UDP-glucuronosyltransferase 1A6 is the major isozyme responsible for protocatechuic aldehyde glucuronidation in human liver microsomes

Hui Xin Liu, Yong Liu, Jiang Wei Zhang, Wei Li, Hong Tao Liu, Ling Yang

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Glucuronidation is an important pathway in the metabolism of protocatechuic aldehyde (3,4-dihydroxybenzaldehyde, PAL). However, the metabolites and primary UDP-glucuronosyltransferase (UGT) isozymes responsible for PAL glucuronidation remain to be determined in human. Here, we characterized PAL glucuronidation by human liver microsomes (HLMs), human intestine microsomes (HIMs), and 12 recombinant UGT (rUGT) isozymes to identify what kinds of metabolites are present and which human UGT isozymes are involved. Two metabolites (M-1 and M-2) were detected in reactions catalyzed by HLMs, HIMs, rUGT1A6, and rUGT1A9 and were identified as monoglucuronides by liquid chromatographymass spectrometry. A kinetic study showed that PAL glucuronidation by rUGT1A6, rUGT1A9, HIMs, and HLMs followed Michaelis-Menten kinetics. The Km values of HLMs, HIMs, rUGT1A6, and rUGT1A9 for PAL glucuronidation were as follows: 432.7 ± 24.5, 626.9 ± 49.2, 367.5 ± 25.1, and 379.9 ± 42.5 μM for M-1 and 336.7 ± 15.3, 494.3 ± 48.7, 211.4 ± 13.4, and 238.5 ± 26.2 μM for M-2, respectively. The PAL glucuronidation activity was significantly correlated with UGT1A6 activity rather than with UGT1A9 activity from 15 individual HLMs. A chemical inhibition study showed that the IC50 for phenylbutazone inhibition of PAL glucuronidation was similar in HLMs (61.9 ± 7.9 μM) compared with rUGT1A6 (45.3 ± 7.7 μM). In contrast, androsterone inhibited rUGT1A9-catalyzed and HLM-catalyzed PAL glucuronidation with IC50 values of 27.1 ± 3.8 and >500 μM, respectively. In combination, we identified UGT1A6 as the major isozyme responsible for PAL glucuronidation in HLMs.

Original languageEnglish (US)
Pages (from-to)1562-1569
Number of pages8
JournalDrug Metabolism and Disposition
Volume36
Issue number8
DOIs
StatePublished - Aug 1 2008

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Glucuronosyltransferase
Liver Microsomes
Isoenzymes
Microsomes
Intestines
protocatechualdehyde
Inhibitory Concentration 50
Androsterone
Phenylbutazone

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmaceutical Science

Cite this

UDP-glucuronosyltransferase 1A6 is the major isozyme responsible for protocatechuic aldehyde glucuronidation in human liver microsomes. / Liu, Hui Xin; Liu, Yong; Zhang, Jiang Wei; Li, Wei; Liu, Hong Tao; Yang, Ling.

In: Drug Metabolism and Disposition, Vol. 36, No. 8, 01.08.2008, p. 1562-1569.

Research output: Contribution to journalArticle

Liu, Hui Xin ; Liu, Yong ; Zhang, Jiang Wei ; Li, Wei ; Liu, Hong Tao ; Yang, Ling. / UDP-glucuronosyltransferase 1A6 is the major isozyme responsible for protocatechuic aldehyde glucuronidation in human liver microsomes. In: Drug Metabolism and Disposition. 2008 ; Vol. 36, No. 8. pp. 1562-1569.
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abstract = "Glucuronidation is an important pathway in the metabolism of protocatechuic aldehyde (3,4-dihydroxybenzaldehyde, PAL). However, the metabolites and primary UDP-glucuronosyltransferase (UGT) isozymes responsible for PAL glucuronidation remain to be determined in human. Here, we characterized PAL glucuronidation by human liver microsomes (HLMs), human intestine microsomes (HIMs), and 12 recombinant UGT (rUGT) isozymes to identify what kinds of metabolites are present and which human UGT isozymes are involved. Two metabolites (M-1 and M-2) were detected in reactions catalyzed by HLMs, HIMs, rUGT1A6, and rUGT1A9 and were identified as monoglucuronides by liquid chromatographymass spectrometry. A kinetic study showed that PAL glucuronidation by rUGT1A6, rUGT1A9, HIMs, and HLMs followed Michaelis-Menten kinetics. The Km values of HLMs, HIMs, rUGT1A6, and rUGT1A9 for PAL glucuronidation were as follows: 432.7 ± 24.5, 626.9 ± 49.2, 367.5 ± 25.1, and 379.9 ± 42.5 μM for M-1 and 336.7 ± 15.3, 494.3 ± 48.7, 211.4 ± 13.4, and 238.5 ± 26.2 μM for M-2, respectively. The PAL glucuronidation activity was significantly correlated with UGT1A6 activity rather than with UGT1A9 activity from 15 individual HLMs. A chemical inhibition study showed that the IC50 for phenylbutazone inhibition of PAL glucuronidation was similar in HLMs (61.9 ± 7.9 μM) compared with rUGT1A6 (45.3 ± 7.7 μM). In contrast, androsterone inhibited rUGT1A9-catalyzed and HLM-catalyzed PAL glucuronidation with IC50 values of 27.1 ± 3.8 and >500 μM, respectively. In combination, we identified UGT1A6 as the major isozyme responsible for PAL glucuronidation in HLMs.",
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T1 - UDP-glucuronosyltransferase 1A6 is the major isozyme responsible for protocatechuic aldehyde glucuronidation in human liver microsomes

