title: Simultaneous detection of green tea catechins and gallic acid in human serum after ingestion of green tea tablets using ion-pair high-performance liquid chromatography with electrochemical detection.
abstract: We developed an analytical method for the simultaneous determination of tea catechins and gallic acid (GA) in human serum using ion-pair high-performance liquid chromatography (HPLC) with electrochemical detection. GA was measured to estimate the amount of gallate moiety produced by degradation of gallated catechins ((-)-epicatechin-3-gallate, ECG; (-)-epigallocatechin-3-gallate, EGCG). Ethyl gallate was adopted as an internal standard to correct for the extraction efficiency. To maximize extraction efficiency, a hydrophobic polytetrafluoroethylene (PTFE) filter was selected for pre-treatment prior to separation. HPLC separation was performed using a C18 reversed-phase column with a gradient mobile phase of phosphate buffer (pH 2.5) containing tetrahexylammonium hydrogensulfate as an ion-pair reagent. Using this method, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), ECG, EGCG, ethyl gallate, and GA were detected as single peaks. The resolution values for target analytes were 4.0-13.0 and the mean values of the absolute recoveries of catechins and GA were 77.3-93.9%. The detection limits for catechins and GA in serum were 0.4-3.1ng/mL. The serum catechin levels of eight healthy volunteers after ingestion of a single dose of green tea tablets were measured using this method. The concentration of total catechins (free+conjugated forms) in serum peaked 60min after ingestion. From these results, this method is thought to enable the simultaneous quantification of GA, the hydrolysis product of gallated catechins, and target catechins, and to be sufficiently sensitive for pharmacokinetic studies of catechins following oral administration of green tea.
authors.affiliation: First Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kyushu University of Health & Welfare, 1714-1 Yoshino-cho, Nobeoka, Miyazaki 882-8508, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Narumi
authors.affiliation: First Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kyushu University of Health & Welfare, 1714-1 Yoshino-cho, Nobeoka, Miyazaki 882-8508, Japan. Electronic address: son@phoenix.ac.jp.
authors.forename: Jun-Ichiro
authors.initials: J
authors.lastname: Sonoda
authors.affiliation: First Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kyushu University of Health & Welfare, 1714-1 Yoshino-cho, Nobeoka, Miyazaki 882-8508, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Shiotani
authors.affiliation: First Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kyushu University of Health & Welfare, 1714-1 Yoshino-cho, Nobeoka, Miyazaki 882-8508, Japan.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Shigeru
authors.affiliation: First Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kyushu University of Health & Welfare, 1714-1 Yoshino-cho, Nobeoka, Miyazaki 882-8508, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Shibata
authors.affiliation: First Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kyushu University of Health & Welfare, 1714-1 Yoshino-cho, Nobeoka, Miyazaki 882-8508, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Kawachi
authors.affiliation: First Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kyushu University of Health & Welfare, 1714-1 Yoshino-cho, Nobeoka, Miyazaki 882-8508, Japan.
authors.forename: Erisa
authors.initials: E
authors.lastname: Tomishige
authors.affiliation: Department of Clinical Biochemistry, School of Pharmaceutical Sciences, Kyushu University of Health & Welfare, 1714-1 Yoshino-cho, Nobeoka, Miyazaki 882-8508, Japan.
authors.forename: Keizo
authors.initials: K
authors.lastname: Sato
authors.affiliation: First Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kyushu University of Health & Welfare, 1714-1 Yoshino-cho, Nobeoka, Miyazaki 882-8508, Japan.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Motoya
mesh_terms: D000284:Administration, Oral; D000328:Adult; D002392:Catechin / Q000031:analogs & derivatives* / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D055664:Electrochemical Techniques; D005260:Female; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D013607:Tablets; D013662:Tea / Q000737:chemistry; D055815:Young Adult
chemical_list: D013607:Tablets; D013662:Tea; C048734:ethyl gallate; D005707:Gallic Acid; D002392:Catechin; C062669:epicatechin gallate; C045651:epigallocatechin gallate
keywords: Electrochemical detection; Gallic acid; Green tea catechins; HPLC; Ion-pair reagent; Pharmacokinetic study