Comprehensive Study of the Selective Binding of Mitragynine Using Dummy Template Molecularly Imprinted Polymers

Mitragyna speciosa (Korth.), commonly known as kratom, contains a variety of secondary metabolites, with mitragynine, an indole alkaloid, being the most significant due to its analgesic properties. However, the limited commercial availability of mitragynine standards highlights the need for effective separation techniques. The complexity of kratom’s plant matrix makes selective isolation of mitragynine challenging. This study investigates the use of dummy template molecularly imprinted polymers (MIPs) as selective sorbents for isolating mitragynine. Colchicine was selected as a promising dummy template molecule for mitragynine. Prepolymerization studies, including association constant and Job plot analysis, identified methacrylic acid in methanol as the optimal component for synthesis. MIP synthesis was optimized using the bulk polymerization method with a template-monomer-crosslinker ratio of 1:3:20, at 80°C for 24 hours. Template removal was achieved through sonication, employing a 16-cycle methanol, and infrared spectroscopy confirmed successful template removal. MIP adsorption followed a pseudo-second-order kinetic model and a Langmuir isotherm. Kratom extraction was performed using the reflux method with methanol. Separation of mitragynine was conducted via column chromatography with MIP as the sorbent, resulting in enhanced mitragynine isolation. Quantitative analysis showed that the MIP method achieved an isolation efficiency of 36.7%, whereas preparative thin-layer chromatography (PTLC) yielded only 3.607%. Meanwhile, visual observations using Thin-Layer Chromatography (TLC) demonstrated that MIP produced a cleaner chromatogram compared to conventional PTLC. These findings suggest that MIPs offer a promising alternative to conventional separation techniques for isolating mitragynine from complex plant extracts.