Factors Affecting the Levels of Tea Polyphenols and Caffeine in Tea Leaves

• Published in: Journal of agricultural and food chemistry Vol. 51; no. 7; pp. 1864 - 1873
• Main Authors: Lin, Yung-Sheng, Tsai, Yao-Jen, Tsay, Jyh-Shyan, Lin, Jen-Kun
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 26.03.2003
• Subjects: apoptosis; Biological and medical sciences; black tea; caffeine; Caffeine - analysis; Camellia sinensis - chemistry; Catechin - analogs & derivatives; Catechin - analysis; Chromatography, High Pressure Liquid; Coffee, tea and other stimulative beverage industries; DNA; DNA fragmentation; ethanol; fermentation; flavanols; Flavonoids; flow cytometry; Food industries; Free Radical Scavengers - pharmacology; Fundamental and applied biological sciences. Psychology; General pharmacology; green tea; high performance liquid chromatography; Hot Temperature; Hydroxyl Radical; leaves; Medical sciences; nitric oxide; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Phenols - analysis; Plant Extracts - pharmacology; Plant Leaves - chemistry; Polymers - analysis; polyphenols; Tea - chemistry; Catechin; catechins; tea leaves; Stimulative beverage; Plant leaf; Antioxidant; hydroxyl radical scavenging; Tea; Polyphenol; nitric oxide suppressing; Nitric oxide; tea polyphenols; Quantitative analysis; Apoptosis; Caffeine
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf021066b

An isocratic HPLC procedure was developed for the simultaneous determination of caffeine and six catechins in tea samples. When 31 commercial teas extracted by boiling water or 75% ethanol were analyzed by HPLC, the levels of (−)-epigallocatechin 3-gallate (EGCG), and total catechins in teas were in the order green tea (old leaves) > green tea (young leaves) and oolong tea > black tea and pu-erh tea. Tea samples extracted by 75% ethanol could yield higher levels of EGCG and total catechins. The contents of caffeine and catechins also have been measured in fresh tea leaves from the Tea Experiment Station in Wen-Shan or Taitung; the old tea leaves contain less caffeine but more EGCG and total catechins than young ones. To compare caffeine and catechins in the same tea but manufactured by different fermentation processes, the level of caffeine in different manufactured teas was in the order black tea > oolong tea > green tea > fresh tea leaf, but the levels of EGCG and total catechins were in the order green tea > oolong tea > fresh tea leaf > black tea. In addition, six commercial tea extracts were used to test the biological functions including hydroxyl radical scavenging, nitric oxide suppressing, and apoptotic effects. The pu-erh tea extracts protected the plasmid DNA from damage by the Fenton reaction as well as the control at a concentration of 100 μg/mL. The nitric oxide suppressing effect of tea extracts was in the order pu-erh tea ≥ black tea > green tea > oolong tea. The induction of apoptosis by tea extract has been demonstrated by DNA fragmentation ladder and flow cytometry. It appeared that the ability of tea extracts to induce HL-60 cells apoptosis was in the order green tea > oolong > black tea > pu-erh tea. All tea extracts extracted by 75% ethanol have stronger biological functions than those extracted by boiling water. Keywords: Tea; tea leaves; catechins; tea polyphenols; caffeine; apoptosis; hydroxyl radical scavenging; nitric oxide suppressing