Antioxidant properties of water-soluble phthalocyanines containing quinoline 5-sulfonic acid groups

Abstract

In the present study, the antioxidant properties of peripherally and nonperipherally water-soluble tetra (quinoline 5-sulfonic acid) substituted metal-free (1,2), Zn(II) (3, 4), Co(II) (5, 6), and Mn(III)Cl (7, 8) phthalocyanine (Pc) derivatives were reported. In order to determine the antioxidant properties of the Pc compounds, three different commonly known antioxidant methods were used: DPPH ($\alpha $,$\alpha $-diphenyl-$\beta $-picrylhydrazyl) radical scavenging, ferrous ion chelating, and reducing power assays. Compound \textbf{6} showed the best DPPH activity among the other tested compounds except for the standards. The ferrous ion chelating IC$_{50\, }$value of compound 7 was nearly as good as that of the EDTA standard. The reducing power activity results indicated that the tested Pc compounds were as sensitive as standard reducing agents such as butylated hydroxytoluene and ascorbic acid. Overall, all tested compounds showed good antioxidant properties and it may be suggested that they could be used as new positive controls for reducing power assays in the future works.