Spectroscopic (fluorescence, 1D-ROESY) and theoretical studies of the thiabendazole and β-cyclodextrin inclusion complex

Alexandrino, Guilherme L.; Calderini, Adriana; Morgon, Nelson H.; Pessine, Francisco Benedito Teixeira

doi:10.1007/s10847-012-0150-8

Cited by 6 publications

(6 citation statements)

References 18 publications

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“…In order to evaluate the interaction between Que and CDs, fluorescence spectroscopy was performed. The fluorescence signal of a small molecule can be modified upon the encapsulation in the cavity of a supramolecule such as CD. , The spectroscopic behavior of Que was investigated by adding increasing concentrations of either HP-β-CD or Me-β-CD into a solution of Que at a stable concentration.…”

Section: Resultsmentioning

confidence: 99%

Preparation and Biophysical Characterization of Quercetin Inclusion Complexes with β-Cyclodextrin Derivatives to be Formulated as Possible Nose-to-Brain Quercetin Delivery Systems

et al. 2020

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Quercetin (Que) is a flavonoid associated with high oxygen radical scavenging activity and potential neuroprotective activity against Alzheimer's disease. Que's oral bioavailability is limited by its low water solubility and extended peripheral metabolism; thus, nasal administration may be a promising alternative to achieve effective Que concentrations in the brain. The formation of Que−2-hydroxypropylated−β-cyclodextrin (Que/HP-β-CD) complexes was previously found to increase the molecule's solubility and stability in aqueous media. Que−methyl−β-cyclodextrin (Que/Me-β-CD) inclusion complexes were prepared, characterized, and compared with the Que/HP-β-CD complex using biophysical and computational methods (phase solubility, fluorescence and NMR spectroscopy, differential scanning calorimetry (DSC), and molecular dynamics simulations (MDS)) as candidates for the preparation of nose-to-brain Que's delivery systems. DSC thermograms, NMR, fluorescence spectroscopy, and MDS confirmed the inclusion complex formation of Que with both CDs. Differences between the two preparations were observed regarding their thermodynamic stability and inclusion mode governing the details of molecular interactions. Que's solubility in aqueous media at pH 1.2 and 4.5 was similar and linearly increased with both CD concentrations. At pH 6.8, Que's solubility was higher and positively deviated from linearity in the presence of HP-β-CD more than with Me-β-CD, possibly revealing the presence of more than one HP-β-CD molecule involved in the complex. Overall, water solubility of lyophilized Que/Me-β-CD and Que/HP-β-CD products was approximately 7−40 times and 14−50 times as high as for pure Que at pH 1.2−6.8. In addition, the proof of concept experiment on ex vivo permeation across rabbit nasal mucosa revealed measurable and similar Que permeability profiles with both CDs and negligible permeation of pure Que. These results are quite encouraging for further ex vivo and in vivo evaluation toward nasal administration and nose-to-brain delivery of Que.

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Section: Resultsmentioning

confidence: 99%

Preparation and Biophysical Characterization of Quercetin Inclusion Complexes with β-Cyclodextrin Derivatives to be Formulated as Possible Nose-to-Brain Quercetin Delivery Systems

et al. 2020

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“…The aggregates of C 16 TPB@2b-CD, as consistent building blocks, can construct bilayer membranes at the appropriate concentration [43]. However, surface tension measurements revealed that there were two kinds of inclusion formations having 1:1 and 1:2 stoichiometry for b-CD-[C 12 MIM]PF 6 and that only the tails of [C 12 MIM]PF 6 were incorporated into the b-CD cavity. Hydrophobicity played a crucial role in supporting the formation of b-CD-[C 12 MIM]PF 6 inclusion complexes, and hydrogen bonding was responsible for maintaining the channel structure [39].…”

Section: Stoichiometry and Inclusion Constantmentioning

confidence: 99%

“…An interesting feature of the emission spectra is the shift of the emission maximum toward a longer wavelength with increasing excitation wavelength [45]. For neat [C 4 MIM][PF 6 ], the estimated value of the fluorescence quantum yield (k exc = 360 nm) is about 5 Â 10 À3 , and the major component ($90%) of the decay consists of a lifetime in the range of 470-590 ps [44]. At the maximum excitation wavelength of 276 nm, no changing phenomena were observed for the emission maxima shape at ca.…”

Section: Interactions Between Ionic Liquids and B-cdmentioning

confidence: 99%

“…In contrast, b-CD has a hydrophilic exterior because of hydroxyl gathering at the lateral border of the CD molecule [2,3]. Because of these properties, b-CD can enhance the fluorescence intensities (FIs) of many compounds with weak fluorophores [4][5][6]. The cavity can incorporate nonpolar molecules as guests to form inclusion complexes by van der Waals forces.…”

