633AGAIN TO THE SPECIFICITY OF COUMARINSThe aim of the present investigation was to evaluate the effect of coumarin, 6,7-dihydroxycoumarin, 5,7-dihydroxy-4- methylcoumarin and 7,8-dihydroxy-4-methylcoumarin on the ROS-emission by different tumor cells (human epithelial colorectal carcinoma HT-29, breast cancer epithelial-like morphology MDA-MB-231, epithelial cervix adenocarcinoma HeLa and hepatocellular liver carcinoma HepG2.). Such effects were observed by means of the antiproliferative MTS-test. The data varied for the different cell lines and depended on the particular coumarin derivative. The antioxidant properties of coumarins were examined by HORAC (HO•-radical) and ORAC (RO2•-radical) dianaw33@hotmail.comResearch672015 Tumor cells,ROS,HORAC,ORACIvan Goshev,Diana Wesselinova,Milan Ciz,Antonin Lojek,Violeta Petrova Institute of Organic Chemistry with Centre of Phytochemistry – Bulgarian Academy of Sci, Sofia, Bulgaria,Institute of Experimental Morphology, Pathology and Anthropology with Museum - Bulgarian Academy of Sci., Sofia, Bulgaria, Institute of Biophysics, Czech Academy of Sci., Brno, Czech Republic, Institute of Biophysics, Czech Academy of Sci., Brno, Czech Republic,Institute of Experimental Morphology, Pathology and Anthropology with Museum - Bulgarian Academy of Sci., Sofia, Bulgaria