Tags

Type your tag names separated by a space and hit enter

Factors affecting the levels of tea polyphenols and caffeine in tea leaves.
J Agric Food Chem. 2003 Mar 26; 51(7):1864-73.JA

Abstract

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 microg/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.

Authors+Show Affiliations

Institute of Biochemistry, College of Medicine, National Taiwan University, Taipei, Taiwan.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

12643643

Citation

Lin, Yung-Sheng, et al. "Factors Affecting the Levels of Tea Polyphenols and Caffeine in Tea Leaves." Journal of Agricultural and Food Chemistry, vol. 51, no. 7, 2003, pp. 1864-73.
Lin YS, Tsai YJ, Tsay JS, et al. Factors affecting the levels of tea polyphenols and caffeine in tea leaves. J Agric Food Chem. 2003;51(7):1864-73.
Lin, Y. S., Tsai, Y. J., Tsay, J. S., & Lin, J. K. (2003). Factors affecting the levels of tea polyphenols and caffeine in tea leaves. Journal of Agricultural and Food Chemistry, 51(7), 1864-73.
Lin YS, et al. Factors Affecting the Levels of Tea Polyphenols and Caffeine in Tea Leaves. J Agric Food Chem. 2003 Mar 26;51(7):1864-73. PubMed PMID: 12643643.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Factors affecting the levels of tea polyphenols and caffeine in tea leaves. AU - Lin,Yung-Sheng, AU - Tsai,Yao-Jen, AU - Tsay,Jyh-Shyan, AU - Lin,Jen-Kun, PY - 2003/3/20/pubmed PY - 2003/5/8/medline PY - 2003/3/20/entrez SP - 1864 EP - 73 JF - Journal of agricultural and food chemistry JO - J. Agric. Food Chem. VL - 51 IS - 7 N2 - 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 microg/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. SN - 0021-8561 UR - https://www.unboundmedicine.com/medline/citation/12643643/Factors_affecting_the_levels_of_tea_polyphenols_and_caffeine_in_tea_leaves_ L2 - https://dx.doi.org/10.1021/jf021066b DB - PRIME DP - Unbound Medicine ER -