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A High-Resolution Magic Angle Spinning NMR Study of the Enantiodiscrimination of 3,4-Methylenedioxymethamphetamine (MDMA) by an Immobilized Polysaccharide-Based Chiral Phase

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ABSTRACT

This paper reports the investigation of the chiral interaction between 3,4-methylenedioxy-methamphetamine (MDMA) enantiomers and an immobilized polysaccharide-based chiral phase. For that, suspended-state high-resolution magic angle spinning nuclear magnetic resonance spectroscopy (1H HR-MAS NMR) was used. 1H HR-MAS longitudinal relaxation time and Saturation Transfer Difference (STD NMR) titration experiments were carried out yielding information at the molecular level of the transient diastereoisomeric complexes of MDMA enantiomers and the chiral stationary phase. The interaction of the enantiomers takes place through the aromatic moiety of MDMA and the aromatic group of the chiral selector by π-π stacking for both enantiomers; however, a stronger interaction was observed for the (R)-enantiomer, which is the second one to elute at the chromatographic conditions.

No MeSH data available.


Graphic of STD amplification factor (mean n = 3) versus concentration of enantiomer at 3.0 s of saturation time.(A) (S)-MDMA and (B) (R)-MDMA.
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pone.0162892.g008: Graphic of STD amplification factor (mean n = 3) versus concentration of enantiomer at 3.0 s of saturation time.(A) (S)-MDMA and (B) (R)-MDMA.

Mentions: Chromatographic chiral recognition is a result of energy differences between the formations of the two transient diastereomeric complexes. Conceptually, it is similar to enantiomeric differentiation in biological process [18]. STD experiments have been commonly employed to determine KD values of the protein-ligand complexes by measuring the equilibrium concentration of the free and bound species [19]. The isotherms fitted from the STD experiments (Fig 8) for both enantiomers were used to calculate KD; from these experiments, it was possible to estimate the equilibrium constants (Kon/Koff) involved in the formation of the transient diastereoisomeric complex of (R)-MDMA and CSP-ID. It is important to note that the STD NMR titrations are strongly dependent of experimental conditions such as the, saturation time, relative concentration of the species, and monitored protons [19].


A High-Resolution Magic Angle Spinning NMR Study of the Enantiodiscrimination of 3,4-Methylenedioxymethamphetamine (MDMA) by an Immobilized Polysaccharide-Based Chiral Phase
Graphic of STD amplification factor (mean n = 3) versus concentration of enantiomer at 3.0 s of saturation time.(A) (S)-MDMA and (B) (R)-MDMA.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036802&req=5

pone.0162892.g008: Graphic of STD amplification factor (mean n = 3) versus concentration of enantiomer at 3.0 s of saturation time.(A) (S)-MDMA and (B) (R)-MDMA.
Mentions: Chromatographic chiral recognition is a result of energy differences between the formations of the two transient diastereomeric complexes. Conceptually, it is similar to enantiomeric differentiation in biological process [18]. STD experiments have been commonly employed to determine KD values of the protein-ligand complexes by measuring the equilibrium concentration of the free and bound species [19]. The isotherms fitted from the STD experiments (Fig 8) for both enantiomers were used to calculate KD; from these experiments, it was possible to estimate the equilibrium constants (Kon/Koff) involved in the formation of the transient diastereoisomeric complex of (R)-MDMA and CSP-ID. It is important to note that the STD NMR titrations are strongly dependent of experimental conditions such as the, saturation time, relative concentration of the species, and monitored protons [19].

View Article: PubMed Central - PubMed

ABSTRACT

This paper reports the investigation of the chiral interaction between 3,4-methylenedioxy-methamphetamine (MDMA) enantiomers and an immobilized polysaccharide-based chiral phase. For that, suspended-state high-resolution magic angle spinning nuclear magnetic resonance spectroscopy (1H HR-MAS NMR) was used. 1H HR-MAS longitudinal relaxation time and Saturation Transfer Difference (STD NMR) titration experiments were carried out yielding information at the molecular level of the transient diastereoisomeric complexes of MDMA enantiomers and the chiral stationary phase. The interaction of the enantiomers takes place through the aromatic moiety of MDMA and the aromatic group of the chiral selector by π-π stacking for both enantiomers; however, a stronger interaction was observed for the (R)-enantiomer, which is the second one to elute at the chromatographic conditions.

No MeSH data available.