Gorecka Aleksandra, Schacht Heidi, Fraser Megan K, Teriosina Aleksandra, London James A, Barsukov Igor L, Powell Andrew K, Cartmell Alan, Stachulski Andrew V, Yates Edwin A
Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Crown Street, Liverpool L69 7ZB, U.K.
ACS Omega. 2024 Dec 20;10(1):1419-1428. doi: 10.1021/acsomega.4c09036. eCollection 2025 Jan 14.
The human gut microbiota (HGM) is a complex ecosystem subtly dependent on the interplay between hundreds of bacterial species and numerous metabolites. Dietary phenols, whether ingested (e.g., plant-derived guaiacol, mequinol, or resveratrol) or products of bacterial fermentation (e.g., -cresol), have been attributed with influencing bacterial growth and host health. They are cleared by phase II metabolism, one form utilizing β-d-glucuronidation, but encounter bacterially derived glucuronidases capable of hydrolyzing them to release their phenolic and glucuronic acid moieties with potential effects on host cells or the surrounding bacterial population. Tools to enable the detailed study of their activity are currently lacking. Syntheses of β-d-glucuronides from methyl 1,2,3,4 tetra-acetyl β-d-glucopyranosyluronate by direct glycosylation with 2-, 3-, or 4-methoxy- and 4-fluorophenol acceptors employing trimethylsilyl triflate catalysis are reported. Yields (methoxy series) were modest. An improved route from methyl 1,2,3,4-tetra-acetyl β-d-glucopyranosyluronate via selective anomeric deprotection (-methyl piperazine) and conversion to an α-trichloroacetimidate glycosyl donor was employed. Coupling with 2- and 3-methoxyphenol acceptors and deprotection provided 2- and 3-methoxyphenyl β-d-glucuronides in 2-fold improved overall yield. These naturally occurring methoxyphenyl glucuronides augment available model substrates of dietary glucuronides, which include 3- and 4'-linked resveratrol. The use of model glucuronides as substrates was illustrated in studies of β-d-glucuronidase activity employing cell lysates of 9 species of HGM (), revealing distinct outcomes. Contrasting effects on bacterial growth were also observed between the free phenolic components, their respective glucuronides, and glucuronic acid. The glucuronide of 4-fluorophenol provided sensitive and background-free detection of β-glucuronidase activity using F NMR.
人类肠道微生物群（HGM）是一个复杂的生态系统，微妙地依赖于数百种细菌物种和众多代谢物之间的相互作用。膳食酚类物质，无论是摄入的（如植物来源的愈创木酚、甲萘醌或白藜芦醇）还是细菌发酵产物（如对甲酚），都被认为会影响细菌生长和宿主健康。它们通过II相代谢清除，一种形式是利用β-d-葡萄糖醛酸化，但会遇到细菌来源的葡萄糖醛酸酶，这些酶能够水解它们，释放出酚类和葡萄糖醛酸部分，对宿主细胞或周围细菌群体产生潜在影响。目前缺乏能够详细研究其活性的工具。报道了通过三甲基甲硅烷基三氟甲磺酸酯催化，将1,2,3,4-四乙酰基-β-d-吡喃葡萄糖醛酸甲酯与2-、3-或4-甲氧基苯酚受体以及4-氟苯酚受体直接糖基化合成β-d-葡萄糖醛酸苷。产率（甲氧基系列）一般。采用了一条改进的路线，从1,2,3,4-四乙酰基-β-d-吡喃葡萄糖醛酸甲酯出发，通过选择性异头脱保护（-甲基哌嗪）并转化为α-三氯乙酰亚胺糖基供体。与2-和3-甲氧基苯酚受体偶联并脱保护，得到2-和3-甲氧基苯基-β-d-葡萄糖醛酸苷，总产率提高了2倍。这些天然存在的甲氧基苯基葡萄糖醛酸苷增加了膳食葡萄糖醛酸苷可用的模型底物，其中包括3-和4'-连接的白藜芦醇。在使用9种HGM（）细胞裂解物研究β-d-葡萄糖醛酸酶活性的过程中，展示了使用模型葡萄糖醛酸苷作为底物的情况，揭示了不同的结果。在游离酚类成分及其各自的葡萄糖醛酸苷和葡萄糖醛酸之间，也观察到了对细菌生长的不同影响。4-氟苯酚的葡萄糖醛酸苷通过19F NMR提供了对β-葡萄糖醛酸酶活性的灵敏且无背景的检测。
