Content of selenoaminoacids and catechins in Chinese green teas

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.

Analytical Problems in Separation of Selenomethionine and Its Oxidative Product in HILIC HPLC

“…The chromatogram of water extract of Chinese green tea Lung-Ching (sample 3), under the conditions described earlier [ 29 , 40 ], is presented in Figure 1 B. The analytes were identified by comparing retention times and m/z values obtained by MS and MS 2 mass spectra ( Figure 1 A).…”

“…Compared to the previously proposed method for selenium speciation analysis [ 29 , 40 ], where SeMetO was not evaluated, the aqueous component of the mobile phase (ammonium acetate pH 7) was replaced with water. This resulted in the change in the elution order—MeSeCys was eluted before SeMet.…”

“…The pKa values of selenium species are in the range from 2.8 to 4.8, so at pH 5.8 (value refers to pH of water component of the eluent), they are all negatively charged. It should be highlighted that in the separation of selenium species, methanol seems to be the better choice as the mobile phase component [ 29 , 40 ]. Methanol is a stronger eluent than acetonitrile and is known to be adsorbed near the stationary phase via hydrogen bonding with the residual silanols, while acetonitrile can react with silanols via dipol–dipol interaction [ 47 ].…”

Weak Binding of Epigallocatechin to α-Lactalbumin Greatly Improves Its Stability and Uptake by Caco-2 Cells

“…As the second most widely consumed beverage after water, tea is endowed with high popularity, which is not only due to its great taste but also to its health-promoting properties. 1,2 Catechins (flavan-3-ols), considered as inexpensive, readily applicable, and safe phytochemicals, are the principal bioactive compounds in tea polyphenols. 3 Based on decades of research, burgeoning evidence has confirmed that catechins possess antioxidant, anti-inflammatory, anti-proliferative, anti-angiogenic, and antimetastatic effects by modulating signaling pathways, enzymatic activity, and protein kinases.…”

“…Natural products from plants traditionally have provided the food industry with one of their most important functions as nutritional supplementation. As the second most widely consumed beverage after water, tea is endowed with high popularity, which is not only due to its great taste but also to its health-promoting properties. , Catechins (flavan-3-ols), considered as inexpensive, readily applicable, and safe phytochemicals, are the principal bioactive compounds in tea polyphenols . Based on decades of research, burgeoning evidence has confirmed that catechins possess antioxidant, anti-inflammatory, anti-proliferative, anti-angiogenic, and anti-metastatic effects by modulating signaling pathways, enzymatic activity, and protein kinases. , The natural structures of catechins are characterized by di- or tri-hydroxyl group substitution of the B ring and the meta-5,7-dihydroxy substitution of the A ring .…”