Vanadium(IV) and vanadium(V) complexes of dipicolinic acid and derivatives. Synthesis, X-ray structure, solution state properties: And effects in rats with STZ-induced diabetes

Preparation and characterization of new vanadium compounds with insulin mimetic properties is important for investigations into the mechanism of action of these complexes. In this work, we report the synthesis of three new compounds related to the (dipicolinato)dioxovanadium(V) complex: (4-hydroxy-2,6-pyridinedicarboxylato)dioxovanadium(V), (diaqua)(4-hydroxy-2,6- pyridinedicarboxylato)oxovanadium(IV) and (4-amino-2,6-pyridinedicarboxylato) dioxovanadium(V), and present the first preliminary kinetic study of a vanadium dipicolinate system. One of these complexes, (4-hydroxy-2,6- pyridinedicarboxylato)oxovanadium(V), is investigated in greater detail with regard to chemistry, structure, kinetics and insulin-like properties in rats with streptozotocin-induced diabetes. Oral administration of [VO ₂(dipic-OH)]^- was found to be effective in lowering both the hyperglycemia and hyperlipidemia of diabetes. This is the first report of the effective lowering of diabetic hyperlipidemia by a vanadium(V) coordination complex.