Molecularly imprinted polymers for the isolation of bioactive naphthoquinones from plant extracts.
Molecularly Imprinted Polymers (MIPs) targeting shikonin, a potent antioxidant and wound healing agent, have been prepared using methacrylic acid (MAA) and 2-diethylaminoethyl methacrylate (DEAEMA) as functional monomers. An investigation of solution association between shikonin and both acidic and basic functional monomers by UV-vis titrations, suggested stronger affinity towards the basic functionality. Strong inhibition of the co-polymerisation reaction of such basic monomers was observed, but was overcome by reduction of the amount of template used during polymer synthesis. Polymer morphology was severely impacted by the template's radical scavenging behaviour as demonstrated by solid state NMR spectroscopy measurements. HPLC evaluation of the final materials in polar conditions revealed limited imprinting effects and selectivity, with the MAA polymers exhibiting marginally better performance. During application of the polymers as MI-SPE sorbents in non-polar solvents it was found that the DEAEMA based polymer was more selective towards shikonin compared to the MAA counterpart, while shikonin recoveries of up to 72% were achieved from hexane solutions of a commercial sample of shikonin, hexane extract of Alkanna tinctoria roots and a commercial pharmaceutical ointment.
Organic Chemistry Laboratory, Chemical Engineering Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Stella K
SK
Tsermentseli
Panagiotis
P
Manesiotis
Andreana N
AN
Assimopoulou
Vassilios P
VP
Papageorgiou
D028082:Boraginaceae / Q000737:chemistry; D004365:Drugs, Chinese Herbal; D008689:Methacrylates / Q000737:chemistry; D054802:Molecular Imprinting / Q000379:methods*; D009285:Naphthoquinones / Q000032:analysis / Q000302:isolation & purification*; D010936:Plant Extracts / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry; D052616:Solid Phase Extraction / Q000379:methods*
D004365:Drugs, Chinese Herbal; D008689:Methacrylates; D009285:Naphthoquinones; D010936:Plant Extracts; C016101:shikonin
Alkannin; Molecularly Imprinted Solid Phase Extraction (MI-SPE); Naphthazarin; Plant extracts; Shikonin; Wound healing agents