STRUCTURE - CYTOTOXICITY RELATIONSHIPS OF A SERIES OF NATURAL AND SEMISYNTHETIC SIMPLE COUMARINS AS ASSESSED IN 2 HUMAN TUMOR-CELL LINES

The cytotoxicity of 22 natural and semi-synthetic simple coumarins was evaluated in GLC(4), a human small cell lung carcinoma cell line, and in COLO 320, a human colorectal cancer cell line, using the microcult ure tetrazolium (MTT) assay. With IC50 values > 100 mu M, following a continuous (96h) incubation, most coumarins exhibited only low cytotox icity. Several compounds, however, displayed significant potencies. As far as the structure - cytotoxicity relationship is concerned, it is conspicuous that all the potentially active natural compounds possess at least two phenolic groups in either the 6,7- or 6,8-positions. In a ddition, the 5-formyl-6-hydroxy substituted semi-synthetic analogue wa s found to be potent, reflecting the importance of at least two polar functions for high cytotoxicity.