School of Food Science and Nutrition, University of Leeds, Leeds, UK.
Br J Nutr. 2010 Oct;104 Suppl 3:S48-66. doi: 10.1017/S0007114510003946.
The absorption of dietary phenols, polyphenols and tannins (PPT) is an essential step for biological activity and effects on health. Although a proportion of these dietary bioactive compounds are absorbed intact, depending on their chemical structure and the nature of any attached moiety (e.g. sugar, organic acid), substantial amounts of lower molecular weight catabolites are absorbed after biotransformation by the colon microflora. The main products in the colon are (a) benzoic acids (C6-C1), especially benzoic acid and protocatechuic acid; (b) phenylacetic acids (C6-C2), especially phenylacetic acid per se; (c) phenylpropionic acids (C6-C3), where the latter are almost entirely in the dihydro form, notably dihydrocaffeic acid, dihydroferulic acid, phenylpropionic acid and 3-(3'-hydroxyphenyl)-propionic acid. As a result of this biotransformation, some of these compounds can each reach mm concentrations in faecal water. Many of these catabolites are efficiently absorbed in the colon, appear in the blood and are ultimately excreted in the urine. In the case of certain polyphenols, such as anthocyanins, these catabolites are major products in vivo; protocatechuic acid is reported to represent a substantial amount of the ingested dose of cyanidin-3-O-glucoside. The major catabolites of berries, and especially blackcurrants, are predicted based on compositional data for polyphenols from berries and other sources. Since microbial catabolites may be present at many sites of the body in higher concentration than the parent compound, it is proposed that at least a part of the biological activities ascribed to berry polyphenols and other PPT are due to their colonic catabolites.
膳食酚类、多酚和单宁（PPT）的吸收是其发挥生物活性和对健康产生影响的必要步骤。尽管这些饮食生物活性化合物中有一部分完整吸收，但取决于其化学结构和任何附着部分的性质（例如糖、有机酸），大量的低分子量代谢物在结肠微生物群的生物转化后被吸收。结肠中的主要产物为：（a）苯甲酸（C6-C1），特别是苯甲酸和原儿茶酸；（b）苯乙酸（C6-C2），特别是苯乙酸本身；（c）苯丙酸（C6-C3），其中后者几乎全部以二氢形式存在，主要有二咖啡酸、二阿魏酸、苯丙酸和 3-（3'-羟基苯基）-丙酸。由于这种生物转化，这些化合物中的一些可以达到粪便水中的 mm 浓度。这些代谢物中的许多都能在结肠中被高效吸收，出现在血液中，并最终从尿液中排出。对于某些多酚，如花青素，这些代谢物是体内的主要产物；据报道，原儿茶酸代表摄入的矢车菊素-3-O-葡萄糖苷剂量的很大一部分。浆果，尤其是黑加仑的主要代谢物是基于浆果和其他来源的多酚的组成数据预测的。由于微生物代谢物可能在身体的许多部位以高于母体化合物的浓度存在，因此有人提出，至少一部分归因于浆果多酚和其他 PPT 的生物活性是由于其结肠代谢物所致。
