Efficient extraction of patuletin and quercetagetin from their plant extract using molecularly imprinted polymer based syringe: A green technology

This study demonstrates the development of a molecularly imprinted solid-phase extraction (MISPE) frit for the easy, rapid, and straightforward extraction of two medicinally important flavonoids, patuletin (PL) and quercetagetin (QTG). The extraction beds based on molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were synthesized through bulk polymerization, employing 2-vinyl pyridine as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent. The synthesized polymers were characterized using various analytical techniques, including scanning electron microscope (SEM), Fourier transform infrared (FT-IR), Brunauer-Emmett-Teller (BET), and thermogravimetric analysis (TGA). The adsorption performance of the PL-imprinted polymer (PL-MIP) and NIP was evaluated through batch rebinding experiments. Multiple theoretical models, such as Langmuir, Freundlich, Scatchard, LF-isotherm, and kinetic models, were applied to gain insights into the adsorption behavior. PL-MIP exhibited a significantly higher binding capacity for PL, reaching 38 mg/g compared to only 8 mg/g for the NIP, yielding an imprinting factor of 4.7. Furthermore, the PL-MIP demonstrated a strong affinity for QTG, a structurally similar compound. Competitive binding studies confirmed that the PL-MIP exhibited selective recognition for PL and QTG over other structurally similar analogs, affirming the presence of specific binding sites for the target molecules. The experimental conditions were optimized by adjusting the washing solvent (deionized water) and the elution solvent (ethanol) in terms of volume and elution time. Finally, a syringe, Polytetrafluoroethylene (PTFE) membrane, and the PL-MIP were successfully incorporated for the preparation of a specialized frit to selectively extract and enrich PL and QTG from methanolic extracts of Tagetes patula and Tagetes erecta, respectively. The developed MISPE system proved to be a more efficient, reliable, and effective alternative to conventional extraction techniques, facilitating the selective isolation of PL and QTG from complex plant matrices. Additionally, the approach is green owing to significantly less use of solvents and energy-intensive equipment, and has the potential to be extended to enrich any compound of interest from its natural resource.