Thermodynamics of κ-Carrageenan–Amphiphilic Drug Interaction as Influenced by Specific Counterions and Temperature: A Microcalorimetric and Viscometric Study

Singh, Satish Kumar; Caram-Lelham, Ninus

doi:10.1006/jcis.1998.5502

Cited by 33 publications

(15 citation statements)

References 32 publications

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“…Approximately 98% of the binding results from entropy, with only 2% contribution from enthalpy [69]. The second binding site contains a binding affinity of (6.1 ± 1.4) × 10 5 M −1 , a binding enthalpy of −0.34 ± 0.03 kcal/mol, and a binding entropy of 7.2 kcal/mol K. Our thermodynamic studies can not offer a more detailed explanation of the nature of the second binding site, as it differs from the first site.…”

Section: Resultsmentioning

confidence: 99%

“…For paromomycin, the enthalpic contribution, smaller than for neomycin, is approximately 75% in cacodylate buffer and 44% in MOPS buffer. Given the fact that the intrinsic binding is entropy-driven at pH 5.5, the enthalpically favorable binding at pH 6.8 suggests that a non-negligible drug protonation effect is clearly involved during binding [69,73–75]. …”

Section: Resultsmentioning

confidence: 99%

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Calorimetric and spectroscopic studies of aminoglycoside binding to AT-rich DNA triple helices

Kumar

Došen‐Mićović

et al. 2010

Biochimie

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Calorimetric and fluorescence techniques were used to characterize the binding of aminoglycosides-neomycin, paromomycin, and ribostamycin, with 5′-dA12-x-dT12-x-dT12-3′ intramolecular DNA triplex (x = hexaethylene glycol) and poly(dA).2poly(dT) triplex. Our results demonstrate the following features: (1) UV thermal analysis reveals that the Tm for triplex decreases with increasing pH value in the presence of neomycin, while the Tm for the duplex remains unchanged. (2) The binding affinity of neomycin decreases with increased pH, although there is an increase in observed binding enthalpy. (3) ITC studies conducted in two buffers (sodium cacodylate and MOPS) yield the number of protonated drug amino groups (Δn) as 0.29 and 0.40 for neomycin and paromomycin interaction with 5′-dA12-x-dT12-x-dT12-3′, respectively. (4) The specific heat capacity change (ΔCp) determined by ITC studies is negative, with more negative values at lower salt concentrations. From 100 mM to 250 mM KCl, the ΔCp ranges from −402 to −60 cal/(mol K) for neomycin. At pH 5.5, a more positive ΔCp is observed, with a value of −98 cal/(mol K) at 100 mM KCl. ΔCp is not significantly affected by ionic strength. (5) Salt dependence studies reveal that there are at least three amino groups of neomycin participating in the electrostatic interactions with the triplex. (6) FID studies using thiazole orange were used to derive the AC50 (aminoglycoside concentration needed to displace 50% of the dye from the triplex) values. Neomycin shows a seven fold higher affinity than paromomycin and eleven fold higher affinity than ribostamycin at pH 6.8. (7) Modeling studies, consistent with UV and ITC results, show the importance of an additional positive charge in triplex recognition by neomycin. The modeling and thermodynamic studies indicate that neomycin binding to the DNA triplex depends upon significant contributions from charge as well as shape complementarity of the drug to the DNA triplex Watson–Hoogsteen groove.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Calorimetric and spectroscopic studies of aminoglycoside binding to AT-rich DNA triple helices

Kumar

Došen‐Mićović

et al. 2010

Biochimie

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show abstract

“…However, the free energies for the micellization of the surface-active drug molecules in solution are of the same magnitude as the free energy for absorption of drug molecules to the carrier matrix. Therefore, the hydrophobic moieties of the drug interact and tend to stabilize a cluster-like structure at the matrix of the carriers, which means that cooperative binding phenomenon has the same energetics as the micellization [8]. As far as the epileptic drugs are concerned, the surface activity of the drugs can predict their ability to cross the blood-brain barrier and can be quantified by cmc and surface area requirement of the drug at the air/water interface.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics studies on tyrosine-hydantoin drug–cetyltrimethylammonium bromide mixed micellar system

Tiwary

Mandal

Alam

et al. 2011

Colloids and Surfaces B: Biointerfaces

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“…They are GRAS and are also of pharmaceutical grade. The polyanionic nature of CARRs was shown to have a possible crucial influence on drug release behaviour as well (Singh and Lelham, 1998).…”

Section: Introductionmentioning

confidence: 99%

Matrix tablets based on carrageenans with dual controlled release of doxazosin mesylate

Pavli

Vrečer

Baumgartner

2010

International Journal of Pharmaceutics

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Thermodynamics of κ-Carrageenan–Amphiphilic Drug Interaction as Influenced by Specific Counterions and Temperature: A Microcalorimetric and Viscometric Study

Cited by 33 publications

References 32 publications

Calorimetric and spectroscopic studies of aminoglycoside binding to AT-rich DNA triple helices

Calorimetric and spectroscopic studies of aminoglycoside binding to AT-rich DNA triple helices

Thermodynamics studies on tyrosine-hydantoin drug–cetyltrimethylammonium bromide mixed micellar system

Matrix tablets based on carrageenans with dual controlled release of doxazosin mesylate

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