Determination of methylxanthine contents and risk characterisation for various types of tea in Korea

Baek, Ga-Hyun; Yang, Sung-Woong; Yun, Choong-In; Lee, Joon‐Goo; Kim, Young‐Jun

doi:10.1016/j.foodcont.2021.108543

Cited by 8 publications

(8 citation statements)

References 25 publications

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“…The data are shown in Table 1 and Figure S5 . The TP content of jasmine tea, black tea, and green tea are 5.80, 4.31, and 1.53 μg/g, respectively, but oolong tea and rabbit plasma are not detected, which is consistent with the previous reports [ 2 , 3 ]. Furthermore, high levels of theobromine and caffeine that are hundreds and thousands of times higher than TP are found in the four tea samples.…”

Section: Resultssupporting

confidence: 92%

“…Theophylline (1,3-dimethyl-7 H -purine-2,6-dione) (TP) is a dimethylxanthine derived from the xanthine purine base of alkaloid, which occurs naturally in most kinds of teas (jasmine tea, black tea, oolong tea, etc.) and cocoa beans in trace amounts [ 1 , 2 , 3 ]. TP is an important bioactive component of tea, which has various bioactivities at low doses [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

“…This method is a simple operation and has good magnetic properties, but a relatively small specific surface area leads to a low extraction efficiency. (2) In situ growth of magnetic NPs [36], which is based on the prepared MOF, followed by dispersion in the precursor solution of the Fe 3 O 4 NPs, but the original morphology of MOF will be destroyed. (3) Single-step MOF coating [37], the prepared magnetic NPs with proper modifications are added to a solution containing the precursors of MOF, which can maintain the maximum degree of morphology of MOF, having a large specific surface to obtain a high adsorption capacity.…”

Section: Introductionmentioning

confidence: 99%

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Ultra-High Adsorption Capacity of Core–Shell-Derived Magnetic Zeolite Imidazolate Framework-67 as Adsorbent for Selective Extraction of Theophylline

et al. 2023

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A core–shell-derived structural magnetic zeolite imidazolate framework-67 (Fe3O4-COOH@ZIF-67) nanocomposite was fabricated through a single-step coating of zeolite imidazolate framework-67 on glutaric anhydride-functionalized Fe3O4 nanosphere for the magnetic solid-phase extraction (MSPE) of theophylline (TP). The Fe3O4-COOH@ZIF-67 nanocomposite was characterized through scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, Zeta potential analysis, X-ray diffraction, Brunauer–Emmett–Teller, and vibrating sample magnetometer. The material has a high specific surface area and good magnetism, which maintains the regular dodecahedron structure of ZIF-67 without being destroyed by the addition of Fe3O4-COOH nanospheres. The Fe3O4-COOH@ZIF-67 can rapidly adsorb TP mainly through the strong coordination interaction between undercoordinated Co2+ on ZIF-67 and –NH from imidazole of TP. The adsorption and desorption conditions, such as the amount of adsorbent, adsorption time, pH value, and elution solvent, were optimized. The kinetics of TP adsorption on Fe3O4-COOH@ZIF-67 was found to follow pseudo-second-order kinetics. The Langmuir model fits the adsorption data well and the maximum adsorption capacity is 1764 mg/g. Finally, the developed MSPE-HPLC method was applied in the enrichment and analysis of TP in four tea samples and rabbit plasma. TP was not detected in oolong tea and rabbit plasma, and its contents in jasmine tea, black tea, and green tea are 5.80, 4.31, and 1.53 μg/g, respectively. The recoveries of spiked samples are between 74.41% and 86.07% with RSD in the range of 0.81–3.83%. The adsorption performance of Fe3O4-COOH@ZIF-67 nanocomposite was nearly unchanged after being stored at room temperature for at least 80 days and two consecutive adsorption–desorption cycles. The results demonstrate that Fe3O4-COOH@ZIF-67 nanocomposite is a promising magnetic adsorbent for the preconcentration of TP in complex samples.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultra-High Adsorption Capacity of Core–Shell-Derived Magnetic Zeolite Imidazolate Framework-67 as Adsorbent for Selective Extraction of Theophylline

et al. 2023

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“…Other teas also contain compounds of these chemical classes, with differences in the specific types and quantities of their substances. For example, chamomile tea does not contain caffeine, while black, green, pu-erh, and oolong teas contain varying high amounts of caffeine [63]. Catechin is found in a very high quantity in green tea due to its minimized antioxidant capacity compared to chamomile, black, and peppermint tea [64,65], and chamomile tea is also the richest in apigenin in contrast to peppermint tea [66].…”

