PMID: 11922115Apr 2, 2002Paper

Analytical method of measuring tea catechins in human plasma by solid-phase extraction and HPLC with electrochemical detection

Journal of Nutritional Science and Vitaminology
K UmegakiM Higuchi

Abstract

We developed an analytical method for measuring tea catechins in plasma by solid-phase extraction (SPE), followed by HPLC with a coulometric electrochemical detector. The plasma was mixed with an equal volume of acetonitrile to precipitate protein, and catechins in the resulting supernatant were extracted by SPE, using a C18 cartridge. To correct the extraction efficiency, ethyl gallate was simultaneously added with acetonitrile as an internal standard. Plasma samples were treated in microtubes, and evaporation and SPE were performed by the use of a vacuum centrifuge and vacuum manifold for SPE. The use of these instruments allowed the handling of a large number of samples simultaneously. In this method, (-)-epicatechin (EC), (-)-epicatechin-3-O-gallate (ECg), (-)-epigallocatechin (EGC), (-)-epigallocatechin-3-O-gallate (EGCg), and ethyl gallate could be detected as a single peak with high sensitivity. For an analysis of the conjugated form of catechins, plasma samples were treated with glucuronidase and sulfatase. Type H-2 beta-glucuronidase effectively digested the conjugated forms, and the enzyme also converted EGCg and ECg to their nongallated form. When the concentrations of catechins in plasma were analyzed in subjects wh...Continue Reading

Citations

Sep 30, 2005·Journal of the American College of Nutrition·Reiko Hirano-OhmoriFumitaka Ohsuzu
May 8, 2010·Arthritis Research & Therapy·Salahuddin Ahmed
Feb 14, 2007·Analytical Sciences : the International Journal of the Japan Society for Analytical Chemistry·Akira KotaniFumiyo Kusu
Oct 17, 2014·Journal of Clinical Biochemistry and Nutrition·Kanako MatsuuraTsutomu Nakayama
Jun 7, 2016·Journal of Nutritional Science and Vitaminology·Keizo UmegakiMasaru Sonoda
Dec 19, 2016·International Journal of Pharmaceutics·Nisha TyagiAmirali Popat
Jun 7, 2017·Journal of Alzheimer's Disease : JAD·Warnakulasuriya M A D B FernandoRalph N Martins
Jul 3, 2021·Antioxidants·Nicoleta Bianca TudorachiElena Mihaela Cărăuşu
Dec 22, 2005·Journal of Agricultural and Food Chemistry·Tomonori UnnoTakami Kakuda
Oct 2, 2007·Journal of Agricultural and Food Chemistry·Maria de Lourdes Mata-BilbaoRosa Maria Lamuela-Raventós
Sep 30, 2021·Journal of the European Academy of Dermatology and Venereology : JEADV·C BraegelmannJ Wenzel

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