Interactions of beta- and hydroxypropyl-beta-cyclodextrin with some purine alkaloids: thermodynamic study.
The effect of native and hydroxypropylated beta-cyclodextrin on the solubility and activity of some purine alkaloids was examined. For this purpose, the solubility of purine alkaloids in pure water and in aqueous solutions of mentioned beta-cyclodextrins was determined at 298.15 K. Stability constants of inclusion complexes and their stoichiometry were obtained from solubility diagrams. Enthalpic characteristics of interactions occurring between beta-cyclodextrins and purine alkaloids in aqueous solution were calculated from the direct calorimetric measurements. It was found, that beta-cyclodextrin forms with purine alkaloids weak complexes which are stabilized only by the entropy term. Due to very low complexing affinity of both beta-cyclodextrins to studied purine alkaloids their solubilizing effect is insignificant. The influence of structure of purine alkaloids and beta-cyclodextrin on the thermodynamic parameters of interaction was discussed.
Terekhova
Irina V
IV
Institute of Solution Chemistry of Russian Academy of Sciences, 1 Akademicheskaya Str., Ivanovo, Russian Federation. ivt@isc-ras.ru
D000073738:2-Hydroxypropyl-beta-cyclodextrin; D000470:Alkaloids / Q000737:chemistry*; D002151:Calorimetry; D002626:Chemistry, Pharmaceutical; D015394:Molecular Structure; D011687:Purines / Q000737:chemistry*; D012995:Solubility; D013329:Structure-Activity Relationship; D013678:Technology, Pharmaceutical / Q000379:methods*; D013696:Temperature; D013805:Theobromine / Q000737:chemistry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry; D019820:Xanthine / Q000737:chemistry; D047392:beta-Cyclodextrins / Q000737:chemistry*
D000470:Alkaloids; D011687:Purines; D047392:beta-Cyclodextrins; D014867:Water; D019820:Xanthine; D000073738:2-Hydroxypropyl-beta-cyclodextrin; D013805:Theobromine