Yeast mannan-vanadium (IV) complexes and their effect on peritoneal macrophages

In order to evaluate the formation of complexes between the vanadyl ion (IV) and bakerʹs yeast mannan (MPOLY), methyl α-d-mannopyranoside (MM) was used as a model. The interaction was examined using potentiometric titration and infrared spectroscopy. The potentiometric studies provided the binding constant for the complex and the resulting complexed species were a function of pH. FTIR spectra contained a sharp and strong band at 1381 and 1382 cm−1 for MM–VO and MPOLY–VO, respectively, absent in non-complexed spectra. In contrast to free carbohydrates, MPOLY–VO and MM–VO were highly toxic to macrophages. The mannan and its complexes with vanadyl ion lowered superoxide anion production in macrophages triggered with PMA. MPOLY enhanced nitric oxide production (55%), this effect not being observed for MPOLY–VO as well as MM and MM–VO.