Antioxidant and antitumor activities of 4-arylcoumarins and 4-aryl-3,4-dihydrocoumarins

Abstract Five 4-arylcoumarins ( 1c – g ) and twelve 3,4-dihydro-4-arylcoumarins ( 2a – l ) were synthesized and tested for antioxidant activity, antitumor activity, toxicity and structure–activity relationships analysis. 4-Arylcoumarins and 3,4-dihydro-4-arylcoumarins that possess two hydroxyl groups in ortho position, such as 1d , 1f , 2a , 2f , 2g and 2h had stronger radical scavenging properties than that of vitamin C (Vit C) in ABTS + assay. Kinetic traces of scavenging ABTS + and DPPH radicals showed that all the reaction could reached endpoint in 1 min, which was similar with Vit C. 4-Arylcoumarins with 3′-hydroxyl-4′-methylphenyl structural show more efficient NO radical scavenging activity. Three compounds 2e , 1f and 2a , in particular had superior EC 50 for NO scavenging than did Vit C. MTT assay indicated that one compound in particular had a potential antitumor effect, inhibiting proliferation of BGC-823 cells and almost completely killing them at a concentration 62.5 mg/L. With same concentration 100 μg/mL, hemolytic analysis in rabbit red blood cells showed that only two compounds had hemolytic activity with a little more than 5% hemolysis. Injection and oral toxicity tests on Galleria mellonella larvae showed that none of the tested 4-arylcoumarins significantly affected their appetite, viability and mortality.