Synthesis of novel amino and acetyl amino-4-methylcoumarins and evaluation of their antioxidant activity

The six novel 4-methylcoumarins bearing different functionalities such as amino, hydroxy, N-acetyl, acetoxy and nitro have been synthesized and confirmed on the basis of their spectral data (H-1-, C-13-NMR, UV, IR and El mass). They were examined for the first time for their effect on NADPH dependent liver microsomal lipid peroxidation in vitro, and the results were compared with other model 4-methylcoumarin derivatives to establish the structure-activity relationship. Our studies demonstrated that amino group is an effective substitute for the hydroxyl group for antioxidant property and produced a dramatic inhibition of lipid peroxidation. Ortho dihydroxy and ortho hydroxy-amino coumarins were found to possess highest antioxidant and radical scavenging activities. (c) 2005 Elsevier SAS. All rights reserved.