Mechanisms of Deceleration by Methylated Cyclodextrins in the Dehydration of Prostaglandin E_2 and the Isomerization of Prostaglandin A_2 in Aqueous Solution(Pharmaceutical)

概要

論文の詳細を見る
The effects of two kinds of methylated cyclodextrins, heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CyD) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TM-β-CyD), on the dehydration rate of prostaglandin E_2 (PGE_2) and the isomerization rate of prostaglandin A_2 (PGA_2) in aqueous solution were kinetically investigated in comparison with the effects of natural cyclodextrins (CyDs). The dehydration rate of PGE_2 in the acidic region was decelerated in the order of DM-β-CyD>β-CyD≧TM-β-CyD. On the other hand, the dehydration rate of PGE_2 in the neutral and alkaline regions was inhibited by both DM-β-CyD and TM-β-CyD, while β-CyD showed an accelerating effect. The base-catalyzed isomerization of PGA_2 was also inhibited by the complexation with DM-β-CyD, while β-CyD accelerated it. The mechanisms of deceleration by the methylated CyDs are discussed on the basis of the pH-profile, solvent effect, deuterium solvent kinetic isotope effect, and thermodynamic activation parameters.
1986-12-25