Diphosphate Glucuronic Acid; 7535-00-4/Galactosamine; 7780-20-3/piperine; EC

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