Gut microbiota contribute to the metabolism of dietary polyphenols and affect the bioavailability of both the parent polyphenols and their metabolites. Although there is a large number of reports of specific polyphenol metabolites, relatively little is known regarding the chemistry and enzymology of the metabolic pathways utilized by specific microbial species and taxa, which is the focus of this review. Major classes of dietary polyphenols include monomeric and oligomeric catechins (proanthocyanidins), flavonols, flavanones, ellagitannins, and isoflavones. Gut microbial metabolism of representatives of these polyphenol classes can be classified as A- and C-ring cleavage (retro Claisen reactions), C-ring cleavage mediated by dioxygenases, dehydroxylations (decarboxylation or reduction reactions followed by release of H2O molecules), and hydrogenations of alkene moieties in polyphenols, such as resveratrol, curcumin, and isoflavones (mediated by NADPH-dependent reductases). The qualitative and quantitative metabolic output of the gut microbiota depends to a large extent on the metabolic capacity of individual taxa, which emphasizes the need for assessment of functional analysis in conjunction with determinations of gut microbiota compositions.

中文翻译：

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多酚肠道微生物代谢的化学。

肠道菌群有助于饮食中多酚的代谢，并影响母体多酚及其代谢产物的生物利用度。尽管有大量关于特定多酚代谢产物的报道，但是关于特定微生物物种和生物分类群利用的代谢途径的化学和酶学知识知之甚少，这是本综述的重点。膳食多酚的主要类别包括单体和低聚儿茶素（原花青素），黄酮醇，黄烷酮，鞣花单宁和异黄酮。这些多酚类代表的肠道微生物代谢可分为A环和C环裂解（复古克莱森反应），双加氧酶介导的C环裂解，脱羟基（脱羧或还原反应，然后释放H2O分子），和多酚（例如白藜芦醇，姜黄素和异黄酮）中烯烃部分的氢化（由NADPH依赖性还原酶介导）。肠道菌群的定性和定量代谢产物在很大程度上取决于单个分类单元的代谢能力，这强调了结合肠道菌群组成测定来评估功能分析的必要性。