Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Oct 20;23(20):12600.
doi: 10.3390/ijms232012600.

Exploring the Absorption Mechanisms of Imidazolium-Based Ionic Liquids to Epigallocatechin Gallate

Yingjie Luo  1 , Yiwei Zhang  1 , Cimin Tao  1 , Hongfei Ni  1 , Xuesong Liu  1 , Yong Chen  1 , Yongjiang Wu  1 , Hang Song  2 , Tengfei Xu  1
Affiliations

Exploring the Absorption Mechanisms of Imidazolium-Based Ionic Liquids to Epigallocatechin Gallate

Yingjie Luo et al. Int J Mol Sci. .

Abstract

Imidazolium-based ionic liquids are wildly used in natural product adsorption and purification. In this work, one typical polymeric ionic liquid (PIL) was synthesized by using L-proline as the anion, which exhibited excellent adsorption capacity toward tea polyphenol epigallocatechin gallate (EGCG). The adsorption conditions were optimized with the response surface method (RSM). Under the optimum conditions, the adsorption capacity of the PIL for EGCG can reach as high as 552 mg/g. Dynamics and isothermal research shows that the adsorption process of EGCG by the PIL particularly meets the quasi-second-order kinetic equation and monolayer adsorption mechanism. According to thermodynamic parameter analysis, the adsorption process is endothermic and spontaneous. The results of theoretical calculation by molecular docking also demonstrated the interaction mechanisms between EGCG and the ionic liquid. Considering the wide application of imidazolium-based ionic liquids in component adsorption and purification, the present study can not only be extended to other similar experimental mechanism validation, but also be representative for guiding the synthesis of PIL and optimization of adsorption conditions.

Keywords: epigallocatechin gallate; ionic liquids; mechanism; molecular docking; polymer.

PubMed Disclaimer

Conflict of interest statement

The authors declare that they have no known competing financial interest or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Figure 1
Figure 1
The IR spectrum of IL, MBA and Polymer.
Figure 2
Figure 2
Confirmation of EGCG absorbed by PILs specifically. (a): Chromatograms of the TPs before (red line) and after (blue line) incubated with PILs, the theophylline was spiked as the internal reference. (b): Chromatograms of the green tea extracts before (red line) and after (blue line) incubated with PILs.
Figure 3
Figure 3
Single-factor optimization of the absorption process of (ViIm)2C6(L-Pro)2 to EGCG. (a): pH of the adsorption solution; (b): adsorption temperature; (c): adsorption time and (d): the solid–liquid ratio in the adsorption process.
Figure 4
Figure 4
The adsorption kinetics curve of the adsorption process of EGCG by PILs. (a): Three typical temperatures (25 °C, 35 °C and 45 °C) were investigated to explore the adsorption kinetics. The fitted plots of the pseudo-first-order (b) and pseudo-second-order (c) kinetic models are based on the adsorption capacity–temperature results.
Figure 5
Figure 5
The comparison of the different temperatures (25 °C, 35 °C and 45 °C) on the adsorption capacity (Qe, mg/g) at different initial concentrations (Ce, mg/L).
Figure 6
Figure 6
The fitted plots of Freundlich (a) and Langmuir (b) equations.
Figure 7
Figure 7
The linear plot of ln(Kc) to 1/T response to PILs absorbing of EGCG.
Figure 8
Figure 8
(a) The optimized molecular geometric structure of (ViIm)2C6(L-Pro)2 (IL), theophylline and EGCG. (b) The ESP of (ViIm)2C6(L-Pro)2 (IL), theophylline and EGCG.
Figure 9
Figure 9
(a) Structure model diagram of (ViIm)2C6(L-Pro)2-theophylline/EGCG complex. (b) Surface penetration diagrams of the electrostatic potential of (ViIm)2C6(L-Pro)2-theophylline/EGCG complex.
Figure 10
Figure 10
Solubility of various substances in ILs at different temperatures.
Figure 11
Figure 11
The desorption efficiency of EGCG under various desorption solvents (a) and time (b). The A, B, C, D, E and F indicates ethyl acetate, methanol, ethanol, 5% aqueous hydrochloric acid, 2% methanol hydrochloric acid and 5% methanol hydrochloric acid, respectively.
Figure 12
Figure 12
(a) The reusability of PILs and (b) the recycle time of PILs.
Figure 13
Figure 13
SEM characterization of PILs before adsorption, after adsorption and after desorption.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

References

    1. Jin X., Liu M., Chen Z., Mao R., Xiao Q., Gao H., Wei M. Separation and purification of epigallocatechin-3-gallate (EGCG) from green tea using combined macroporous resin and polyamide column chromatography. J. Chromatogr. B. 2015;1002:113–122. doi: 10.1016/j.jchromb.2015.07.055. - DOI - PubMed
    1. Mandal P., Misra T.K., Singh I.D. Antioxidant activity in the extracts of two edible aroids. Indian J. Pharm. Sci. 2010;72:105–108. - PMC - PubMed
    1. Singh B.N., Shankar S., Srivastava R.K. Green tea catechin, epigallocatechin-3-gallate (EGCG): Mechanisms, perspectives and clinical applications. Biochem. Pharmacol. 2011;82:1807–1821. doi: 10.1016/j.bcp.2011.07.093. - DOI - PMC - PubMed
    1. Wang L., Gong L.H., Chen C.J., Han H.B., Li H.H. Column-chromatographic extraction and separation of polyphenols, caffeine and theanine from green tea. Food Chem. 2012;131:1539–1545. doi: 10.1016/j.foodchem.2011.09.129. - DOI
    1. Dong W.B., Hu Y., Zhang J.H. Study on the Process of Preparation of TPs by Adsorption Resin Method. Food Sci. 2002;23:68–73.

Grants and funding

LinkOut - more resources