MALTOL COMPLEXES OF VANADIUM(IV) AND VANADIUM(V) REGULATE IN-VITRO ALKALINE-PHOSPHATASE ACTIVITY AND OSTEOBLAST-LIKE CELL-GROWTH

Vanadium compounds have been found to possess insulin- and growth fact or-mimetic effects, In consequence, these derivatives are potentially useful as effective oral therapeutic agents in diabetic patients. Howe ver, their use has been limited by various toxic side-effects and by t he low solubility of different derivatives. Recently, vanadium complex es with maltol, a sugar used as a common food additive, have been synt hesised and investigated in animals, showing possible insulin-mimetic effects with low toxic side-effects. In the present study we have inve stigated the effect of bis(maltolato)oxovanadium (IV) (BMOV) and bis(m altolato)dioxovanadium (V) (BMV) on bone cells in culture as well as t heir direct effect on alkaline phosphatase in vitro. A comparison was also made with the action of vanadate and vanadyl cation. Vanadium com pounds regulated cell proliferation in a biphasic manner with similar potencies. Osteoblast differentiation, assessed by alkaline phosphatas e activity, was found to be dose-dependent. with the inhibitory effect being stronger for vanadate and BMOV than for vanadyl and BMV. All va nadium compounds directly inhibited bovine intestinal ALP with a simil ar potency. Thus, maltol vanadium derivatives behave in a similar way to vanadate and vanadyl in osteoblast-like UMR 106 cells in culture.