Green extraction, chemical composition, and
in vitro antioxidant activity of theabrownins from Kangzhuan dark tea.
Curr Res Food Sci 2022;
5:1944-1954. [PMID:
36300163 PMCID:
PMC9589173 DOI:
10.1016/j.crfs.2022.10.019]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/29/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022] Open
Abstract
Theabrownins (TBs) in dark tea have received increasing attention for their multiple health benefits. In this study, ultrasound assisted extraction with deep eutectic solvent (UAE-DES) was developed for the extraction of TBs from Kangzhuan dark tea (KZDT). The highest yield (12.59%) of TBs was obtained using UAE-choline (ChCl)/malic acid (MA) with a liquid to solid ratio of 20:1 (v/w), ultrasonic power of 577 W, ultrasonic time of 25 min, and water content of 30%. TBs were further eluded by silica gel to obtain six theabrownine fractions (TBFs), namely, TBFs1, TBFs2, TBFs3, TBFs4, TBFs5, and TBFs6. LC-MS/MS revealed that flavonoids, terpenes, phenolic acids, alkaloids, lipids, and amino acids are the leading components of TBFs. The TBFs4, with the DPPH, ABTS, and FRAP values of 45.08 ± 0.42 μM Ascorbic acid/g DW, 178.52 ± 0.29 μM Trolox/g DW, and 370.85 ± 6.00 μM Fe(II)/g DW, respectively, showed the highest antioxidant activity among all the TBFs. Overall, this study first provided the evidence that UAE-ChCl/MA combining with silica gel was effective to extract TBs from KZDT, and the 6,7-dihydroxycoumarin-6-glucoside and neohesperidin were found as the leading compounds in the TBFs, providing a guidance for the chemical research and further utilization of dark tea and its TBs.
Yield of TBs of 12.59% from KZDT was achieved by UAE-ChCl/MA.
Silica gel powder with methanol (100%–0%) as a mobile phase was used for TBs separation.
The chemical component of TBFs was revealed.
Flavonoids are among the leading compounds in the TBFs.
TBFs4 displayed the highest in vitro antioxidant activity.
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