Synthesis of N-substituted indole-2-carboxamides and investigation of their biochemical responses against free radicals

Abstract

The antioxidant role of novel N-substituted indole-2-carboxamides (I2CDs) was investigated for their inhibitory effects on superoxide anion (O₂⁻ ) and lipid peroxidation (LP). Among the synthesized I2CDs, 3, 4, 6, 8 and 9 significantly inhibited O₂^{· −} with an inhibition range at 70–98%. Examination of substituent effects on activity showed that both the ortho- and para-positions of the benzamide residue needs to be dichlorinated in order to get a maximum inhibitory effect on superoxide anion. In general, halogenated derivatives were found more active then the non-halogenated ones. However, none of the I2CDs had a significant inhibitory effects on the level of lipid peroxidation; only compounds 7 and 10 moderately decreased LP levels by over 50% at 10^{− 3} M concentrations.

Keywords::

• Indole-2-carboxamides
• reactive oxygen species
• superoxide dismutase
• lipid peroxidation
• inhibition
• synthesis

Acknowledgements

The authors thank Prof. Dr Hakan Göker for providing NMR and Mass spectral analysis and also special thanks to M.Sc Mehmet Alp for Elemental analysis.