Enantiomeric discrimination of aromatic-containing anionic substrates using cationic cyclodextrins

Phosphated cyclodextrins as water-soluble chiral NMR solvating agents for cationic compounds

The utility of phosphated α-, β- and γ-cyclodextrins as water-soluble chiral NMR solvating agents for cationic substrates is described. Two sets of phosphated cyclodextrins, one with degrees of substitution in the 2–6 range, the other with degrees of substitution in the 6–10 range, are examined. Results with 33 water-soluble cationic substrates are reported. We also explored the possibility that the addition of paramagnetic lanthanide ions such as praseodymium(III) and ytterbium(III) further enhances the enantiomeric differentiation in the NMR spectra. The chiral differentiation with the phosphated cyclodextrins is compared to prior results obtained with anionic carboxymethylated cyclodextrins. There are a number of examples where a larger differentiation is observed with the phosphated cyclodextrins.

Expedited Selection of NMR Chiral Solvating Agents for Determination of Enantiopurity

The use of NMR chiral solvating agents (CSAs) for the analysis of enantiopurity has been known for decades, but has been supplanted in recent years by chromatographic enantioseparation technology. While chromatographic methods for the analysis of enantiopurity are now commonplace and easy to implement, there are still individual compounds and entire classes of analytes where enantioseparation can prove extremely difficult, notably, compounds that are chiral by virtue of very subtle differences such as isotopic substitution or small differences in alkyl chain length. NMR analysis using CSAs can often be useful for such problems, but the traditional approach to selection of an appropriate CSA and the development of an NMR-based analysis method often involves a trial-and-error approach that can be relatively slow and tedious. In this study we describe a high-throughput experimentation approach to the selection of NMR CSAs that employs automation-enabled screening of prepared libraries of CSAs in a systematic fashion. This approach affords excellent results for a standard set of enantioenriched compounds, providing a valuable comparative data set for the effectiveness of CSAs for different classes of compounds. In addition, the technique has been successfully applied to challenging pharmaceutical development problems that are not amenable to chromatographic solutions. Overall, this methodology provides a rapid and powerful approach for investigating enantiopurity that compliments and augments conventional chromatographic approaches.

Cyclodextrin assisted enantiomeric recognition of emtricitabine by 19F NMR spectroscopy

A ¹⁹F NMR spectroscopic method using cyclodextrins as chiral recognition agents was developed for the quantitative determination of emtricitabine enantiomers.

Development of curcumin-cyclodextrin/cellulose nanocrystals complexes: New anticancer drug delivery systems

The synthesis of curcumin-cyclodextrin/cellulose nanocrystals (CNCx) nano complexes was performed. CNCx were functionalized by ionic association with cationic β-cyclodextrin (CD) and CD/CNCx complexes were used to encapsulate curcumin. Preliminary in vitro results showed that the resulting curcumin-CD/CNCx complexes exerted antiproliferative effect on colorectal and prostatic cancer cell lines, with IC50s lower than that of curcumin alone.