Oxidative stress protection by manganese complexes of tail-tied aza-scorpiand ligands

The Mn2+ coordination chemistry of double scorpiand ligands in which two polyazacyclophane macrocycles have been connected by pyridine, phenanthroline and bipyridine spacers has been studied by potentiometry, paramagnetic NMR and electrochemistry. All ligands show high stability with Mn2+ and the complexes were formed in a wide pH range. DFT calculations support the structures and coordination geometries derived from the study. A remarkable antioxidant activity was evidenced for these systems by the McCord-Fridovich assay and in Escherichia coli sodAsodB deficient bacterial cells. The three systems were tested as anti-inflammatory drugs in human macrophages measuring the accumulation of cytokines upon lipopolysaccharide (LPS) pro inflammatory effect. All complexes showed anti-inflammatory effect, being [Mn(2)L1](4+) the most efficient one. (C) 2016 Elsevier Inc. All rights reserved.