Synthesis of a molecularly imprinted polymer to isolate glucosamine from plant extracts by an ionic-non-covalent dual approach.

The objective of this study was to synthesize a novel glucosamine-imprinted sorbent based on ionic and non-covalent dual approach to purify glucosamine from chicory root extracts. The synthesis of the molecularly imprinted polymer was optimized in terms of choice of monomers, porogen, cross-linker and initiator to have the best recognition as possible for targeted molecule. The sorbent obtained was characterized by nitrogen sorption (BET), scanning electron microscopy (SEM) and solid-phase extraction (SPE) to plot adsorption isotherms. The selectivity of polymer between glucosamine and interfering salt as ammonium sulphate was calculated. Extraction procedure was optimized in terms of loading, washing and elution solvents, to have the best recovery of glucosamine. Compounds were analysed by HPLC-UV after chemical derivatization. The results showed that the optimal conditions of extracting glucosamine on this new type of sorbent were as follows: percolation of plant extract in EtOH/aqueous HCl pH 3, washing of cartridge with water and elution of compound of interest with aqueous acetic acid solution at 5%. The recoveries of glucosamine were around 53% and 70%, from aqueous standard solution and aqueous chicory roots extracts, respectively, on the molecularly imprinted polymer. And, only 11% and 7% of the ammonium sulphate were recovered from standard solution and chicory roots extract, respectively. The use of the MIP as solid-phase extraction sorbent was able to extract preferentially glucosamine from structural analogues and ammonium salt. Assays on chicory roots extracts were carried out, and the MIP showed good results allowing the transfer methodology at semi-industrial scale for cosmetic companies. The optimized protocol of extraction of glucosamine allowed using only eco-friendly solvents, as ethanol, water and acetic acid.