AU - Liu, Hui Xin

AU - Liu, Yong

AU - Zhang, Jiang Wei

AU - Li, Wei

AU - Liu, Hong Tao

AU - Yang, Ling

PY - 2008/8/1

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N2 - Glucuronidation is an important pathway in the metabolism of protocatechuic aldehyde (3,4-dihydroxybenzaldehyde, PAL). However, the metabolites and primary UDP-glucuronosyltransferase (UGT) isozymes responsible for PAL glucuronidation remain to be determined in human. Here, we characterized PAL glucuronidation by human liver microsomes (HLMs), human intestine microsomes (HIMs), and 12 recombinant UGT (rUGT) isozymes to identify what kinds of metabolites are present and which human UGT isozymes are involved. Two metabolites (M-1 and M-2) were detected in reactions catalyzed by HLMs, HIMs, rUGT1A6, and rUGT1A9 and were identified as monoglucuronides by liquid chromatographymass spectrometry. A kinetic study showed that PAL glucuronidation by rUGT1A6, rUGT1A9, HIMs, and HLMs followed Michaelis-Menten kinetics. The Km values of HLMs, HIMs, rUGT1A6, and rUGT1A9 for PAL glucuronidation were as follows: 432.7 ± 24.5, 626.9 ± 49.2, 367.5 ± 25.1, and 379.9 ± 42.5 μM for M-1 and 336.7 ± 15.3, 494.3 ± 48.7, 211.4 ± 13.4, and 238.5 ± 26.2 μM for M-2, respectively. The PAL glucuronidation activity was significantly correlated with UGT1A6 activity rather than with UGT1A9 activity from 15 individual HLMs. A chemical inhibition study showed that the IC50 for phenylbutazone inhibition of PAL glucuronidation was similar in HLMs (61.9 ± 7.9 μM) compared with rUGT1A6 (45.3 ± 7.7 μM). In contrast, androsterone inhibited rUGT1A9-catalyzed and HLM-catalyzed PAL glucuronidation with IC50 values of 27.1 ± 3.8 and >500 μM, respectively. In combination, we identified UGT1A6 as the major isozyme responsible for PAL glucuronidation in HLMs.

AB - Glucuronidation is an important pathway in the metabolism of protocatechuic aldehyde (3,4-dihydroxybenzaldehyde, PAL). However, the metabolites and primary UDP-glucuronosyltransferase (UGT) isozymes responsible for PAL glucuronidation remain to be determined in human. Here, we characterized PAL glucuronidation by human liver microsomes (HLMs), human intestine microsomes (HIMs), and 12 recombinant UGT (rUGT) isozymes to identify what kinds of metabolites are present and which human UGT isozymes are involved. Two metabolites (M-1 and M-2) were detected in reactions catalyzed by HLMs, HIMs, rUGT1A6, and rUGT1A9 and were identified as monoglucuronides by liquid chromatographymass spectrometry. A kinetic study showed that PAL glucuronidation by rUGT1A6, rUGT1A9, HIMs, and HLMs followed Michaelis-Menten kinetics. The Km values of HLMs, HIMs, rUGT1A6, and rUGT1A9 for PAL glucuronidation were as follows: 432.7 ± 24.5, 626.9 ± 49.2, 367.5 ± 25.1, and 379.9 ± 42.5 μM for M-1 and 336.7 ± 15.3, 494.3 ± 48.7, 211.4 ± 13.4, and 238.5 ± 26.2 μM for M-2, respectively. The PAL glucuronidation activity was significantly correlated with UGT1A6 activity rather than with UGT1A9 activity from 15 individual HLMs. A chemical inhibition study showed that the IC50 for phenylbutazone inhibition of PAL glucuronidation was similar in HLMs (61.9 ± 7.9 μM) compared with rUGT1A6 (45.3 ± 7.7 μM). In contrast, androsterone inhibited rUGT1A9-catalyzed and HLM-catalyzed PAL glucuronidation with IC50 values of 27.1 ± 3.8 and >500 μM, respectively. In combination, we identified UGT1A6 as the major isozyme responsible for PAL glucuronidation in HLMs.

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