Quality Assessment and Quantitative Analysis of Flavonoids from Tea Samples of Different Origins by HPLC-DAD-ESI-MS

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• 作者：Tahira Sultana ; Guenther Stecher ; Robert Mayer ; Lukas Trojer ; Muhammad Nasimullah Qureshi ; Gudrun Abel ; Michael Popp ; Guenther Karl Bonn
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2008
• 出版时间：May 28, 2008
• 年：2008
• 卷：56
• 期：10
• 页码：3444 - 3453
• 全文大小：713K
• 年卷期：v.56,no.10(May 28, 2008)
• ISSN：1520-5118

文摘

Components of green tea (Camellia sinensis) have been of considerable interest in recent years because of their potential utility as pharmaceutical agents, particularly for their antioxidant and anticarcinogenic activity. Responding to the increasing scientific validation of numerous health benefits of tea, a comprehensive approach was adopted to carry out analysis for the quality assessment of flavonoids in tea samples of different origins. For this purpose, extraction, separation, and mass spectrometric parameters were optimized. Extraction methods evaluated include reflux extraction, a modified accelerated solvent extraction (ASE), namely, Aquasolv extraction, and microwave-assisted extraction (MAE) using different percentages of solvents. Separation was performed by a specifically developed reversed phase high-performance liquid chromatography (RP-HPLC) method using different C18 and C8 stationary phases. Optimization of extraction techniques clearly proved the performance of MAE, which delivered highest yields in a very short time. Additionally, the comparison with Aquasolv extraction provided new insights, as variations in quantified amounts of target compounds between the extracts could be explained on the basis of thermal degradation and epimerization phenomena. Especially the epimerization phenomenon for catechin/epicatechin oligomers, that is, of procyanidins P₂ and P₃, was observed for the first time. Finally, an optimized extraction and separation system was used for qualitative and quantitative investigations of compounds from different green tea samples from Ceylon (cultivated under biologically controlled conditions), Japan, India, and China as well as from one black tea sample from India.