The fate of olive oil polyphenols in the gastrointestinal tract: Implications of gastric and colonic microflora-dependent biotransformation |
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| Authors: | Giulia Corona Xenofon Tzounis M. Assunta DessÌ Monica Deiana Edward S. Debnam Francesco Visioli |
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| Affiliation: | 1. Sez. Patologia Sperimentale, Università degli Studi di Cagliari, Dipartimento di Biologia Sperimentale, Monserrato, 09042, Italy;2. Molecular Nutrition Group, School of Food Biosciences, University of Reading, Reading, RG6 6AP, UK;3. Royal Free and University College Medical School, Department of Physiology, London, UK;4. Department of Pharmacological Sciences, University of Milan, Milan, 20133, Italy |
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| Abstract: | We have conducted a detailed investigation into the absorption, metabolism and microflora-dependent transformation of hydroxytyrosol (HT), tyrosol (TYR) and their conjugated forms, such as oleuropein (OL). Conjugated forms underwent rapid hydrolysis under gastric conditions, resulting in significant increases in the amount of free HT and TYR entering the small intestine. Both HT and TYR transferred across human Caco-2 cell monolayers and rat segments of jejunum and ileum and were subject to classic phase I/II biotransformation. The major metabolites identified were an O-methylated derivative of HT, glucuronides of HT and TYR and a novel glutathionylated conjugate of HT. In contrast, there was no absorption of OL in either model. However, OL was rapidly degraded by the colonic microflora resulting in the formation of HT. Our study provides additional information regarding the breakdown of complex olive oil polyphenols in the GI tract, in particular the stomach and the large intestine. |
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| Keywords: | Olive oil hydroxytyrosol tyrosol absorption metabolism colonic microflora |
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