Structure and conformation of α-, β- and γ- cyclodextrin in solution :Theoretical approaches and experimental validation

Cyclodextrins (CDs) are cyclic oligosaccharides built up from α-Dglucopyranose units connected with a α-1, 4 glycosidic linkage, figure 1. One of the most remarkable applications of CDs is its use as drug carriers in controlled release systems. For example as drugcarriers, β-CD allows the solubilization, stabilization, and transport of hydrophobic drugs together with several pharmacological benefits such as the reduction of unwanted side effects. Between different methods to study of carbohydrate especially oligosaccharide conformation, theoretical calculation of NMR properties, in combination with NMR experimental data, can produce lots of information about the structure details of such molecules. In most of these approaches, estimation of internuclear distances between oligosaccharide proton pairs is obtained using 1D or 2D nuclear Overhausser enhancement (NOE) experiments, and structural information is derived from homo and hetero nuclear vicinal (3J) and geminal (2J) coupling constants [1]. Carbohydrate 13C chemical shifts have been employed as another valuable source of structural information that could be used instead of NOE and Jcoupling data. In particular, the anomeric carbon chemical shift is depended on the glycosidic bond; φ and ψ dihedral angles.