Correlation of polyphenol content and antioxidant capacity of selected teas and tisanes from Brazilian market

Abstract In this work, it was evaluated the phenolic content, redox behavior and antioxidant capacity of several selected teas and tisanes from Brazilian market. The samples were classified as simple (single herb) or composed (blend of two or more herbs). In addition, complementary multivariate statistical approaches were used to identify the correlation and interdependence between the amount of major phytocomponents, such as phenols and flavonoids, as well as the antioxidant activity of the products. Results showed that the total polyphenol and total flavonoid concentrations are correlated to thermodynamic feasibility of reactive oxygen species reduction. The statistical modeling differentiated the results datasets in principal components, whose flavonoid content presented itself as the main parameter to segregate data between simple and composed products. On the other hand, the whole polyphenol content, in both teas and tisanes, was more relevant regarding their antioxidant capacity than the flavonoids content. Considering that the manufactures do not display the real amount of each herb in the labels of the composed products, it was not possible to confirm whether the blends of several species lead to a substantial enhancement on their antioxidant capacity. Furthermore, the redox profile and overall polyphenol content suggest that the consumption of green and black teas as well as traditional yerba mate may be worthwhile in preventing ailments associated with oxidative stress in Brazilian population. Notwithstanding, further clinical studies are required to validate this hypothesis.摘要：本研究对巴西市场上甄选的多款茶类及草本茶饮（tisane）的酚类物质含量、氧化还原行为与抗氧化能力开展了评估。实验样本被划分为单一草本型（仅含单一种类草本）与复合草本型（由两种及以上草本复配而成）两类。此外，本研究采用补充性多元统计方法，探究主要植物成分（phytocomponents，如酚类与黄酮类（flavonoids））的含量与产品抗氧化活性之间的相关性及相互依存关系。结果显示，总多酚与总黄酮浓度与活性氧（reactive oxygen species）还原的热力学可行性呈显著相关。通过统计建模的主成分（Principal Components）分析对数据集进行分组区分，其中黄酮类物质含量是区分单一与复合产品的核心参数。另一方面，相较于黄酮类含量，茶与草本茶饮的总多酚含量对抗氧化能力的贡献更为显著。鉴于生产商未在复合产品的标签上标注每种草本的实际添加量，无法确认多种草本复配是否会显著提升其抗氧化能力。此外，氧化还原特征与总多酚含量提示，饮用绿茶、红茶以及传统马黛茶（yerba mate）或有助于巴西人群预防与氧化应激相关的疾病。尽管如此，仍需开展进一步临床研究以验证这一假说。