Determination of Theaflavins Including Methylated Theaflavins in Black Tea Leaves by Solid-Phase Extraction and HPLC Analysis

DOI Web Site PubMed 被引用文献12件
  • Masami Nishimura
    Division of Food Science & Nutrition, Nagoya Women's University, 3-40 Shioji-Cho Mizuho-ku, Nagoya 467-8610, Japan, and School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
  • Kinuko Ishiyama
    Division of Food Science & Nutrition, Nagoya Women's University, 3-40 Shioji-Cho Mizuho-ku, Nagoya 467-8610, Japan, and School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
  • Akiko Watanabe
    Division of Food Science & Nutrition, Nagoya Women's University, 3-40 Shioji-Cho Mizuho-ku, Nagoya 467-8610, Japan, and School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
  • Setsuko Kawano
    Division of Food Science & Nutrition, Nagoya Women's University, 3-40 Shioji-Cho Mizuho-ku, Nagoya 467-8610, Japan, and School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
  • Toshio Miyase
    Division of Food Science & Nutrition, Nagoya Women's University, 3-40 Shioji-Cho Mizuho-ku, Nagoya 467-8610, Japan, and School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
  • Mitsuaki Sano
    Division of Food Science & Nutrition, Nagoya Women's University, 3-40 Shioji-Cho Mizuho-ku, Nagoya 467-8610, Japan, and School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan

書誌事項

公開日
2007-08-15
DOI
  • 10.1021/jf070312m
公開者
American Chemical Society (ACS)

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A quantitative method for four theaflavins and two methylated theaflavin derivatives in black tea leaves was developed by solid-phase extraction and a high-performance liquid chromatographic method with photodiode array detection. The theaflavins in black tea leaves were extracted three times with 40 vol 50% aqueous ethanol (mg dry tea powder/mL) containing 2% ascorbic acid. The ethanol extracts were diluted 4-fold with distilled water. All diluted extracts were directly applied to the solid-phase C18 cartridge column without concentration. The fraction of theaflavins was obtained by 40% ethanol extraction after rinsing with water followed with 15% ethanol extraction. An aliquot of theaflavins after concentration was injected onto an ODS C18 reversed-phase column, and four theaflavins and two methylated theaflavins were sufficiently separated by a linear gradient system using distilled water and acetonitrile with 0.5% acetic acid. This analytical method is sensitive for the determination of a small amount of methylated theaflavins, since various interfering substances produced during the fermentation process were eliminated in advance by solid-phase extraction. Using this analytical method, we also demonstrated that methylated theaflavins were easily produced during the manufacture of black tea.

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