Section: Discussionmentioning

confidence: 99%

COX2-Inhibitory and Cytotoxic Activities of Phytoconstituents of Matricaria chamomilla L.

et al. 2023

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Chamomile tea is a popular beverage and herbal remedy with various health benefits, including antioxidant and antimicrobial activities and beneficial effects on metabolism. In this study, we investigated the inhibitory activities of secondary metabolites from Matricaria chamomile L. against COX2, an enzyme involved in inflammation and linked to cancer development. The cytotoxicity of the compounds was also evaluated on a panel of 60 cancer cell lines. Myricetin, one of the COX2-inhibiting and cytotoxic compounds in chamomile tea, was further studied to determine a proteomic expression profile that predicts the sensitivity or resistance of tumor cell lines to this compound. The expression of classical mechanisms of anticancer drug resistance did not affect the responsiveness of cancer cells to myricetin, e.g., ATP-binding cassette (ABC) transporters (ABCB, ABCB5, ABCC1, ABCG2), tumor suppressors (p53, WT1), and oncogenes (EGFR, RAS), whereas significant correlations between myricetin responsiveness and GSTP expression and cellular proliferation rates were observed. Additionally, Kaplan–Meier survival time analyses revealed that high COX2 expression is associated with a worse survival prognosis in renal clear cell carcinoma patients, suggesting a potential utility for COX2 inhibition by myricetin in this tumor type. Overall, this study provides insight into the molecular modes of action of chamomile secondary metabolites and their potential as cancer-preventive or therapeutic agents.

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“…Since CAF and THEO are both present in tea, commercial teas were chosen as real matrices to test the resulting optimized sensor. Moreover, due to the low content of THEO in teas with respect to CAF, as generally reported [ 19 ], a commercial drug containing THEO was analyzed, too, to evaluate the suitability of the presented method for the determination of higher amounts of THEO in a complex matrix.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Sensing Platform Based on Carbon Dots for the Simultaneous Determination of Theophylline and Caffeine in Tea

Di Matteo,

Trani,

Bortolami

et al. 2023

Sensors

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A simple and selective method for the determination of caffeine (CAF) and theophylline (THEO) has been developed for a glassy carbon electrode (GCE) modified with a composite including carbon dots (CDs) and chitosan (CS). To our knowledge, there are no previous studies that analyze a CDs-modified GCE for the presence of CAF and THEO. The electrochemical behavior of a GCE modified with a CDs-CS composite was studied in acidic medium by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Considering the sensor analytical parameters, the same linear concentrations range was found for CAF and THEO ranging from 1 × 10−5 to 5 × 10−3 mol L−1 with the same detection limit (LOD) of 1 × 10−6 mol L−1. The reproducibility and repeatability data were satisfactory in terms of RSD%. Moreover, the storage stability was evaluated, evidencing good results whatever the experimental conditions used. The developed sensor was applied for the simultaneous determination of CAF and THEO in tea and drug, and results were compared with those obtained with HPLC-ESI-MS in SIR mode as an independent method optimized on purpose. The electrochemical sensor presents the undoubled advantages in terms of cheapness, portability, and ease of use, since it does not require skilled personnel.

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Determination of methylxanthine contents and risk characterisation for various types of tea in Korea

Cited by 8 publications

References 25 publications

Ultra-High Adsorption Capacity of Core–Shell-Derived Magnetic Zeolite Imidazolate Framework-67 as Adsorbent for Selective Extraction of Theophylline

Ultra-High Adsorption Capacity of Core–Shell-Derived Magnetic Zeolite Imidazolate Framework-67 as Adsorbent for Selective Extraction of Theophylline

COX2-Inhibitory and Cytotoxic Activities of Phytoconstituents of Matricaria chamomilla L.

Electrochemical Sensing Platform Based on Carbon Dots for the Simultaneous Determination of Theophylline and Caffeine in Tea

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