Morlock Gertrud E, Heil Julia, Inarejos-Garcia Antonio M, Maeder Jens
Institute of Nutritional Science, and TransMIT Center for Effect-Directed Analysis, Justus Liebig University Giessen, Heinrich Buff Ring 26-32, 35392 Giessen, Germany.
Department of Functional Extracts, ADM Wild Valencia, 46740 Carcaixent, Spain.
Antioxidants (Basel). 2021 Jan 15;10(1):117. doi: 10.3390/antiox10010117.
The antioxidative activity of tea and especially powdered tea extracts on the market, among others used as added value in functional foods, can considerably vary due to not only natural variance, but also adulteration and falsification. Thus, an effect-directed profiling was developed to prove the functional effects or health-promoting claims. It took 3-12 min per sample, depending on the assay incubation time, for 21 separations in parallel. Used as a fast product quality control, it can detect known and unknown bioactive compounds. Twenty tea extracts and a reference mixture of 11-bioactive compounds were investigated in parallel under the same chromatographic conditions by a newly developed reversed phase high-performance thin-layer chromatographic method. In eight planar on-surface assays, effect-directed tea profiles were revealed. Catechins and theaflavins turned out to be not only highly active, but also multi-potent compounds, able to act in a broad range of metabolic pathways. The flavan-3-ols acted as radical scavengers (DPPH assay), antibacterials against Gram-positive bacteria, and inhibitors of tyrosinase, α-glucosidase, β-glucosidase, and acetylcholinesterase. Further effects against Gram-negative bacteria and β-glucuronidase were assigned to other components in the powdered tea extracts. According to their specifications, the activity responses of the powdered tea extracts were higher than in mere leaf extracts of green, white and black tea. The multi-imaging and effect-directed profiling was not only able to identify known functional food ingredients, but also to detect unknown bioactive compounds (including bioactive contaminants, residues or adulterations).
茶叶尤其是市售速溶茶提取物的抗氧化活性，除了用于功能性食品中作为附加值外，由于不仅存在自然差异，还存在掺假和伪造情况，其活性可能会有很大差异。因此，开发了一种效应导向分析方法来证明其功能效果或健康促进功效。根据分析孵育时间，每个样品需要3 - 12分钟，可同时进行21次分离。作为一种快速的产品质量控制方法，它可以检测已知和未知的生物活性化合物。通过新开发的反相高效薄层色谱法，在相同的色谱条件下对20种茶叶提取物和11种生物活性化合物的参考混合物进行了平行研究。在八项平面表面分析中，揭示了效应导向的茶叶图谱。儿茶素和茶黄素不仅具有高活性，而且是多效化合物，能够作用于广泛的代谢途径。黄烷 - 3 - 醇作为自由基清除剂（DPPH分析）、抗革兰氏阳性菌的抗菌剂以及酪氨酸酶、α - 葡萄糖苷酶、β - 葡萄糖苷酶和乙酰胆碱酯酶的抑制剂。对革兰氏阴性菌和β - 葡萄糖醛酸酶的其他作用归因于速溶茶提取物中的其他成分。根据其规格，速溶茶提取物的活性反应高于单纯的绿茶、白茶和红茶叶提取物。多成像和效应导向分析不仅能够识别已知的功能性食品成分，还能够检测未知的生物活性化合物（包括生物活性污染物、残留物或掺假物）。
