Are the Cytotoxic Properties of Conjugated Unsaturated Ketones Inactivated by Thiols?

The focus of this study was to examine whether the conversion of cytotoxic conjugated unsaturated ketones (or enones) into the corresponding thiol adducts leads to a reduction or abolition of cytotoxic potencies. A number of enones and related thiol adducts were evaluated against human HCT116 and HT29 colon cancer cells. Some 63% of the IC50 values are less than 10 μM and several compounds are more toxic than 5-FU. The thiol adducts are either more potent or are equipotent with the corresponding enones. A number of compounds are far more toxic to HCT116 and HT29 neoplasms than non-malignant CRL1790 cells leading to impressive Selectivity Index figures. An additional positive feature of these compounds is that they have favorable ADME properties.