![]() |
|
|
Vol. 30, Issue 5, 564-569, May 2002
Structural Requirements
Department of Cell and Molecular Pharmacology and Experimental
Therapeutics, Medical University of South Carolina, Charleston,
South Carolina
Recent studies in our laboratory in the human hepatic and
intestinal cell lines Hep G2 and Caco-2 have demonstrated induction of
UGT1A1 by the flavonoid chrysin (5,7-dihydroxyflavone) using catalytic
activity assays and Western and Northern blotting. In the present
study, we examined which features of the flavonoid structures were
associated with induction of UGT1A1 and whether common
drug-metabolizing enzyme inducers also produce this induction. We also
determined whether flavonoid treatment affected sulfate conjugation and
CYP1A1 activity. We used intact Hep G2 cells for these studies, with
chrysin as the model substrate. Both glucuronidation and sulfation were
measured. Hep G2 cells were pretreated for 3 days with 25 µM
concentrations of 22 flavonoids (n = 4-12). Only
four flavonoids demonstrated induction of glucuronidation similar to
that of chrysin (i.e., 3-5-fold in the intact cells). These were
acacetin, apigenin, luteolin, and diosmetin, all of which, like
chrysin, are 5,7-dihydroxyflavones with varying substituents in the
B-ring. 5-Hydroxy-7-methoxyflavone and 5-methyl-7-hydroxyflavone produced a modest 1.5 to 2-fold induction, whereas all other flavonoids examined were without effect. None of the flavonoids caused more than a
modest change in sulfation activity (60-140% of control). In
contrast, all tested 5,7-dihydroxyflavones and -flavonols induced CYP1A1 activity (ethoxyresorufin deethylation). Of seven common drug-metabolizing enzyme inducers only 3-methylcholanthrene and oltipraz showed modest induction of chrysin glucuronidation but not
2,3,7,8-tetrachlorodibenzo-p-dioxin or
phenobarbital. Together, these results strongly suggest that the
flavonoid induction of UGT1A1 is through a novel nonaryl hydrocarbon
receptor-mediated mechanism.
This article has been cited by other articles:
![]() |
S. L. Navarro, S. Peterson, C. Chen, K. W. Makar, Y. Schwarz, I. B. King, S. S. Li, L. Li, M. Kestin, and J. W. Lampe Cruciferous Vegetable Feeding Alters UGT1A1 Activity: Diet- and Genotype-Dependent Changes in Serum Bilirubin in a Controlled Feeding Trial Cancer Prevention Research, April 1, 2009; 2(4): 345 - 352. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Mirkov, B. J. Komoroski, J. Ramirez, A. Y. Graber, M. J. Ratain, S. C. Strom, and F. Innocenti Effects of Green Tea Compounds on Irinotecan Metabolism Drug Metab. Dispos., February 1, 2007; 35(2): 228 - 233. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. M. Smith, R. A. Graham, W. L. Krol, I. S. Silver, M. Negishi, H. Wang, and E. L. Lecluyse Differential UGT1A1 Induction by Chrysin in Primary Human Hepatocytes and HepG2 Cells J. Pharmacol. Exp. Ther., December 1, 2005; 315(3): 1256 - 1264. [Abstract] [Full Text] [PDF] |
||||
![]() |
X. Wen, U.K. Walle, and T. Walle 5,7-Dimethoxyflavone downregulates CYP1A1 expression and benzo[a]pyrene-induced DNA binding in Hep G2 cells Carcinogenesis, April 1, 2005; 26(4): 803 - 809. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. Svehlikova, S. Wang, J. Jakubikova, G. Williamson, R. Mithen, and Y. Bao Interactions between sulforaphane and apigenin in the induction of UGT1A1 and GSTA1 in CaCo-2 cells Carcinogenesis, September 1, 2004; 25(9): 1629 - 1637. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. G. Soars, D. M. Petullo, J. A. Eckstein, S. C. Kasper, and S. A. Wrighton AN ASSESSMENT OF UDP-GLUCURONOSYLTRANSFERASE INDUCTION USING PRIMARY HUMAN HEPATOCYTES Drug Metab. Dispos., January 1, 2004; 32(1): 140 - 148. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Hu, J. Chen, and H. Lin Metabolism of Flavonoids via Enteric Recycling: Mechanistic Studies of Disposition of Apigenin in the Caco-2 Cell Culture Model J. Pharmacol. Exp. Ther., October 1, 2003; 307(1): 314 - 321. [Abstract] [Full Text] [PDF] |
||||
![]() |
M.-F. Yueh, Y.-H. Huang, A. Hiller, S. Chen, N. Nguyen, and R. H. Tukey Involvement of the Xenobiotic Response Element (XRE) in Ah Receptor-mediated Induction of Human UDP-glucuronosyltransferase 1A1 J. Biol. Chem., April 18, 2003; 278(17): 15001 - 15006. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Chen, H. Lin, and M. Hu Metabolism of Flavonoids via Enteric Recycling: Role of Intestinal Disposition J. Pharmacol. Exp. Ther., March 1, 2003; 304(3): 1228 - 1235. [Abstract] [Full Text] [PDF] |
||||