Synthesis, characterization and antioxidant activity of water soluble MnIII complexes of sulphonato-substituted Schiff base ligands.
Two new Mn(III) complexes Na[Mn(5-SO(3)-salpnOH)(H(2)O)]5H(2)O (1) and Na[Mn(5-SO(3)-salpn)(MeOH)]4H(2)O (2) (5-SO(3)-salpnOH=1,3-bis(5-sulphonatosalicylidenamino)propan-2-ol, 5-SO(3)-salpn=1,3-bis(5-sulphonatosalicylidenamino)propane) have been prepared and characterized. Electrospray ionization-mass spectrometry, UV-visible and (1)H NMR spectroscopic studies showed that the two complexes exist in solution as monoanions [Mn(5-SO(3)-salpn(OH))(solvent)(2)](-), with the ligand bound to Mn(III) through the two phenolato-O and two imino-N atoms located in the equatorial plane. The E(1/2) of the Mn(III)/Mn(II) couple (-47.11 (1) and -77.80mV (2) vs. Ag/AgCl) allows these complexes to efficiently catalyze the dismutation of O(2)(-), with catalytic rate constants 2.4x10(6) (1) and 3.6x10(6) (2) M(-1)s(-1), and IC(50) values of 1.14 (1) and 0.77 (2) muM, obtained through the nitro blue tetrazolium photoreduction inhibition superoxide dismutase assay, in aqueous solution of pH 7.8. The two complexes are also able to disproportionate up to 250 equivalents of H(2)O(2) in aqueous solution of pH 8.0, with initial turnover rates of 178 (1) and 25.2 (2) mM H(2)O(2) min(-1)mM(-1)catalyst(-1). Their dual superoxide dismutase/catalase activity renders these compounds particularly attractive as catalytic antioxidants.
IQUIR (Instituto de Química Rosario) - CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina.
Diego
D
Moreno
Verónica
V
Daier
Claudia
C
Palopoli
Jean-Pierre
JP
Tuchagues
Sandra
S
Signorella
D000818:Animals; D000975:Antioxidants / Q000737:chemistry*; D002374:Catalase / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D055664:Electrochemical Techniques; D006801:Humans; D008024:Ligands; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D012545:Schiff Bases / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D017550:Spectroscopy, Fourier Transform Infrared; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism; D014867:Water / Q000737:chemistry*
D000975:Antioxidants; D008024:Ligands; D012545:Schiff Bases; D014867:Water; D008345:Manganese; D002374:Catalase; D013482:Superoxide Dismutase