The corresponding luminescent complexes derived from coumarines functionalized by a propynyloxy group at the 4- or 7-position or two propynyloxy groups in the 6,7-positions (compounds 134 and 135a–b) have triggered strong cytotoxicity against HT-29 colon carcinoma (IC50 values of 1.84, 2.13, and 3.14 μM respectively), which was attributed to the cation tetraphenylphosphonium and their high inhibition of the enzyme thioredoxin reductase [122]. This evidence concerns the gene PRDX5 and colon carcinoma.