Abstract
The development of molecularly imprinted polymers (MIPs) to target polyphenols present in vegetable extracts was here addressed. Polydatin was selected as a template polyphenol due to its relatively high size and amphiphilic character. Different MIPs were synthesized to explore preferential interactions between the functional monomers and the template molecule. The effect of solvent polarity on the molecular imprinting efficiency, namely owing to hydrophobic interactions, was also assessed. Precipitation and suspension polymerization were examined as a possible way to change MIPs morphology and performance. Solid phase extraction and batch/continuous sorption processes were used to evaluate the polyphenols uptake/release in individual/competitive assays. Among the prepared MIPs, a suspension polymerization synthesized material, with 4-vinylpyridine as the functional monomer and water/methanol as solvent, showed a superior performance. The underlying cause of such a significant outcome is the likely surface imprinting process caused by the amphiphilic properties of polydatin. The uptake and subsequent selective release of polyphenols present in natural extracts was successfully demonstrated, considering a red wine solution as a case study. However, hydrophilic/hydrophobic interactions are inevitable (especially with complex natural extracts) and the tuning of the polarity of the solvents is an important issue for the isolation of the different polyphenols.
Highlights
Polyphenols are organic compounds produced by plants to provide them protection to different kinds of attacks such as UV radiation, parasites, insect pests and many other environmental threats.Close to 10,000 different polyphenols have already been identified
Polydatin is a natural precursor of resveratrol, which is present in many vegetable extracts, with possible important beneficial effects on human health, namely the protection against hemorrhagic shock, ischemia/reperfusion, heart failure, endometriosis and cancer
Different kinds of molecularly imprinted polymers (MIPs) were synthesized by changing the functional monomers (acrylic acid, methacrylic acid, 4-vinylpyridine, acrylamide, 2-(dimethylamino)ethyl methacrylate and
Summary
Polyphenols are organic compounds produced by plants to provide them protection to different kinds of attacks such as UV radiation, parasites, insect pests and many other environmental threats. Close to 10,000 different polyphenols have already been identified. Their incidence changes among the different plant species, as well as the kind of vegetable parts (roots, stalks, barks, leaves, fruits, skin-fruits, shells, seeds, stones, etc.) inside the same species [1]. Besides the preventive effects on human health, polyphenols are being considered in the treatment of several diseases [1]. Owing to these useful properties, a growing interest on these natural compounds is being observed namely by the pharmaceutical, biomedical, biotechnological and cosmetics industries [1]. The development of techniques and processes to perform the efficient extraction, purification, fractionation, isolation and concentration of polyphenols is a subject attracting wide interest from the scientific community and the Processes 2017, 5, 72; doi:10.3390/pr5040072 www.mdpi.com/journal/processes
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