A New Type of Orally Active Insulin-Mimetic Vanadyl Complex: Bis(1-oxy-2-pyridinethiolato)oxovanadium(IV) with VO(S2O2) Coordination Mode

A new purple vanadyl complex, bis(1-oxy-2-pyridinethiolato)oxovanadium(IV), VO(OPT), with VO(S2O2) coordination mode, was prepared by mixing 2-mercaptopyridine-N-oxide or 1-hydroxy-2-pyridinethione and VOSO4, and characterized by UV, IR and EPR spectra, magnetic susceptibility and partition coefficient. Based on the higher in vitro insulin-mimetic activity of VO(OPT) (IC50 = 0.19 mM) than that of VOSO4 (IC50 = 0.9 mM), the complex was found to be a potent agent for treating insulin-dependent diabetes mellitus in rats when given by daily intravenous injection or oral administration.