Kinetics and thermodynamics of the formation of inclusion complexes between cyclodextrins and DNA-intercalating agents. Inclusion of ellipticine in γ-cyclodextrin

Chahine, Jean Michel El Hage; Bertigny, Jean-Pierre; Schwaller, M. A.

doi:10.1039/p29890000629

Cited by 24 publications

(39 citation statements)

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“…The complexes ellipticine/modified-␤-CD give emission maxima at 450-460 nm but also exhibit a shoulder near 500 nm. On the other hand for ␥-CD the emission maximum appears at 480 nm in agreement with the spectra described by Schwaller (El Hage Chahine et al, 1989). In all cyclodextrins studied an increase in the fluorescence intensity is observed also at this pH value when the CD concentration is increased.…”

supporting

confidence: 80%

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Association Characteristics of the Inclusion Complexes, Neutral Ellipticine/Cyclodextrins

Sbai

Lyazidi

Lerner

et al. 1997

Biomed. Chromatogr.

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supporting

confidence: 80%

“…Inclusion of ellipticine in ␥-CD (El Hage Chahine et al, 1989) or in modified ␤-CD (Sbai et al, 1995) increases the hydrosolubility and hence the overall fluorescence intensity of ellipticine. The possibility of inclusion of cationic species which predominate in aqueous solutions is questioned because these species are water-soluble.…”

mentioning

confidence: 98%

Association Characteristics of the Inclusion Complexes, Neutral Ellipticine/Cyclodextrins

Sbai

Lyazidi

Lerner

et al. 1997

Biomed. Chromatogr.

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“…As for the (SA)aLfbH species, its presence in the medium is thermodynamically very underprivileged because the deprotonation pK,, for the (SA)Lfb centre (Eqns 13 and 15) would be lower than that the pK,, of the (SA)aLf centre (Eqns 12,14 and 16). In this case, the fluorescence intensity should obey Eqn (17) (El Hage Chahine and Dubois, 1983;El Hage Chahine et al, 1989). which relates the fluorescence intensity to the concentration of the H(SA)aLfb species.…”

Section: Discussionmentioning

confidence: 99%

Transferrin

Pakdaman

Chahine

1997

European Journal of Biochemistry

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The interaction of apolactoferrin with hydrogen carbonate (bicarbonate) has been investigated in the pH range 6.5-9.2. In the absence of bicarbonate apolactoferrin loses a single proton with pK,, of 8.10. This proton loss is independent of the interaction with the synergistic anion. The C-site of apolactoferrin interacts with bicarbonate with a very low affinity (K;' = 3.2 M-'). This process is accompanied by a proton loss, which is probably provided by the bicarbonate in interaction with the protein. This proton loss can possibly be the result of a shift in the proton dissociation constant, pK,, of the bicarbonate/ carbonate acid/base equilibrium, which would decrease from pK, 10.35 to pK,, 6.90 in the bicarbonatelactoferrin adduct. The N-site of the protein interacts with bicarbonate with an extremely low affinity, which excludes the presence of the N-site-synergistic anion adduct in neutral physiological media. Contrary to serum transferrin, the concentration of the apolactoferrin in interaction with bicarbonate is pH dependent. Between pH 7.4 and pH 9 with [HCO,] about 20 mM, the concentration of the serum transferrin-bicarbonate adduct is always about 30 %, whereas that of the apolactoferrin-synergistic anion adduct varies from 25% at pH 7.5 to 90% at pH 9. This implies that, despite an affinity for bicarbonate two orders of magnitude lower than that of serum transferrin, lactoferrin interacts better with the synergistic anion. This can be explained by the possible interaction of lactoferrin with carbonate in neutral media, whereas transferrin only interacts with bicarbonate.Keywords; transferrin ; lactoferrin; synergistic anion ; iron metabolism; iron transport.The transferrin family constitutes the most important irontransport system in vertebrates and in some invertebrates, mainly worms and insects (Aisen, 1989;Kurama et al., 1995). These proteins transport iron from the biological fluid into the cytoplasm via the plasma membrane by receptor-mediated endocytosis. With the exception of melanotransferrin, which is overexpressed in melanocytes, the other transferrins of the family are soluble glycoproteins (Baker and Lindley, 1992). These are represented by serum transferrin, responsible for iron transport in mammals, egg white ovotransferrin and milk lactoferrin, which is also present in tears, genital secretion, seminal fluid, sweat, etc. (Aisen, 1989). In addition to their iron-transport function, some transferrins, such as lactoferrins, are involved in the immune response and are bactericidal and bacteriostatic (FurmanCorrespondence to J

