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doi:10.1016/j.chroma.2006.10.026 
Copyright © 2006 Elsevier B.V. All rights reserved.
Uniformly-sized, molecularly imprinted polymers for (−)-epigallocatechin gallate, -epicatechin gallate and -gallocatechin gallate by multi-step swelling and polymerization method
Jun Haginakaa, 
, 
, Hiromi Taboa, Masaki Ichitanib, Takanobu Takiharab, Akio Sugimotob and Haruyo Sambea
Available online 27 October 2006.
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Abstract
Uniformly-sized, molecularly imprinted polymers (MIPs) for (−)-epigallocatechin gallate (EGCg), -epicatechin gallate (ECg) and -gallocatechin gallate (GCg) were prepared by a multi-step swelling and polymerization method using 2-vinylpyridine as a functional monomer, ethylene glycol dimethacrylate as a cross-linker and cyclohexanol as a porogen. Molecular recognition abilities of the obtained MIPs were evaluated in liquid chromatography using a mixture of ethanol and water, or ethanol as the eluent. Each MIP gave the highest molecular recognition ability for the respective template molecule. In addition, (−)-EGCg and -ECg had the same configuration (2R,3R) at positions 2 and 3, and therefore resulting in high cross reactivity each other. However, (−)-GCg, which has different configuration at position 2 with (−)-EGCg and -ECg, showed low cross reactivity with them. On the other hand, those MIPs showed no molecular recognition against (−)-epigallocatechin and -epicatechin, which have no gallate group at position 3. These results indicate that the MIPs prepared can recognize configuration at position 2 and a gallate group at position 3. Furthermore, the MIP for (−)-GCg could be successfully used for isolating (−)-EGCg and -ECg from green tea extract.
Keywords: Molecular recognition; Molecularly imprinted polymer; LC stationary phase; Epigallocatechin gallate; Epicatechin gallate; Gallocatechin gallate
Article Outline
- 1. Introduction
- 2. Experimental
- 2.1. Reagents and materials
- 2.2. Isolation of (−)-GCg
- 2.3. Preparation of MIPs by a multi-step swelling and polymerization method
- 2.4. Chromatographic evaluation of MIPs
- 2.5. Application of MIP for isolation of (−)-EGCg and -ECg in green tea extract
- 3. Results and discussion
- 3.1. Preparation of MIP by a multi-step swelling and polymerization method
- 3.2. Retention properties of MIPs for (−)-EGCg
- 3.3. Molecular recognition properties of MIPs for (−)-EGCg, -ECg and -GCg
- 3.4. Application of MIPGCg for isolation of (−)-EGCg and -ECg in green tea extract
- 4. Conclusions
- Acknowledgements
- References
) (−)-ECg; (×) (−)-GCg; (○) (−)-EGC; (
) (−)-EC. HPLC conditions: column size, 4.6 mm i.d. × 50 mm; column temperature, 25 °C; flow rate, 0.5 mL/min; eluent, ethanol–sodium phosphate (7:3, v/v); detection, 210 nm; loaded amount, 1500 ng.
