chlorophyll-a and epigallocatechin-gallate

Topics: Anticarcinogenic Agents; Antimutagenic Agents; Carcinogenicity Tests; Catechin; Chlorophyll; Diet; Hemin; Humans; Mutagenicity Tests; Neoplasms; Risk Factors

Fresh tea leaves (Camellia sinensis; Chuanxiaoye) used to make tencha tea are a combination of the stem and leaf. Tencha made from the leaf alone is considered a high-quality tencha beverage with a seaweed-like aroma, mellow taste, and a green appearance. However, no study has investigated the differences between these two variants. In this study, the effects of stem removal on physicochemical properties and sensory quality of tencha beverage were investigated. The appearance feature, taste, and aroma were evaluated, and the results indicated that stem removal improved the quality of tencha beverages. The water extract, total free amino acids, total catechin, epigallocatechin gallate, caffeine, and chlorophyll were higher in leaf-only tencha (LOT) than in leaf and stem tencha (LST), whereas the crude fiber and phenol ammonia ratios were lower in LOT than in LST. Principal component analysis and hierarchical clustering analysis further discriminated between the tencha beverages with different stem contents. This study provided a theoretical basis for quality control by adopting a stem-leaf separation process in tencha manufacturing. PRACTICAL APPLICATION: This research provides theoretical guidance for improving tencha quality during manufacturing.

Topics: Beverages; Caffeine; Camellia sinensis; Catechin; Chemical Phenomena; Chlorophyll; Odorants; Phenols; Plant Leaves; Plant Stems; Quality Control; Sensation; Taste; Tea

Albino tea cultivars are special mutants of tea plants with white or yellow leaf color. In this study, three albino tea cultivars, including 'Anji Baicha', 'Huangjinya', and 'Baijiguan', and two green tea cultivars, 'Longjing 43' and 'Fuding Dabaicha', were applied to metabolite profiling by gas chromatography-mass spectrometry and ultraperformance liquid chromatography-mass spectrometry. Multivariate analyses revealed significantly different metabolite phenotypes in leaves among albino cultivars and green cultivars. The differential metabolite-related pathways included galactose metabolism, tryptophan metabolism, phenylpropanoid biosynthesis, and flavonoid biosynthesis. For the young leaves of albino cultivars, the sugar (sorbitol and erythrose) and amino acid (mainly proline, isoleucine, ornithine, aspartic acid, threonine, and valine) concentrations increased, whereas gallocatechin and epigallocatechin gallate concentrations decreased. These results reveal the divergence in metabolic profiling between tea plant cultivars with different leaf colors. With the development of leaves, the concentrations of flavonoids increased largely in the older leaves of albino cultivars.

Topics: Amino Acids; Camellia sinensis; Catechin; Chlorophyll; Gas Chromatography-Mass Spectrometry; Plant Extracts; Plant Leaves; Sugars

Environmental contaminants such as dioxins enter the body mainly through diet and cause various toxicities through transformation of the aryl hydrocarbon receptor (AhR). We previously reported that certain natural flavonoids at the dietary level suppress the AhR transformation induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In this study, we identified lutein and chlorophyll a and b from green tea leaves as the novel antagonists for AhR. These active compounds suppressed AhR transformation dose-dependently with the 50% inhibitory concentration (IC(50)) values against 0.1 nM TCDD-induced AhR transformation at 3.2, 5.0, and 5.9 microM, respectively. (-)-Epigallocatechin gallate, which is the most abundant flavonoid in green tea leaves, also showed stronger suppressive effects than did other major tea components, with the IC(50) value of 1.7 microM. Thus, these pigments of green tea leaves have the potential to protect from dioxin toxicity through the suppression of AhR transformation.

Topics: Camellia sinensis; Catechin; Chlorophyll; Flavonoids; Lutein; Phenols; Pigments, Biological; Plant Extracts; Plant Leaves; Polychlorinated Dibenzodioxins; Polyphenols; Receptors, Aryl Hydrocarbon