Nuclear magnetic resonance studies of the interactions between the organic germanium compound Ge-132 and saccharides

Poly-trans-[(2-carboxyethyl)germasesquioxane], Ge-132, is a water-soluble organic germanium compound with many reported physiological functions. The hydrolysate of Ge-132, 3-(trihydroxygermyl)propanoic acid, can interact with diol compounds; therefore, it can possibly interact with diol-containing sugar compounds, which have important physiological functions in sugar chains, glycoproteins, and glucolipids. In this study, we examined the interaction between sodium 3-(trihydroxygermyl)propanoate and monosaccharides using nuclear magnetic resonance. When 1,4-anhydroerythritol was mixed with sodium 3-(trihydroxygermyl)propanoate, a pattern of signals different from that obtained for each solute alone was observed. Some signals were broader, and novel signals with different chemical shifts appeared to originate from complex formation. Spectral observations for sodium 3-(trihydroxygermyl)propanoate and the sugar isomers of glucose and fructose indicated that sodium 3-(trihydroxygermyl)propanoate has a higher affinity for fructose (a ketose) than glucose (an aldose). Moreover, the β-furanosyl conformation of fructose was the structure that interacted most with sodium 3-(trihydroxygermyl)propanoate. These results demonstrate the ability of aqueous Ge-132 to form complexes with the cis-diol structures of saccharides. Thus, interactions among 3-(trihydroxygermyl)propanoic acid and the important biological sugar compounds might be implicated in the physiological function of Ge-132.