Download Investigation of Orientational Isomers of Cyclodextrin Inclusion

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Differentiating geometrical isomers
of retinoids and controlling their
photo-isomerization by
complexation with cyclodextrins
Analytica Chimica Acta 468 (2002) 161-170
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Cyclodextrins
Cyclic oligosaccharides
Composed of D(+)glucopyranose units
Hollow, torus-shape cavity
Cylinders with a hydrophilic exterior and a
hydrophobic interior
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Cyclodextrins
Different types:
α-cyclodextrin : six sugar ring molecules
β-cyclodextrin : seven sugar ring molecules
γ-cyclodextrin : eight sugar ring molecules
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Structure of α-CD
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Structure of γ-CD
Structure of β-CD
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Cyclodextrins
They form inclusion complexes with a
variety of molecules.
Insertion of a hydrophobic guest in aqueous
solutions of cyclodextrins leads to
complexation which no covalent bonds are
broken or formed.
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Applications of Cyclodextrins in Drug
delivery technology
To improve the physical and chemical
properties of drugs
To reduce the side effects of drugs
To enhance the bio-availibility of poorly
soluble drugs
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Applications of Cyclodextrins in Food
industry
To stabilize flavors and fragrances
To mask undesired tastes in the food and
cosmetic industries
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Applications of Cyclodextrins Chemistry
Separation techniques HPLC and …
Increasing the solubility and the stability of
the analytes and therefore sensitivity of
the detection of these analytes
Increasing or decreasing the rate of a
variety of reactions
…
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Retinoids
Very significant biological molecules due to
:
- Their role in the vision process (retinal)
- As vitamins (retinol and its esters)
- Their influence in the cell growth (retinoic
acid , …)
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All trans retinal
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H-NMR spectra of the pure β-CD solution
(C=1.0 x 10-2 M)
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H-NMR spectra of the complex of all-trans-retinal/β-CD at
concentrations 4.0 x 10-3 and 1.0 x 10-2 M respectively.
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Chemical shifts in H-NMR
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Stoichiometry determination
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Association constants determination
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9-Cis retinal
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Effect of the inclusion process on the
photo-isomerization of retinoids
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Ethanolic solution
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All-trans-retinal
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All-trans-retinoic acid
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Thanks
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