Influence of methoxy groups on the antiproliferative effects of [FeIII(salophene-OMe)Cl] complexes

We synthesized methoxy-substituted iron(III)-salophene complexes ([FeIII(OMe-salophene)Cl] with salophene = N,N′-bis(salicylidene)-1,2-phenylenediamine) and analyzed their biological activity in MCF-7 and MDA-MB-231 breast cancer as well as in HT-29 colon carcinoma cells. The results obtained in a time-dependent chemosensitivity test clearly demonstrated the correlation between the cytotoxicity of the complexes and the position of methoxy substituents in the salicylidene moieties: 3-OCH3 (4) < 5-OCH3 (8) < H (2) < 4-OCH3 (6) = 6-OCH3 (10). Compounds 6 and 10 caused cytocidal effects already at a concentration of 0.5 μM. Both lead compound 2 and complex 8 showed similar time response curves, however, with a 5-fold lower activity compared to 6 and 10, respectively. Referring to [FeIII(salophene)Cl] (2), methoxy substitution was accompanied with the loss of tumor cell selectivity. Moreover, the free ligands (1, 3, 5, 7, and 9) were inactive.

A series of methoxy-substituted iron(III)-salophene complexes (salophene = N,N′-bis(salicylidene)-1,2-phenylenediamine) were synthesized and evaluated for cytotoxicity against breast cancer (MCF-7, MDA-MB-231) as well as colon cancer (HT-29) cell lines.Figure optionsDownload as PowerPoint slide