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Calorimetric and NMR Studies of Inclusion Complexes of b-Cyclodextrin with Novel Amphiphilic Mannosides

Cyclodextrines (CDs) have been extensively studied due to their ability to host wide variety of hydrophobic compounds in water thus increasing their solubility in this solvent, and hence bioavailability.[1] The focus of our studies so far has been the synthesis of adamantyl glycosides and the evaluation of thermodynamic parameters of their complexation with b-CD in water.[2] Our present investigations have been directed to the complexation of other amphiphilic glycosides, namely, n-butyl, t-butyl, n-hexyl, cyclohexyl, n-octyl and cyclooctyl 2-(a- D-mannopyranosyloxy)acetates with b-CD in water and in organic solvents. Therefore, we present the synthesis of novel amphiphilic mannosylated esters of acetic acid possessing various alkyl parts (linear, branched or cyclic, Fig. 1). The esters were prepared by the reaction of acetylated or benzylated mannopyranose and corresponding esters of bromoacetic acid. Their complexation with b-CD was studied by means of titration calorimetry and NMR spectroscopy (1H, HSQC, COSY and ROESY techniques). The thermodynamic parameters of complexation (reaction enthalpies, standard reaction entropies, binding constants) were determined. Obtained results provide a deeper insight in correlations between guest structure and its complexation thermodynamics in investigated solvents.

amphiphilic mannosides ; beta-cyclodextrin ; titration calorimetry ; NMR spectroscopy

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