In Vitro Antioxidant and Insulin Mimetic Activities of Heteroleptic Oxovanadium(IV) Complexes with Thiosemicarbazones and Naproxen

Six heteroleptic oxovanadium(IV) complexes with general formula [VOL1-6(nap)], where, L1-3=2-(1-(4-substitutedphenyl)ethylidene)hydrazinecarbothioamide, L4-6=2-(1-(4-substitutedphenyl)ethylidene)-N-methylhydrazinecarbothioamide and nap=naproxen, have been synthesized and characterized. FTIR spectra exhibit a strong band between 965 and 991 cm(-1), characteristic of upsilon(V=O) stretching vibration. UV-Vis and theoretical studies suggested distorted square-pyramidal geometry and oxidation state of vanadium(IV) with d(1)configuration was confirmed by EPR spectra. Cyclic voltammograms exhibit metal based irreversible redox peaks corresponding to one electron oxidation (+0.83 to +0.70 V) and reduction (-0.69 to -0.53 V) processes. In vitro antioxidant studies revealed that complexes containing electron donating substituent (-CH3) showed higher activity. In vitro antidiabetic activity of complexes with enzymes like alpha-amylase, alpha-glucosidase and glucose-6-phosphatase made them better inhibitors of insulin, which is further supported by in silico studies, and complex6shows better in vitro insulin mimic activity against insulin responsive 3T3-L1 adipocyte cells compared to insulin and metformin.