Niobium(V) peroxo alpha-amino acid complexes: Synthesis, stability and kinetics of inhibition of acid phosphatase activity

作者：Gogoi Sandhya Rani; Saikia Gangutri; Ahmed Kabirun; Duarah Rituparna; Islam Nashreen S^*

来源：Polyhedron, 2017, 121: 142-154.

DOI：10.1016/j.poly.2016.09.057

• Peroxoniobium complex
• ACP inhibition
• Catalase resistance
• Heteroleptic peroxoniobate
• Biogenic ligand

The present work was undertaken with an objective to investigate some biologically relevant attributes of peroxoniobium (pNb) derivatives, using a set of heteroleptic pNb compounds containing biogenic species as co-ligands. New peroxoniobium complexes corresponding to the general formula, Na-2[Nb(O-2)(3)L] (L = alanine or valine) were synthesized and comprehensively characterized by elemental analysis, IR, Raman, C-13 NMR, H-1 NMR, AAS and UV-Vis spectral studies, as well as thermogravimetric analysis. The structures of the compounds have been studied by density functional theory (DFT) method and their stability in solution at physiological pH has been ascertained. These compounds, along with our previously reported arginine and nicotinate complexes, Na-2[Nb(O-2)(3)(arg)]center dot 2H(2)O and Na-2[Nb(O-2)(3)(nic)(H2O)]. H2O, respectively were screened for their activities with two different types of enzymes viz., catalase and acid phosphatase (ACP). Employing wheat thylakoid ACP as the model enzyme, it has been demonstrated for the first time that peroxoniobium derivatives serve as active inhibitors of phosphatase (IC50 values 2-9 mu M). Enzyme kinetics data revealed that compounds exert mixed type of inhibition on ACP activity (K-ii > K-i) Each of the tested pNb species exhibited significant resistance to degradation under the effect of catalase vis-a-vis the native substrate of the enzyme, H2O2.

• 出版日期2017-1-10