Abstract
Green (GT) and black tea (BT) polyphenols are metabolized to phenolic acids (PAs) by colonic microflora and may contribute to teas’ chemopreventive activity. The concentration of PAs was quantified in urine and serum from men drinking 6 cups daily of GT, BT or water by high performance liquid chromatography and electrochemical detection. 3,4‐dihydroxyphenyl acetic acid (3,4‐ DHPAA), 4‐hydroxyphenylacetic acid (4‐HPAA), 3‐ hydroxyphenylacetic acid (3‐HPAA), 3‐methoxy‐4‐ hydrozyphenylacetic acid (3M4‐HPAA) and hippuric acid were increased significantly in urine from men drinking GT. The consumption of BT was associated with a significant increase in urine 4‐HPAA and 3‐HPAA only. No significant changes were observed in serum. Fecal water contains a mixture of tea polyphenols such as epigallocatechin gallate (EGCG) and their PA metabolites. We therefore investigated the antiproliferative effect and intracellular concentration of EGCG, 3,4‐DHPAA and their methylated forms in HCT116 and HT‐29 colon cancer cells. Incubation with both EGCG and 3,4‐DHPAA exhibited an additive antiproliferative effect, while methylation of 3,4‐DHPAA was significantly decreased. In summary the consumption of GT was associated with a higher increase in urinary phenolic acids compared to BT. Combining EGCG with 3,4‐DHPAA enhanced the antiproliferative activity in colon cancer cells. Supported by RO1CA116242.
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