Synthesis, spectroscopic characterization and biological activity of cis-[Ru(hesperidin)(1,10′-phenanthroline)2](PF6) complex

The new complex cis-[Ru(phen)2(hesperidin)](PF6), complex 1, was synthesized and characterized by analytical (ESI-MS+, EA (C, H, N)) and spectroscopic (FTIR, UV–vis, 1H and 13C NMR) techniques and cyclic voltammetry. Complex 1 is chemically stable in the solid state and in organic solvents such as ethanol, methanol, acetone, and acetonitrile, as shown by spectrophotometric analysis. 1 is also photochemically and chemically stable (pH effects) and more hydrosoluble (518.83 ± 0.91 g mL−1) than free hesperidin (5.92 g mL−1). In accordance with this, the lipophilicity value in aqueous-octanol solution for 1 was −1.28, indicating its high hydrophilic characteristic. Although complex 1 showed to be essentially noncytotoxic, IC50 > 1.0 mmol L−1 as evaluated in the human cervical cancer cells line HeLa, it exhibited a moderate capacity of inhibiting the catalytic activity of the acetylcholinaesterase enzyme, IC50 = 63.6 mol L−1. The Lineweaver–Burk plot and the respective secondary replot indicated that the AChE inhibition was noncompetitive and reversible.These findings shows that complexation of the hesperidin improves physicochemical characteristics and increases the perspectives for development and medical applications of new bioactive-metal complexes.

The moderate inhibitory effect on the activity of acetylcholinesterase and low cytotoxicity to HeLa cells, combined with the high water solubility of complex cis-[Ru(hesp)(phen)2]2+ in different types of medium (pH 3.09–9.05) offer the opportunity to explore many biological activities of the complex in the physiological medium.Figure optionsDownload as PowerPoint slideHighlights
► This is the first report on the binding of Ru(II) complexes with hesperidin.
► Complex formation increased the solubility and stability of the hesperidin.
► The complex is essentially noncytotoxic to the human cervical cancer cells line HeLa.
► The complex is noncompetitive inhibitors of AChE (E. electricus) enzyme.
► The hesperidin-metal increases the perspectives for development of new bioactive.