Cyclodextrin inclusion effects on fluorescence and fluorimetric properties of the pesticide warfarin

Ishiwata, Shigemasa; Kamiya, Mamoru

doi:10.1016/s0045-6535(97)00006-4

Cited by 26 publications

(17 citation statements)

References 16 publications

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“…10 Karlsson et al Emission decays collected at pH 9 ( Figure S2 and S5, Supporting Information) gave DAS spectra ( Figure 6B) that demonstrated opposite effects induced by the addition of macromolecular host. In agreement with previous reports, 9,13,14 the complex at pH 9 excited at 320 nm has higher emission yield than that of free drug with excited-state lifetime of ~1.25 ns and no change in peak position at ~ 390 nm (Table 2) and calculated using the known equation: …”

Section: 19supporting

confidence: 91%

Sequestration Effect on the Open-Cyclic Switchable Property of Warfarin by Cyclodextrin: Ultrafast Dynamical Study

Al-Dubaili¹,

Saleh²

2017

Preprint

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ABSTRACT:The excited-state lifetimes of the anticoagulant drug warfarin (W) in water and in the absence and presence of methyl-β-cyclodextrins (Me-β-CD) were recorded using time-resolved fluorescence measurements. Selective excitation of the open and cyclic protonated isomers of W were acquired with laser emitting diodes (LED) producing 320 and 280 nm excitation pulses, respectively. Formation of the inclusion complex was checked by UV-visible absorption spectroscopy, and the values of binding constants (2.9 × 10 for protonated and deprotonated forms, respectively) were extracted from the spectrophotometric data. Both absorption and time-resolved fluorescence results established that the interior of the macromolecular host binds preferentially the open protonated form, red shifts the maximum of its absorption of light at ~305 nm, extends its excited-state lifetime, and decreases its emission quantum yield (ФF). Collectively, sequestration of the open guest molecules decreases markedly their radiative rate constants (kr), likely due to formation of hydrogen-bonded complexes in both the ground and excited states. Due to lack of interactions, no change was observed in the excited-state lifetime of the cyclic form in the presence of Me-β-CD. The host also increases the excited-state lifetime and ФF of the drug deprotonated form (W¯). These later findings could be attributed to the increased rigidity inside the cavity of Me-β-CD. The pKa values extracted from the variations of the UV-visible absorption spectra of W versus the pH of aqueous solution showed that the open isomer is more acidic in both ground and excited states. The positive shifts in pKa values induced by three derivatives of cyclodextrins: HE-β-CD, Ac-β-CD, and Me-β-CD supported the preferential binding of these hosts to open isomers over cyclic.

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Section: 19supporting

confidence: 91%

Sequestration Effect on the Open-Cyclic Switchable Property of Warfarin by Cyclodextrin: Ultrafast Dynamical Study

Al-Dubaili¹,

Saleh²

2017

Preprint

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“…A typical instrumental pulse using an IBH TBX-04 detector at a time calibration of 13 ps per channel and a scattering sample of LUDOX 1 was about 600 ps at full width half maximum. To remove the additional excitation pulse Ishiwata and Kamiya (1997), Vasquez et al (2009) from the NanoLed at around 430 nm, a cut-off filter (UG-11) was kept in front of the excitation source. Before every sample measurement, the instrument response function was measured using LUDOX 1 solution (excitation and emission wavelengths 295 and 334 nm respectively).…”

Section: Time-resolvedmentioning

confidence: 99%

“…The traditional difficulties associated with correlating warfarin concentration with biological activity are reflected in the results of studies examining its binding to proteins involve in the bioavailabilty and even the direct action of warfarin. Human serum albumin (HSA) (Ha et al, 2000;Il'ichev et al, 2002;Petersen et al, 2002) and cytochrome P2C9 (CYP2C9) (He et al, 1999) and even binding site models such as the cyclodextrins (Ishiwata and Kamiya, 1997) have been examined. In these cases, the binding sites demonstrate preferences for different isomers, Table 1.…”

Section: Introductionmentioning

confidence: 99%

Warfarin: an environment‐dependent switchable molecular probe

Nicholls

Karlsson

Rosengren

et al. 2010

J of Molecular Recognition

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The complex nature of the structure of the anticoagulant warfarin is reflected in the diversity of binding modes observed in warfarin-protein recognition systems. A series of theoretical, 1 H-NMR and steady state and time resolved fluorescence spectroscopic studies, have been used to establish correlations between the molecular environment provided by various solvent systems and the relative concentrations of the various members of warfarin's ensemble of isomers. A consequence of these observations is that the judicious choice of solvent system or molecular environment of warfarin allows for manipulation of the position of the equilibrium between isomeric structures such as the hemiacetal and open phenol-keto forms, the latter even possible in a deprotonated form, where in each case unique spectroscopic properties are exhibited by the respective structures. Collectively, warfarin's capacity to adapt its structure as a function of environment in conjunction with the fluorescence behaviours of the various isomers together provide an environment-dependent molecular switch with reporter properties, which allows for the simultaneous detection of warfarin in different states with lifetimes spanning the range < 0.10-5.5 ns. These characteristics are here used to examine warfarin binding domains in a series of materials (solvents, protein, inorganic matrix and synthetic polymer). Moreover, these studies demonstrate the potential for using warfarin, or other switchable analogues thereof, as a tool for studying molecular level characteristics, for example local dielectricity.

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“…They use a sequential injection analysis method with a 0.02 µg ml -1 detection limit requiring 20 s for one analysis. Although warfarin is itself strongly fluorescent, it was shown by Ishiwata et al that CDs were enhancers of the fluorescence, with β-CD performing best [140]. In the procedure set-up by Tang et al, its signal could be amplified about 3.5 times.…”

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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Cyclodextrin inclusion effects on fluorescence and fluorimetric properties of the pesticide warfarin

Cited by 26 publications

References 16 publications

Sequestration Effect on the Open-Cyclic Switchable Property of Warfarin by Cyclodextrin: Ultrafast Dynamical Study

Sequestration Effect on the Open-Cyclic Switchable Property of Warfarin by Cyclodextrin: Ultrafast Dynamical Study

Warfarin: an environment‐dependent switchable molecular probe

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

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