Recebido em 28/3/05; aceito em 14/10/05; publicado na web em 12/4/06 A detailed NMR ( 1 H , COSY, ROESY) spectroscopic study of complexation of enalapril maleate with β-cyclodextrin was carried out. The 1 H NMR spectrum of enalapril maleate confirmed the existence of cis-trans equilibrium in solution, possibly due to hindered rotation along the amide bond. The cis-trans ratio remained almost the same in the presence of β-cyclodextrin but in one case it was found significantly different which suggests a catalytic role of β-cyclodextrin in the isomerization. 1 H NMR titration studies confirmed the formation of an enalapril-β-cyclodextrin inclusion complex as evidenced by chemical shift variations in the proton resonances of both the host and the guest. The stoichiometry of the complex was determined to be 2:1 (guest: host). The mode of penetration of the guest into the β-cyclodextrin cavity as well as the structure of the complex were established using ROESY spectroscopy.
The complexation of triprolidine hydrochloride (TRP) and β-cyclodextrin (β-CD) in deuterium oxide was investigated by 400 MHz 1 H NMR spectroscopy. The 800 MHz 2D ROESY data revealed that two 1∶1 and one 2∶1 β-CD-TRP inclusion complexes were formed. Both aromatic moieties (p-tolyl and pyridyl ring) has entered into the β-CD cavity, confirming the existence of two different equilibria for 1∶1 inclusion complexes in which p-tolyl ring of the guest is more tightly held by the host cavity. The ROE intermolecular interactions provided the plausible structures of these 1∶1 and 2∶1 stoichiometric inclusion complexes of β-CD-triprolidine hydrochloride in solution.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.