Martínez-López Rosalía, Tuohy Maria G
School of Biological and Chemical Sciences, and Ryan Institute, National University of Ireland, Galway, Ireland.
Food Chem (Oxf). 2023 Feb 20;6:100166. doi: 10.1016/j.fochms.2023.100166. eCollection 2023 Jul 30.
Brown seaweeds () are a rich source of polyphenols (up to 20% dry weight) with a structure based on phloroglucinol (1,3,5-trihydroxybenzene). To-date the determination of total phenolics content (TPC) involves a redox reaction with the Folin-Ciocalteu (FC) reagent. However, side reactions with other reducing substances preclude accurate, direct measurement of TPC. This research reports a novel microplate assay involving a coupling reaction between phloroglucinol with Fast Blue BB (FBBB) diazonium salt, at basic pH, to form a stable tri-azo complex with maximum absorbance at 450 nm. Linear regression correlation values (R) were ≥0.99 with phloroglucinol as standard. Direct quantification of TPCs (phloroglucinol equivalents, PGEs) in crude aqueous and ethanolic extracts from demonstrated that the new FBBB assay is not subject to side-redox interference and provides a more accurate estimate of TPC (1.2-3.9-fold lower than with the FC assay) in a relatively rapid (30 min), cost-effective (0.24€/test) microplate format.
褐藻是多酚的丰富来源（高达干重的20%），其结构基于间苯三酚（1,3,5 - 三羟基苯）。迄今为止，总酚含量（TPC）的测定涉及与福林 - 西奥尔特试剂（FC）的氧化还原反应。然而，与其他还原物质的副反应妨碍了对TPC的准确、直接测量。本研究报告了一种新型微孔板测定法，该方法涉及在碱性pH条件下，间苯三酚与固蓝BB（FBBB）重氮盐之间的偶联反应，以形成在450nm处具有最大吸光度的稳定三偶氮配合物。以间苯三酚为标准品时，线性回归相关值（R）≥0.99。对来自[具体来源未给出]的粗水提取物和乙醇提取物中的TPC（间苯三酚当量，PGEs）进行直接定量分析表明，新的FBBB测定法不受副氧化还原干扰，并且以相对快速（30分钟）、经济高效（每次测试0.24欧元）的微孔板形式提供了对TPC更准确的估计（比FC测定法低1.2 - 3.9倍）。
