Leandro Bandeira Borré

Two new long-chain N-alkyl imidazole derivatives, 2-(1-octadecyl-imidazol-2-yl)pyridine and 2-(furan-2-yl)-1-(octadecane-1-yl)-1H-imidazole, were synthesized via the Radziszewski reaction followed by N-alkylation. This is the first report of furan-imidazole obtained by this route using furfuraldehyde as a renewable biomass-derived precursor. FTIR, 1D/2D solution NMR, and HRMS confirmed the structural elucidation, while XRD and solid-state ¹³C CPMAS NMR corroborated the crystal structures of the precursors. Notably, previously misassigned ¹H and ¹³C chemical shifts reported in the literature for pyridine and furan-imidazole precursors were corrected. Furthermore, ¹³C CPMAS NMR spectra of those precursors are reported here for the first time. These findings expand the scope of the Radziszewski reaction and provide new insights into the structural characterization of imidazole-based systems.

Mefloquine (MQ) is an antimalarial medication prescribed to treat or malaria prevention.. When taken by children, vomiting usually occurs, and new doses of medication frequently need to be taken. So, developing pediatric medicines using taste-masked antimalarial drug complexes is mandatory for the success of mefloquine administration. The hypothesis that binding mefloquine to an ion-exchange resin (R) could circumvent the drug’s bitter taste problem was proposed, and solid-state ¹³C cross-polarization magic angle spinning (CPMAS) NMR was able to follow MQ–R mixtures through chemical shift and relaxation measurements. The nature of MQ–R complex formation could then be determined. Impedimetric electronic tongue equipment also verified the resinate taste-masking efficiency in vitro. Variations in chemical shifts and structure dynamics measured by proton relaxation properties (e.g., T1ρ^H) were used as probes to follow the extension of mixing and specific interactions that would be present in MQ–R. A significant decrease in T1ρ^H values was observed for MQ carbons in MQ–R complexes, compared to the ones in MQ (from 100–200 ms in MQ to 20–50 ms in an MQ–R complex). The results evidenced that the cationic resin interacts strongly with mefloquine molecules in the formulation of a 1:1 ratio complex. Thus, ¹³C CPMAS NMR allowed the confirmation of the presence of a binding between mefloquine and polacrilin in the MQ–R formulation studied.

In this study, we have used various techniques to characterize the spectroscopic and thermal behavior of Pyrantel Pamoate (PP), an anthelmintic drug classified as an essential drug by the World Health Organization for the treatment of parasitic worm infections, as powder X-ray Diffraction (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Solid State NMR (13C CPMAS NMR), thermogravimetric analysis (TG), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC) at two different heating rates (2 and 10 K.min-1) under an inert gas flow. We analyzed a USP standard sample of PP, which allowed us to characterize it. Additionally, we examined four commercial solid formulations of PP purchased from Colombian pharmacies to provide evidence of any potential contaminants or adulteration. Our results confirmed the authenticity of the standard sample and identified PP as the active ingredient in all four Colombian products. By combining these analytical techniques, we were able to provide a comprehensive characterization of PP and potential issues with commercial formulations.