Green tea polyphenols modify gut-microbiota dependent metabolisms of energy, bile constituents and micronutrients in female Sprague-Dawley rats

Our recent metagenomics analysis has uncovered remarkable modifying effects of green tea polyphenols (GTP) on gut-microbiota community structure and energy conversion related gene orthologs in rats. How these genomic changes could further influence host health is still unclear. In this work, the alterations of gut-microbiota dependent metabolites were studied in the GTP-treated rats. Six groups of female SD rats (n=12/group) were administered drinking water containing 0%, 0.5%, and 1.5% GTP (wt/vol). Their gut contents were collected at 3 and 6 months and were analyzed via high performance liquid chromatography (HPLC) and gas chromatography (GC)-mass spectrometry (MS). GC-MS based metabolomics analysis captured 2668 feature, and 57 metabolites were imputatively from top 200 differential features identified via NISI fragmentation database. A group of key metabolites were quantitated using standard calibration methods. Compared with control, the elevated components in the GTP-treated groups include niacin (8.61-fold), 3-phenyllactic acid (2.20-fold), galactose (3.13-fold), mannose (2.05-fold), pentadecanoic add (2.15-fold), lactic acid (2.70-fold), and proline (2.15-fold); the reduced components include cholesterol (0.29-fold), cholic acid (0.62-fold), deoxycholic add (0.41-fold), trehalose (0.14-fold), glucose (0.46-fold), fructose (0.12-fold), and alanine (0.61-fold). These results were in line with the genomic alterations of gut-microbiome previously discovered by metagenomics analysis. The alterations of these metabolites suggested the reduction of calorific carbohydrates, elevation of vitamin production, decreases of bile constituents, and modified metabolic pattern of amino acids in the GTP-treated animals. Changes in gut-microbiota associated metabolism may be a major contributor to the anti-obesity function of GTP. (C) 2018 Elsevier Inc. All rights reserved.