Categories
BLOG

potent tea

Potent antimutagenic activity of white tea in comparison with green tea in the Salmonella assay

Affiliation

  • 1 Linus Pauling Institute, Department of Environmental and Molecular Toxicology, Oregon State University, 571 Weniger HallCorvallis, OR 97331-6512, USA.
  • PMID: 11448643
  • DOI: 10.1016/s1383-5718(01)00200-5

Potent antimutagenic activity of white tea in comparison with green tea in the Salmonella assay

  • Search in PubMed
  • Search in NLM Catalog
  • Add to Search

Authors

Affiliation

  • 1 Linus Pauling Institute, Department of Environmental and Molecular Toxicology, Oregon State University, 571 Weniger HallCorvallis, OR 97331-6512, USA.
  • PMID: 11448643
  • DOI: 10.1016/s1383-5718(01)00200-5

Abstract

There is growing interest in the potential health benefits of tea, including the antimutagenic properties. Four varieties of white tea, which represent the least processed form of tea, were shown to have marked antimutagenic activity in the Salmonella assay, particularly in the presence of S9. The most active of these teas, Exotica China white tea, was significantly more effective than Premium green tea (Dragonwell special grade) against 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and four other heterocyclic amine mutagens, namely 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). Mechanism studies were performed using rat liver S9 in assays for methoxyresorufin O-demethylase (MROD), a marker for the enzyme cytochrome P4501A2 that activates heterocyclic amines, as well as Salmonella assays with the direct-acting mutagen 2-hydroxyamino-3-methylimidazo[4,5-f]quinoline (N-hydroxy-IQ). White tea at low concentrations in the assay inhibited MROD activity, and attenuated the mutagenic activity of N-hydroxy-IQ in the absence of S9. Nine of the major constituents found in green tea also were detected in white tea, including high levels of epigallocatechin-3-gallate (EGCG) and several other polyphenols. When these major constituents were mixed to produce “artificial” teas, according to their relative levels in white and green teas, the complete tea exhibited higher antimutagenic potency compared with the corresponding artificial tea. The results suggest that the greater inhibitory potency of white versus green tea in the Salmonella assay might be related to the relative levels of the nine major constituents, perhaps acting synergistically with other (minor) constituents, to inhibit mutagen activation as well as “scavenging” the reactive intermediate(s).

There is growing interest in the potential health benefits of tea, including the antimutagenic properties. Four varieties of white tea, which represent the least processed form of tea, were shown to have marked antimutagenic activity in the Salmonella assay, particularly in the presence of S9. The m …

Identification of potent odorants in different green tea varieties using flavor dilution technique

Affiliation

  • 1 Material Research and Development Laboratories, Ogawa & Company, Ltd., 15-7 Chidori Urayasushi, Chiba 279-0032, Japan.
  • PMID: 12236694
  • DOI: 10.1021/jf020498j

Identification of potent odorants in different green tea varieties using flavor dilution technique

  • Search in PubMed
  • Search in NLM Catalog
  • Add to Search

Authors

Affiliation

  • 1 Material Research and Development Laboratories, Ogawa & Company, Ltd., 15-7 Chidori Urayasushi, Chiba 279-0032, Japan.
  • PMID: 12236694
  • DOI: 10.1021/jf020498j

Abstract

Two kinds of pan-fired green teas (Japanese Kamairi-cha and Chinese Longing tea) were compared with the common Japanese green tea (Sen-cha). Application of the aroma extract dilution analysis (AEDA) using the volatile fraction of the Sen-cha, Kamairi-cha and Longing tea infusions revealed 32, 51, and 52 odor-active peaks with flavor dilution factors between 16 and 1024, respectively. (Z)-1,5-Octadien-3-one (metallic, geranium-like), 4-mercapto-4-methyl-2-pentanone (meaty, black currant-like), methional (potato-like), (E,Z)-2,6-nonadienal (cucumber-like), and 3-methylnonane-2,4-dione (green, fruity, hay-like) showed high flavor dilution factors in all varieties. In addition, 2-acetyl-1-pyrroline (popcorn-like), 2-ethyl-3,5-dimethylpyrazine (nutty), 2,3-diethyl-5-methylpyrazine (nutty), and 2-acetyl-2-thiazoline (popcorn-like) belonged to the most potent odorants only in the pan-fired green teas. Among these odorants, 2-acetyl-1-pyrroline and 2-acetyl-2-thiazoline were identified for the first time among the tea volatiles.

Two kinds of pan-fired green teas (Japanese Kamairi-cha and Chinese Longing tea) were compared with the common Japanese green tea (Sen-cha). Application of the aroma extract dilution analysis (AEDA) using the volatile fraction of the Sen-cha, Kamairi-cha and Longing tea infusions revealed 32, 51, an …