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“…Potential alternatives to quaternization include the use of cyclodextrins or the use of micellar media. An inclusion complexe between γ-CD and ellipticine was characterized by El Hage Chahine et al after a very thorough study [136]. A (1:2) complex involving the neutral form is described; however the ellipticinium form of the drug is not complexed.…”

Section: Enhancement Of the Fluorescence Of Guests Molecules In Cyclomentioning

confidence: 99%

Luminescence in organized media and supramolecular interactions:physicochemical aspects and applications

Lerner¹,

Martín²

2000

Analusis

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Introduction Molecular luminescence of analytes in organized media or in supramolecular complexes of cyclodextrinsThe photophysical and photochemical behaviour of molecules complexed to cyclodextrins (CD) is generally different from their behaviour in solution. The first observations in the field were qualitative and were related to the increased stabilisation of labile molecules, mostly drugs, against photodegradation when complexed to natural cyclodextrins [1]. Complexation by CD's was then the preferred subject for those involved in supramolecular chemistry and drug vectorisation techniques [2] as well as in separation techniques [3][4][5]. Stabilization of a molecule against photochemical degradation is still very important in the field of pharmaceutical sciences. A recent example is the stabilisation of promazine as an inclusion complex with β-cyclodextrin [6]. Other photochemists were attracted quite early to this field of research and initiated studies, which were mostly photophysical in nature [7,8]. The key observation was that the formation of supramolecular complexes of analytes with cyclodextrins (CDs) resulted in an increase of their fluorescence quantum yield or even in the appearance of room temperature phosphorescence (RTP) [9][10][11][12]. This enhancement has been used to increase the sensitivity and the selectivity in both luminescence and chromatographic techniques [13-15].We will not say more about RTP with CDs as the subject will be developed in another contribution in the same issue of this Journal. However RTP is also observed in the solubilization of analytes in micellar colloïdal solutions and this field will be reviewed hereunder.These properties have been used to develop analytical techniques, which combine the selectivity of complexation with an enhanced emission [16][17][18][19]. In this way an improvement in the detection limits is obtained in many separation techniques such as HPLC, capillary electrophoresis (CE) or planar chromatography. Furthermore these molecular interactions allow to reveal or to stabilize new molecular forms or to turn species which are normally non-emitting into luminescent ones. All these aspects are reviewed hereunder after a short summary on the nature of the intermolecular interactions, which lie at the heart of these effects. Nature of the interactions between an analyte and a CD or a micelleWithout going into a thorough analysis of the origin of the interactions which exist between molecules in dense media which concern us here, it seems useful to recall the most important factors which should be taken into account when any type of luminescence, fluorescence or phosphorescence is involved.

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Kinetics and thermodynamics of the formation of inclusion complexes between cyclodextrins and DNA-intercalating agents. Inclusion of ellipticine in γ-cyclodextrin

Cited by 24 publications

References 1 publication

Association Characteristics of the Inclusion Complexes, Neutral Ellipticine/Cyclodextrins

Association Characteristics of the Inclusion Complexes, Neutral Ellipticine/Cyclodextrins

Transferrin

Luminescence in organized media and supramolecular interactions:physicochemical aspects and applications

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