Stability, cellular uptake, biotransformation, and efflux of tea polyphenol (-)-epigallocatechin-3-gallate in HT-29 human colon adenocarcinoma cells

Jungil Hong, Hong Lu, Xiaofeng Meng, Jae Ha Ryu, Yukihiko Hara, Chung S. Yang

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338 Scopus citations

Abstract

The biological effects of (-)-epigallocatechin-3-gallate (EGCG) have been extensively investigated in cell lines, but its stability and interactions with cells under culture conditions are unclear. In the present study, the stability, uptake, biotransformation, and efflux of [3H]EGCG in HT-29 human colon adenocarcinoma cells were investigated. EGCG was unstable in McCoy's 5A culture media with a half-life of less than 30 min, and the half-life increased to 130 min in the presence of cells. The major oxidative products were theasinensin (Mr 914) and another dimer with Mr 884. Addition of EGCG (50 μM) to cell culture media caused the production of H2O2 (up to 25 μM), and the amount was lower and gradually decreased in the presence of cells. The uptake of EGCG was concentration dependent and did not plateau, even at 640 μM, suggesting a passive diffusion process. Approximately 75% of the [3H]EGCG was found in the cytoplasmic fraction when the cells were incubated with 0.5-20 μM [3H]EGCG for 15 min. The membrane-associated radioactivity increased with time, apparently because of the binding of dimers to the membrane. The accumulation of [3H]EGCG in the cells was significantly higher at 4°C than at 37°C. Multidrug-resistant protein inhibitors, such as indomethacin and probenecid, effectively increased the accumulation of EGCG 4″-glucuronide and 4″-methyl EGCG in the cell. These results suggest that EGCG is metabolized in the cell and that the metabolites are pumped out by MRPs. The present study provides fundamental information on the stability, uptake, biotransformation, and efflux of EGCG under cell culture conditions and suggests the need for careful interpretation of related results on the biological activities of EGCG.

Original languageEnglish (US)
Pages (from-to)7241-7246
Number of pages6
JournalCancer Research
Volume62
Issue number24
StatePublished - Dec 15 2002

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

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