In the present investigation, we report on the possible underlying mechanism for the cytotoxicity of compounds: 3-(4-(2-(dimethylamino)ethoxy)-phenyl)-7-methoxy-4-phenyl coumarin 5, 3-(4-(2-(pyrrolidin-1-yl)ethoxy)phenyl)-7-methoxy-4-phenylcoumarin 6, and 3-(4-(2-(diethylamino) ethoxy)phenyl)-7-methoxy-4-methylcoumarin 7 in the human lung (A549) cancer cell line, using Ray Biotech's Human Apoptosis Arrays and apoptotic protein antibodies. Apoptosis array results showed differential apoptotic proteins expression in the extracts of cells treated with compounds 5-7. Western blotting demonstrated that compound 5 induced apoptosis and caused cell death in the A549 cell line via an increase (up-regulation) in Bax protein expression (pro-apoptotic pathway) and a slight decrease (down-regulation) in Bcl-2 protein expression (anti-apoptotic pathway) after 6 h of treatment. These observations may provide valuable information on the mechanism by which these coumarin-based benzopyranone derivatives induce cytotoxicity in the human lung (A549) cancer cell line.