Section: Introductionmentioning

confidence: 99%

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The joint effects of room temperature ionic liquids and ordered media on fluorescence characteristics of estrogens in water and methanol

Wang

Duan

Dahlgren

et al. 2014

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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h i g h l i g h t sBoth b-CD and CTAB could sensitize the fluorescence of EE2 and E2. Inclusion ratio of the complex was 1:1. Typical RTILs including [C n MIM]BF 4 and [C n MIM]PF 6 (n = 4, 6). The fluorescence lifetimes were 2.50-2.53 and 4.03-4.13 ns for EE2 and E2. The quenching process was demonstrated to be a dynamic quenching mechanism. g r a p h i c a l a b s t r a c tThe fluorescence lifetimes of EE2 were 2.50 and 4.13 ns, respectively, in water and methanol, and they increased gradually with increasing of b-CD concentrations. a r t i c l e i n f o t r a c tThis study investigated the steady-state and time-resolved fluorescence properties of 17a-ethinylestradiol (EE2) and 17b-estradiol (E2) in the presence of ordered media (b-cyclodextrins (b-CD) and cetyltrimethylammonium bromide (CTAB)). In addition, we analyzed the effects of four room temperature ionic liquids (RTILs) on the fluorescence intensities (FIs) of EE2/b-CD and E2/b-CD inclusion complexes in methanol. Both b-CD and CTAB enhanced the fluorescence of EE2 and E2. The FIs of EE2 and E2 with b-CD or CTAB in methanol were greater than those in water, possibly resulting from decreased oxygen-quenching in H 2 O molecules. b-CD and CTAB may form inclusion complexes with estrogen in both water and methanol. The inclusion ratio of the complex was 1:1 and the inclusion constant (K) values in water were greater than those in methanol. The fluorescence lifetimes were 2.50 and 4.13 ns for EE2 and 2.58 and 4.03 ns for E2 in aqueous solution and methanol, respectively. The changing trend of fluorescence lifetimes for EE2 and E2 in b-CD or CTAB was similar to the steady-state FIs. The four RTILs had a significant quenching effect on the FIs of EE2/b-CD and E2/b-CD, and the quenching process for EE2/ b-CD and E2/b-CD by RTILs was demonstrated to be a dynamic quenching mechanism. Fluorescent data obtained from these complex systems provide a theoretical foundation for understanding the interaction mechanisms between ordered media and RTILs in the analysis of estrogens.

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“…[7][8][9][10][11] Some irregular energy differences in the interactions between enantiomers and selectors were found by using various molecular modeling methods. [12][13][14][15][16][17] Nevertheless, because of the computational limitations of low levels of theory, or the non-quantitative nature of theoretical studies with respect to qualitative analyses, the results of previous studies could only be used to interpret the mechanism of enantiomeric separation, but could not be used to predict the possibility of separation before the CE experiment.…”

Section: Introductionmentioning

confidence: 99%

Quantitative prediction of enantioseparation using β-cyclodextrin derivatives as chiral selectors in capillary electrophoresis

Guo

Wang

Zuo

et al. 2014

Analyst

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β-Cyclodextrin derivatives as chiral selectors are becoming increasingly important for enantioseparations in capillary electrophoresis (CE). Nevertheless, there are some enormous challenges in choosing effective selectors from a variety of compounds, and up to now no systematic quantitative studies for predicting the possibility of enantiomeric separation before CE experiments have been reported. In this paper, in order to resolve previous confusions, we investigated the enantioseparations of ten chiral drugs using a method of combining experiments with theoretical calculations. MMFF, PM3, DFT and ONIOM2 methods were simultaneously utilized during the course of our computer simulations. The results indicated that a specific value of greater than or approximately equal to 6 kJ mol(-1) for the interaction energy difference (ΔΔE) between a pair of enantiomers with a selector is required in order to achieve enantiomeric separation. This discovery offers a meaningful reference to predict enantiomeric separations, so as to design and synthesize some more efficient chiral selectors.

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Spectroscopic (fluorescence, 1D-ROESY) and theoretical studies of the thiabendazole and β-cyclodextrin inclusion complex

Cited by 6 publications

References 18 publications

Preparation and Biophysical Characterization of Quercetin Inclusion Complexes with β-Cyclodextrin Derivatives to be Formulated as Possible Nose-to-Brain Quercetin Delivery Systems

Preparation and Biophysical Characterization of Quercetin Inclusion Complexes with β-Cyclodextrin Derivatives to be Formulated as Possible Nose-to-Brain Quercetin Delivery Systems

The joint effects of room temperature ionic liquids and ordered media on fluorescence characteristics of estrogens in water and methanol

Quantitative prediction of enantioseparation using β-cyclodextrin derivatives as chiral selectors in capillary electrophoresis

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