Synthesis and Antioxidant Activity of Indole Derivatives Containing 4-Substituted Piperazine Moieties

Background: Oxidative stress caused by reactive oxygen species (ROS) plays a significant role in many human disorder such as cancer, rheumatoid arthritis, atherosclerosis, stroke, neurodegeneration, and diabetes as well as the process of aging. Compounds interfere with the action of ROS might be useful in prevention and treatment of these pathologies. Indole nucleus seems to protect the nervous system against oxidative stress. Methods: Herein, several indole compounds containing 4-substituted piperazine moieties were synthesized. Compounds 1, and 4-15 were obtained by amidification reaction using 1,1’-carbonyldiimidazole (CDI) and compounds 2 and 3 were obtained by the reaction of amine and substituted chloropyridine ring using potassium carbonate. Antioxidant activities of compounds were determined by in vitro lipid peroxidation levels on rat liver, superoxide formation and 2,2-diphenyl-1-picrylhydrazyl (DPPH) stable radical scavenging activities in comparison with vitamine E (α-tocopherol). Results: The results indicated that compounds 6 (75%), 7 (66%), 8 (75%), 11 (88%), and 12 (69%) showed strong inhibiory effects on superoxide radical formation compare to vitamine E (62%). Compound 11 can be considered as the most active one among them. Compound 10 (38%) showed slight activity in lipid peroxidation inhibition assay. Compounds are not good inhibitor of DPPH except compound 10, which has also slight inhibition (20%).