Turmeric and curcumin modulate the conjugation of 1-naphthol in caco-2 cells

Megumi Naganuma, Ayako Saruwatari, Shigeaki Okamura, Hiroomi Tamura

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Turmeric, the powdered dry rhizome of the Curcuma longa plant, and curcumin, the major anti-oxidant constituent of turmeric, have been shown to possess chemopreventive activity. To elucidate the possible interaction of turmeric and curcumin with conjugation reactions, which in many cases are involved in the activation of procarcinogens, we measured their effects in the conjugation of 1-naphthol in Caco-2 cells, a human colon carcinoma cell line, within a 24 h period. Turmeric exhibits inhibitory activity toward both sulfo- and glucuronosyl conjugations of 1-naphthol at approximately the same levels (IC50=0.24 and 0.29 mg/ml, respectively). Curcumin inhibits sulfo-conjugation at lower concentrations (IC50=9.7 μg/ml), but only showed weak inhibition toward glucuronosyl conjugation of 1-naphthol in Caco-2 cells. In addition, turmeric was found to strongly inhibit in vitro phenol sulfotransferase (SULT) activity and demonstrate moderate inhibitory properties against UDP-glucuronosyl transferase (UGT) activity in Caco-2 cells (IC50=0.17 mg/ml and 0.62 mg/ml, respectively). Curcumin also strongly inhibits in vitro phenol sulfotransferase activity with an IC 50 of 2.4 μg/ml. Moreover, and in contrast to the moderate inhibition of UGT activity by turmeric and curcumin, both induce the expression of the UGT1A1 and UGT1A6 genes, revealed by real-time PCR analysis. These findings are indicative of a possible interaction of both turmeric and curcumin with conjugation reactions in the human intestinal tract and colon. This in turn may affect the bioavailability of therapeutic drugs and toxicity levels of environmental chemicals, particularly procarcinogens.

Original languageEnglish
Pages (from-to)1476-1479
Number of pages4
JournalBiological and Pharmaceutical Bulletin
Volume29
Issue number7
DOIs
Publication statusPublished - 2006 Jul 12

Keywords

  • Caco-2
  • Conjugation
  • Curcumin
  • Sulfotransferase (SULT)
  • Turmeric
  • UDP-glucuronosyl transferase (UGT)

ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science

Fingerprint Dive into the research topics of 'Turmeric and curcumin modulate the conjugation of 1-naphthol in caco-2 cells'. Together they form a unique fingerprint.

  • Cite this