Synthesis and antioxidant activity study of new mannich bases derived from vanillic acid

Abstract

We synthesized five new Mannich bases compounds from vanillic acid and evaluated for their antioxidant activities using a free-radical DPPH and FRAP methods. The compounds' structures were confirmed based on infrared, proton NMR, carbon NMR, and mass spectra. In this study, the compound 5-(pyrrolidin-1-ylmethyl)vanillic acid (2e) showed the best free-radical scavenger activity, while compound 2-[(diethylamino)methyl]vanillic acid (2c) showed the best as a ferric reductant. Mannich bases enhanced the free-radical scavenger activity but decreasing the ferric reduction potential of the parent compounds. The compounds were found to be moderate antioxidant agents.