“Two-dimensional” molecularly imprinted solid-phase extraction coupled with crystallization and high performance liquid chromatography for fast semi-preparative purification of tannins from pomegranate husk extract

- Semi-preparative 2D-MIP-SPE was constructed to purify pomegranate husk extract.
- Ellagic acid and punicalagin imprinted polymers were prepared in batch mode.
- “Functional complementation” was used to evaluate the efficiency of 2D-MIP-SPE.
- Fractions obtained in 2D-MIP-SPE were further purified by crystallization and HPLC.

In this study, “two dimensional” molecularly imprinted solid-phase extraction (2D-MIP-SPE) of semi-preparative grade was constructed to fast purify ellagitannins in pomegranate husk extract with the help of crystallization and reverse-phase liquid chromatgoraphy (RPLC). Ellagic acid and punicalagin imprinted polymers were synthesized in batch mode and two semi-preparative MIP-SPE columns were individually packed. After investigaing “functional complementation”, 2D-MIP-SPE was constructed using ellagic acid MIP and punicalagin MIP-SPE as the first and second dimension, respectively. Then, pomegranate husk extract was fast divided into four fractions individually enriching in ellagic acid, granatin A, punicalagin and ellagic acid glucoside by 2D-MIP-SPE. With the aid of crystallization and RPLC, ellagic acid (13.5 mg) and punicalagin (53.4 mg) were fast obtained in 30 min. Ellagic acid glucoside was purified to the purity near 100% with a recovery of 86.1%. Granatin A (92%) was directly obtained by 2D-MIP-SPE with the recovery of 81.8%. All above indicated that 2D-MIP-SPE was highly efficient in natural product purification. The concept of “functional complementation” was expected to be a useful tool in the construction of 2D-MIP-SPE.