NMR Evidence for Self-Association of Theophylline in Aqueous Solution

Thakkar, Arvind L.; Tensmeyer, Lowell G.; Wilham, William L.

doi:10.1002/jps.2600600841

Cited by 30 publications

(17 citation statements)

References 7 publications

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“…For example, Coffman and Kildsig 8 suggested that hydrotropic agents changed the nature of the solvent by altering the solvent's ability to participate in structure formation via intermolecular hydrogen bonding (HB). Other researchers, noticing that hydrotropic agents often tend to self-aggregate in aqueous solutions, [23][24][25][26] speculated that molecular aggregation might account for their hydrotropic effects. 17,27,28 These proposals, nevertheless, have run into their own counterarguments.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Hydrotropic Solubilization and Self-Aggregation of Nicotinamide

Cui¹,

Xing

Ran³

2010

Journal of Pharmaceutical Sciences

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Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Hydrotropic Solubilization and Self-Aggregation of Nicotinamide

Cui¹,

Xing

Ran³

2010

Journal of Pharmaceutical Sciences

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“…It is well established that upfield shifts, as observed here, indicate plane to plane or vertical stacking. [17] The magnitudes of the differences in chemical shift varied for the RA signals, with larger chemical shift displacements for the aromatic ring A protons (2,6 ArH) and olefinic protons (7,8 CH = CH) compared to the displacements of the aromatic ring B protons (5′,6′ArH) and saturated protons (7′,8′ CH 2 -CHCOOH). The larger chemical shift changes correspond to the most favorable binding sites, which are therefore the least subject to conformational averaging of the aggregate with the monomer.…”

Section: Resultsmentioning

confidence: 99%

The structure‐dependent self‐association of five phenolic acids in aqueous solution

Xiao

Zhang

et al. 2014

Magnetic Reson in Chemistry

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Weak self-interaction plays an important role in interpreting the biomechanisms and modes of drug action. The structure-dependent self-association of five phenolic acids with various bioactivities, including danshensu (DSS), caffeic acid (CA), rosmarinic acid (RA), lithospermic acid (LA), and salvianolic acid B (SA), was investigated by (1)H NMR. These phenolic acids have similar condensed structures, with a CA moiety and varying numbers of DSS moieties. The strengths of the self-association constants are in the order DSS < CA < RA < LA < SA, which corresponds to the increasing molecular size of these phenolic acids and roughly corresponds to the increasing number of DSS moieties. The binding site for the self-aggregation of these phenolic acids has been identified to be on the CA moiety, rather than on the DSS moiety, as a result of CA's stronger aromatic π-π interactions, which cause larger chemical shift variations. The thermodynamic parameters for the self-association of these phenolic acids show that the self-association is spontaneous and enthalpically favorable at room temperature in all cases. It was inferred that π-π interactions and intermolecular hydrogen bonding stabilize the stacking structures of the phenolic acids. Knowledge of self-association processes will enable us to quantitatively assess the possible effects of self-aggregation on the interaction between drug and protein.

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“…In all probability, theophylline does dimerize or associate in some fashion in aqueous solution, as suggested by Thakkar et al (1). A total lack of associative tendency is quite unlikely, since it was shown conclusively that closely related derivatives of theophylline readily form not only dimers but also more highly associated species (2).…”

Section: Sirmentioning

confidence: 90%

“…The separation and quantitative determination of standard mixtures of the iodoamino acids by GLC were reported by many authors (1)(2)(3)(4)(5)(6)(7)(8). The separation and quantitative determination of standard mixtures of the iodoamino acids by GLC were reported by many authors (1)(2)(3)(4)(5)(6)(7)(8).…”

Section: Sirmentioning

confidence: 98%