Molecularly imprinted polymers for selective extraction of synephrine from Aurantii Fructus Immaturus

In this work, molecularly imprinted solid-phase extraction (MISPE) has been used to selectively enrich, purify, or remove synephrine from Aurantii Fructus Immaturus. To this end, a molecularly imprinted polymer (MIP) was prepared by self-assembly from the template synephrine, the functional monomer methacrylic acid, and the crosslinker ethylene glycol dimethacrylate in 1:4:20 molar ratio. Subsequent molecular interrogation of the MIP binding sites revealed preferential structural selectivity for synephrine relative to other structurally related naturally occurring compounds (i.e. octopamine and tyramine ). This selectivity was subsequently exploited to achieve substantial sample clean-up of extracts of crude Aurantii Fructus Immaturus and Aurantii Fructus Immaturus stir-baked with bran. The purity of synephrine in the extracts after MISPE represented approximately 24.21-fold enrichment of the synephrine in the untreated extracts of Aurantii Fructus Immaturus stir-baked with bran. High recoveries (85–90%) from the samples proved that the method was valid for selective enrichment, purification, or removal of synephrine from Aurantii Fructus Immaturus.