Abstract
Molecularly imprinted polymers (MIPs) prepared via a semi-covalent imprinting strategy using stigmasteryl methacrylate as a polymerisable template have been evaluated by static binding methods for their ability to selectively capture other valuable phytosterol targets, including campesterol and brassicasterol. Design criteria based on molecular modelling procedures and interaction energy calculations were employed to aid the selection of the co-monomer type, as well as the choice of co-monomer:template ratios for the formation of the pre-polymerisation complex. These novel hybrid semi-covalently imprinted polymers employed N,N′-dimethylacryl-amide (N,N′-DMAAM) as the functional co-monomer and displayed specific binding capacities in the range 5.2–5.9 mg sterol/g MIP resin. Their binding attributes and selectivities towards phytosterol compounds were significantly different to the corresponding MIPs prepared via non-covalent procedures or when compared to non-imprinted polymers. Cross-reactivity studies using stigmasterol, ergosterol, cholesterol, campesterol, and brassicasterol as single analytes revealed the importance of the A-ring C-3-β-hydroxyl group and the orientational preferences of the D-ring alkyl chain structures in their interaction in the templated cavity with the N,N′-dimethylamide functional groups of the MIP. Finally, to obtain useful quantities of both campersterol and brassicasterol for these investigations, improved synthetic routes have been developed to permit the conversion of the more abundant, lower cost stigmasterol via a reactive aldehyde intermediate to these other sterols.
Highlights
Phytosterols are naturally occurring bioactive compounds, which have attracted wide-spread interest in recent years within the biomedical research and pharmaceutical/nutraceutical communities due largely for their ability to (i) lower blood serum levels of LDL-cholesterol; (ii) inhibit oxidative stress and cellular deterioration; (iii) act as anti-inflammatory compounds; and (iv) for their role as steroidal intermediates and precursors in the production of several pharmaceuticals [1,2,3]
The observed binding was largely associated with non-specific interactions. These studies confirmed an earlier report on the failure of the monomers methacrylic acid (MAA) and 4-VP to generate by non-covalent self-assembly approaches stigmasterol-imprinted polymers with acceptable imprinting factors [28]. This outcome can be attributed to an inability to form a stable pre-polymerisation complex, involving the functional monomers and the sterol template, owing to the presence of only a single A-ring C-3β-hydroxyl group of the sterol capable of forming a hydrogen bond with, for example, the N,N 0 -dimethylamido group of the N,N 0 -DMAAM monomer
An alternative strategy was adopted based on the use of a semi-covalent Molecularly imprinted polymers (MIPs) approach with the functional monomer and template combined via a formal covalent linkage
Summary
Phytosterols are naturally occurring bioactive compounds, which have attracted wide-spread interest in recent years within the biomedical research and pharmaceutical/nutraceutical communities due largely for their ability to (i) lower blood serum levels of LDL-cholesterol; (ii) inhibit oxidative stress and cellular deterioration; (iii) act as anti-inflammatory compounds; and (iv) for their role as steroidal intermediates and precursors in the production of several pharmaceuticals [1,2,3]. An opportunity exists to explore alternative, more cost-effective technologies of lower energy consumption for the separation and purification of these valuable compounds from natural sources, including food and oil processing waste streams. In this context, molecularly imprinted polymers (MIPs) represent an attractive option for the isolation of phytosterols, since these functional polymers have been employed for other classes of compounds as re-usable adsorbents in solid-phase tank batch extraction procedures or packed-bed chromatographic formats [7,8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
