NMR Studies of Cyclodextrin Inclusion Complex with Ethyl Hexanoate in Ethanol Solution

Matsui, Toshiro; Iwasaki, H.; Matsumoto, Kiyoshi; Osajima, Yutaka

doi:10.1271/bbb.58.1102

Cited by 10 publications

(7 citation statements)

References 4 publications

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“…It can be stated that for five of the volatile compounds a maximal retention of 1 mol of aroma is reached even in the presence of a large excess of aroma before freeze-drying (4 mol/mol of β-CD). For ethyl propionate, ethyl hexanoate, hexanoic acid, and hexanol this maximal retention is in agreement with NMR results published on the structure of their β-CD complexes showing that their carbon chain is included in the β-CD cavity ( , ). It seems also that the only aroma molecules retained during freeze-drying are those encapsulated into the β-CD cavity, whereas the others are unable to interact in a sufficient way with the carrier.…”

Section: Resultssupporting

confidence: 91%

Competitive Binding of Aroma Compounds by β-Cyclodextrin

Goubet

Dahout

Sémon

et al. 2001

J. Agric. Food Chem.

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Retention of six aroma compounds has been studied after dehydration of ternary mixtures of aroma water and beta-cyclodextrin. A maximal retention of a mole of aroma per mole of beta-cyclodextrin has been observed for five of the aroma compounds, whereas retention of benzyl alcohol can be twice as high. Retention of a mixture of aroma compounds has also been studied. It has been noted that when volatile compounds compete for the same binding sites on beta-cyclodextrin, ethyl hexanoate, 2-methylbutyric acid, and benzyl alcohol are, respectively, better retained than ethyl propionate, hexanoic acid, and hexanol. Preferential retention observed with esters can be simply explained by their difference of physicochemical properties, but for the acids and alcohols a study at the molecular scale has been necessary. The better retention of 2-methylbutyric acid can be explained by differences in the nature of interaction between the acids and their carrier. At least selectivity of retention noted for the alcohol could be due to a difference in the location of the guest and also a difference in the number of aroma molecules that can be bound per polysaccharide molecule.

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Section: Resultssupporting

confidence: 91%

Competitive Binding of Aroma Compounds by β-Cyclodextrin

Goubet

Dahout

Sémon

et al. 2001

J. Agric. Food Chem.

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“…Therefore, the drug and βCD were dissolved in DMSO-d6 as both βCD and UC781 have a high degree of solubility in this solvent. In addition, the relative magnitude of the dielectric constants of DMSO and H 2 O (ɛ=46.8 and 80, respectively) are similar; therefore, the essential feature of the interaction of UC781 with βCD in DMSO should be similar to that in water (17,31). Our 2D ROESY results, considered together with the phase solubility, UV and FTIR spectroscopic, and DSC data, indicate that the benzyl ring of UC781 is included into the cyclodextrin hydrophobic cavity while the N-H group of the thioamide functionality interacts with OH2 and OH3 of βCD on the primary side.…”

Section: D Roesy Nmr Spectroscopy Of Uc781/cyclodextrin Complexesmentioning

confidence: 98%

Characterization of Cyclodextrin Inclusion Complexes of the Anti-HIV Non-Nucleoside Reverse Transcriptase Inhibitor UC781

Yang

Parniak

Isaacs³

et al. 2008

AAPS J

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Abstract. The highly potent anti-HIV agent UC781 is being evaluated for use in topical microbicides to prevent HIV transmission. However, UC781 is extremely hydrophobic with poor water solubility, a property that may complicate appropriate formulation of the drug. In this study, we examined the ability of several cyclodextrins, beta-cyclodextrin (βCD), methyl-beta-cyclodextrin (MβCD), and 2-hydroxylpropyl-beta-cyclodextrin (HPβCD), to enhance the aqueous solubility of UC781. Each of the cyclodextrins provided dramatic increases in UC781 aqueous solubility, the order being MβCD>HPβCD>βCD. The complexation constants (K 1:1 ) of the inclusion complexes were determined via a phase solubility technique using high-performance liquid chromatography and showed that UC781 solubility increased linearly as a function of cyclodextrin concentration. Ultraviolet spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and 2D 1 H ROESY NMR spectroscopy were used to further characterize these UC781/cyclodextrin complexes. The inhibitory potency of UC781 and its HPβCD inclusion complex were evaluated using an in vitro HIV-1 reverse transcriptase inhibition assay The inhibitory potency of the UC781/HPβCD complex was 30-fold greater than that of UC781 alone, showing that the complexed drug is able to provide substantial inhibition of its target. The enhancement of UC781 aqueous solubility is essential for the development of a useful vaginal microbicide dosage form, and our data suggest that UC781/cyclodextrin inclusion complexes may be useful in this context.

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“…21 It should be noted that this reported NMR work on catechin-b-CD complex required no DMSO cosolvent because the flavonoid is water-soluble, and the close similarity in b-CD-induced proton shift changes between (þ)- catechin and quercetin would imply that the added DMSO, though capable of reducing the binding strength of the quercetin-b-CD complex in water (possibly via binding competition or quercetin extraction), will not significantly alter the basic mode of interaction. 24,25 Based on the results of NMR and stability studies, it can be inferred that the B-ring, C-ring, and at least part of the A-ring of quercetin (except C6) exhibit significant interaction with the hydrophobic b-CD cavity.…”

Section: H-nmr Spectroscopic Analysismentioning

confidence: 99%