Electrochemical evaluation of the antioxidant capacity of hydroxylated benzylideneamino imidazole derivatives

Abstract

Oxidative stress (OS) has been associated with a wide range of diseases such as atherosclerosis, cancer, and neurodegenerative disorders [1-3]. Oxidative stress occurs when intracellular oxidizing species, such as reactive oxygen species (ROS), increase abnormally and is often accompanied by a simultaneous loss of antioxidant capacity [4]. Therefore, the development and synthesis of new compounds (drugs) that are able to scavenge ROS or prevent their formation are important for the prevention and therapy of these diseases. Numerous methods can then be applied to evaluate the compounds antioxidant capacity and, both chemical and electrochemical methods have been used with this purpose [5,6]. A few studies demonstrated that imidazole-containing compounds are active as antioxidant agents [7]. On the other hand the antioxidant activity of several phenolic compounds is known for a long time. As part of a research program aiming to obtain new antioxidants we synthesized new compounds combining an imidazole ring with phenolic units. The novel hydroxylated benzylideneamino imidazole derivatives combined an imidazole ring with electron withdrawing or electron donating substituents in N1, and phenolic subunits having one, two or three hydroxyl groups in different positions of the ring. In this work, the antioxidant capacity of the new phenol-imidazole conjugates and of the starting imidazoles and aldehydes, was assessed by voltammetric methods. Antioxidant capacity data obtained from cyclic voltammetry measurements were correlated with DPPH radical assay data. It was found that the antioxidant capacity of hydroxylated benzylideneamino imidazole derivatives depends mainly on the phenolic subunit (number and position of the hydroxyl groups) and the extent of conjugation with the imidazole ring.