An innovative approach to prepare hypericin molecularly imprinted pearls using a “phyto-template”

• Published in: Talanta (Oxford) Vol. 148; pp. 37 - 45
• Main Authors: Florea, Ana-Mihaela, Iordache, Tanța-Verona, Branger, Catherine, Ghiurea, Marius, Avramescu, Sorin, Hubca, Gheorghe, Sârbu, Andrei
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-02-2016; Elsevier
• Subjects: Chemical Sciences; Chromatography, High Pressure Liquid - methods; Hypericin; Hypericum; Hypericum Perforatum extract; Molecular Imprinting - methods; Molecularly imprinted polymers; Perylene - analogs & derivatives; Perylene - analysis; Perylene - metabolism; Phyto-template; Plant Extracts - analysis; Plant Extracts - metabolism; Polymers; Separation; Solid Phase Extraction - methods; Spectroscopy, Fourier Transform Infrared - methods; Wet phase inversion; Wet phase inversion; Molecularly imprinted polymers; Hypericin; Separation; Hypericum Perforatum extract; Phyto-template; Perforatum extract; Hypericum
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2015.10.061

In this paper, an innovative method that uses hypericin “phyto-template” molecules is being applied herein for the first time to produce molecularly imprinted polymer (MIP) pearls able to selectively retain hypericin from Hypericum Perforatum L primary extracts. For this purpose, the wet phase inversion method was preferred for preparing the hypericin-MIP pearls for several reasons referring to economical benefits but also due to the fact that hypericin “phyto-template” molecules can be generated along with the phase inversion of the copolymer. Practically, the precursor poly(acrylonitrile–co–methacrylic acid) solution was mixed with a purified and concentrated naphtodianthrone phyto-extract (consisting only of hypericin and pseudo-hypericin). In the subsequent phase inversion step hypericin was trapped in the copolymer droplets, as a result to its poor solubility in the inversion water bath, and further served as “phyto-template” in the imprinting step. This in situ repartition of hypericin and pseudo-hypericin was sustained by HPLC-DAD chromatograms which recorded only the presence of hypericin during the extraction stage of imprinted pearls. Batch rebinding measurements, all together, validated the efficiency of this innovative imprinting procedure. The hypericin rebinding of imprinted pearls was quantitative (up to 318µg/L) and approximately 5 times more specific relative to the blank pearls. Competitive re-binding revealed a more selective behaviour of imprinted pearls for hypericin when the up-take was measured against pseudohypericin (selectivity coefficient above 4.50).
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•An innovative hypericin “phyto-template” method is being applied for the first time.•MIPs were able to selectively retain hypericin from Hypericum Perforatum L extracts.•Adsorption rebinding measurements of pearls validated the imprinting efficiency.•The cavities specificity was highlighted against pseudohypericin and chlorophyll β.