Content of selenoaminoacids and catechins in Chinese green teas

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ORIGINAL PAPER

Content of selenoaminoacids and catechins in Chinese green teas Aleksandra Sentkowska1 Received: 14 August 2020 / Revised: 4 November 2020 / Accepted: 7 November 2020 © The Author(s) 2020

Abstract In this study, famous Zhejiang teas were evaluated as a well-advertised source of selenium. The 25 samples from provinces around China and Asia were purchased in Warsaw tea shops. The speciation analysis of selenium as well as the evaluation of catechin content in water tea infusions was performed using hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS/MS). It turned out that all of tested samples can be a great source of organic selenium species (no traces of inorganic selenium was found), however, Zhejiang teas did not differ much among others. Such a conclusion can also be drawn when comparing the antioxidant capacity of the tested samples, obtained with the application of four methods (Folin–Ciocalteu method, scavenging of the 2,2-diphenyl-1-picrylhydrazyl radical, hydroxyl radical scavenging and cupric reducing ability assay). What is more, no correlation was found between the selenium content and the antioxidant activity of studied teas. The results obtained for the six samples from Zhejiang Province were very varied, which shows that it is very difficult to interpret the results and compare them with the results of other authors. Keyword  Green tea · Selenoaminoacids · Catechins · Antioxidant properties

Introduction Tea is the second most widely consumed beverage after water and its popularity is not only due to a great taste but also to its health-promoting properties, especially for green tea [1, 2]. Several studies have confirmed the positive role of green tea in preventing cardiovascular and degenerative diseases, likely due to the antioxidant properties of polyphenolic compounds [3, 4]. The major polyphenols in green tea are flavonoids, the most active of which are catechins and epigallocatechin gallate [5]. These compounds exert their antioxidant and antiradical properties by several mechanisms including direct scavenging of reactive oxygen species, chemical reducing activity, complexation of pro-oxidant metal ions, activation of antioxidant enzymes and inhibition of oxidases [6]. The newest studies proved that green tea catechins inhibit microglial activation which prevents Electronic supplementary material  The online version of this article (https​://doi.org/10.1007/s0021​7-020-03650​-5) contains supplementary material, which is available to authorized users. * Aleksandra Sentkowska [email protected] 1



Heavy Ion Laboratory, University of Warsaw, Pasteura 5A, 02‑093 Warsaw, Poland

the development of neurological disorders as well as play a significant role in cancer prevention and therapy [7, 8]. Over the past years, a growing interest in Chinese green tea particularly produced in Ziyang County located in the southwest of Shaanxi Province has been observed. Almost all Chinese tea contain selenium but with different content but Ziyang tea, in