• Journal of Pharmaceutical Investigation
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• 제30권1호
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• pp.33-37
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• 2000

One of the methods to increase the solubility of a drug is to use complexation with a cyclodextrin. Due to the hydrophobic nature of the interior cavity of the cyclodextrin, it has been known that undissociated lipophilic drugs can be included within the cyclodextrin by hydrophobic interaction. Recently, inclusion of hydrophilic or dissociated form of a drug has been investigated. In this study, the synergism of pH and complexation with $hydroxypropy-{\beta}-cyclodextrin\;(HP\;{\beta}\;CD)$ to increase the solubility of two oxicam derivatives was investigated. In addition, the effect of partition coefficient of dissociated and undissociated form of the drug on the extent of complexation with HP ${\beta}$ CD was studied. The solubility was measured by equilibrium solubility method. The solubility of tenoxicam and piroxicam increased exponentially with an increase in solution pH above the pKa of the drug in the presence and absence of HP ${\beta}$ CD. The solubility of the drugs increased linearly as a function of HP ${\beta}CD$ concentration at fixed pH. Although the stability constant of ionized species is less than that of the unionized species, the concentration of the ionized drug complex is greater than that of the unionized drug complex due to higher concentration of ionized species at pH 7.3.

• Mass Spectrometry Letters
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• 제6권1호
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• pp.17-20
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• 2015

Sesamin, one of the lignans in sesame seed, was a labile compound in MS and it was reported that the protonated molecule of sesamin decomposed easily in ES ionization process and it cannot be detected (G. Yan, et al., Rapid Commun Mass Spectrom. 2007, 21, 3613-3620). To protect labile compounds, an amino-cyclodextrin (NCyD) was added to the sample to promote the host-guest interaction complex in ESI-MS. As a result, sesamin was ionized as the NCyD-sesamin-NCyD (1:2) complex without undesired decomposition, suggesting that the amino-CyDs assist the ionization of the labile molecules capped with CyDs by host-guest interaction and these compounds were ionized without their decomposition, those are like amino-CyD complex-assisted ionization. The amino-CyD complexes of sesamin and sesamolin were also analyzed by their ion-mobility MS.

• Macromolecular Research
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• 제14권4호
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• pp.449-455
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• 2006

Ionic cluster mimic, polymer electrolyte membranes were prepared using polymer composites of crosslinked poly(vinyl alcohol) (PVA) with sulfated-${\beta}$-cyclodextrins (${\beta}-CDSO_3H$) or phosphated-${\beta}$-cyclodextrins (${\beta}-CDPO(OH)_2$). When Nafion, developed for a fuel cell using low temperature, polymer electrolyte membranes, is used in a direct methanol fuel cell, it has a methanol crossover problem. The ionic inverted micellar structure formed by micro-segregation in Nafion, known as ionic cluster, is distorted in methanol aqueous solution, resulting in the significant transport of methanol through the membrane. While the ionic structure formed by the ionic sites in either ${\beta}-CDSO_3H$ or ${\beta}-CDPO(OH)_2$ in this composite membrane is maintained in methanol solution, it is expected to reduce methanol transport. Proton conductivity was found to increase in PVA membranes upon addition of ionized cyclodextrins. Methanol permeability through the PVA composite membrane containing cyclodextrins was lower than that of Nafion. It is thus concluded that the structure and fixation of ionic clusters are significant barriers to methanol crossover in direct methanol fuel cells.

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1409-1412
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• 2014

Sex hormones are important metabolites in vertebrates' development and reproduction. For rapid screening sex hormones, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is one of the promising analytical platforms, but MALDI MS faces many challenges in detecting steroids such as low ionization efficiency and matrix background interference. One potential strategy to overcome matrix interference in the low m/z region is using a cyclodextrin (CD)-supported matrix for steroid analysis since CD-supported matrixes are known to effectively suppress matrix-related ion signals. In this study, we aimed to find the optimal CD-supported matrix for the analysis of the nonderivatized sex steroids. Our results showed that the ${\alpha}CD$-supported 2,5-dihydroxybenzoic acid (DHB) matrix efficiently ionized all three major classes of sex hormones, estrogens, androgens, and progestagens, with low or no matrix background and also with high sensitivity. In addition, the ${\alpha}CD$-supported DHB matrix mainly generated molecular ions or protonated ions of sex hormones, and this enabled us to obtain information-rich tandem mass spectra which potentially lead to unambiguous identification of steroid species from complex metabolite mixtures.