Quantitative assessment of the interactions between the organogermanium compound and saccharides using an NMR reporter molecule.

Poly-trans-[(2-carboxyethyl)germasesquioxane], Ge-132, is a water-soluble organogermanium compound reported to have physiological effects such as immunostimulatory and antiviral effects. The hydrolysate of Ge-132, 3-(trihydroxygermyl)propanoic acid (THGP), can interact with diols; therefore, it likely can interact with diol-containing sugars in sugar chains, glycoproteins, and glycolipids, which have important physiological functions. In this study, we quantitatively assessed the ability of THGP to interact with saccharides using nuclear magnetic resonance (NMR) spectroscopy and THGP derivatives. THGP was complexed by binding its trihydroxy group with saccharides in aqueous solutions via the cis-diol group rather than the trans-diol group. The spectra of THGP and monosaccharides indicated that THGP has a higher affinity for ketose than aldose. Moreover, the complexation ability between THGP and saccharides was influenced by the number of cis-diol groups on the saccharide structure. Thus, interactions of THGP with important biological sugars might be involved in the physiological functions of Ge-132.