Urolithins (dibenzo-pyran-[b,d]-6 one derivatives) are human gut microbiota metabolites produced from the natural food antioxidant ellagic acid. Urolithins are better absorbed than ellagic acid and demonstrate biological activities that suggest that they are responsible for the health effects observed after consuming ellagitannin- and ellagic acid-containing foods. Urolithins occur in the systemic circulation as glucuronide conjugates following phase II metabolism. These phase II conjugates are essential for testing the urolithin mechanisms of action in human cell line bioassays. Urolithin glucuronides are not commercially available, and their biosynthesis leads to mixtures of regional isomers. This study describes a novel and regioselective synthesis of urolithin A (3,8-dihydroxy urolithin) 3- and 8-glucuronides and isourolithin A (3,9-dihydroxy urolithin) 3- and 9-glucuronides. The metabolites were characterized using ¹H and ¹³C NMR spectroscopy and UV spectrophotometry. The presence of these metabolites in human subjects belonging to different urolithin metabotypes was also investigated.

中文翻译：

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尿石素葡萄糖苷酸的新型区域选择性合成─鞣花单宁和鞣花酸的人体肠道微生物群代谢产物

尿石素 (dibenzo-pyran-[ b , d]-6 一种衍生物）是由天然食品抗氧化剂鞣花酸产生的人体肠道微生物群代谢产物。尿石素比鞣花酸更容易被吸收，并显示出生物活性，这表明它们是食用含有鞣花单宁和鞣花酸的食物后观察到的健康影响的原因。在 II 期代谢后，尿石素作为葡糖苷酸结合物出现在体循环中。这些 II 期偶联物对于测试人类细胞系生物测定中的尿石素作用机制至关重要。尿石素葡糖苷酸不能从市场上买到，它们的生物合成会导致区域异构体的混合物。本研究描述了尿石素 A (3,8-二羟基尿石素) 3-和 8-葡糖苷酸和异尿石素 A (3, 9-二羟基尿石素）3-和9-葡糖苷酸。代谢物的特征是使用¹ H 和¹³ C NMR 光谱和紫外分光光度法。还研究了这些代谢物在属于不同尿石素代谢型的人类受试者中的存在。