Key Laboratory of Tea Biology and Resource Utilization of Ministry of Agriculture, Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China.
Key Laboratory of Tea Biology and Resource Utilization of Ministry of Agriculture, Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China.
Food Res Int. 2017 Oct;100(Pt 3):486-493. doi: 10.1016/j.foodres.2016.10.024. Epub 2016 Oct 15.
Dark teas are rich in secondary metabolites, such as phenolics and flavonoids, which have been suggested to be associated with their health benefits. In this study, the concentrations of tea polyphenols, tea pigments, catechins, flavonoids, alkaloid, and volatile components in 44 dark tea samples, including Pu-erh, Fuzhuan and Liubao teas, were systematically examined. Among the samples tested, Pu-erh tea contained the highest total flavonoid content (5.24±0.05%), followed by Liubao (4.45±0.61%) and Fuzhuan teas (3.33±0.23%). The tea polyphenols levels in the dark teas were approximately 10%, and no statistically significant differences (p>0.05) were found among the different types. Hexadecanoic acid was the most abundant aroma component in the dark teas, accounting for 15-20% of the total volatile oils. Moreover, the antioxidant activities of these dark teas were analyzed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) assay, ferric reducing antioxidant power (FRAP) assay, and cellular antioxidant activity (CAA) assay (HepG2 cells). The fat metabolism modulation activities (FMMA) of the dark teas were tested using a high-throughput screening method (SMMC-7221 cells). The results indicated that the different dark teas had diverse antioxidant activities, and the variation in the activities was significant. Correlation analysis showed that there was a significant positive correlation between the levels of EGCG and antioxidant activities measured using the ABTS (r=0.916) and FRAP (r=0.853) assays, and the levels of total flavonoids and theabrownins correlated well with the values determined using the CAA (r=0.845 and 0.865, respectively) assay.
黑茶富含多种次生代谢产物，如酚类和类黄酮，这些物质被认为与黑茶的健康益处有关。本研究系统检测了 44 个黑茶样品（包括普洱、茯砖和六堡茶）中的茶多酚、茶色素、儿茶素、类黄酮、生物碱和挥发性成分的浓度。在所测试的样品中，普洱茶总黄酮含量最高（5.24±0.05%），其次是六堡茶（4.45±0.61%）和茯砖茶（3.33±0.23%）。黑茶中的茶多酚含量约为 10%，不同类型之间没有统计学差异（p>0.05）。十六烷酸是黑茶中最丰富的香气成分，占总挥发油的 15-20%。此外，还使用 1,1-二苯基-2-苦基肼（DPPH）法、2,2'-联氮-双（3-乙基苯并噻唑啉-6-磺酸）二铵盐（ABTS）法、铁还原抗氧化能力（FRAP）法和细胞抗氧化活性（CAA）法（HepG2 细胞）分析了这些黑茶的抗氧化活性。使用高通量筛选方法（SMMC-7221 细胞）测试了黑茶的脂肪代谢调节活性（FMMA）。结果表明，不同的黑茶具有不同的抗氧化活性，且活性的变化显著。相关性分析表明，EGCG 水平与 ABTS（r=0.916）和 FRAP（r=0.853）测定的抗氧化活性之间存在显著正相关，总黄酮和茶褐素水平与 CAA 测定的结果（r=0.845 和 0.865）具有良好的相关性。
