Amide and ester derivatives of chlorido[4-carboxy-1,2-disalicylideneaminobenzene]iron(iii) as necroptosis and ferroptosis inducers.

In continuation of the structure-activity study about 4-substituted chlorido[N,N'-disalicylidene-1,2-phenylenediamine]iron(iii) complexes as necroptosis and ferroptosis inducers, we introduced a 4-COOH group at the 1,2-phenylenediamine moiety of the lead ([Fe(iii)salopheneCl]) and derived the resulting complex 15 to the respective ethyl, propyl, or butyl amides (16-18) and esters (19-21). The compounds 16-21 exerted concentration-dependent antiproliferative and antimetabolic effects against HL-60 cells. The esters were more active than the analogous amides. Elongation of the alkyl chain enhanced the activity of the amides, while that of the esters decreased. The complexes 16-21 induced necroptosis and/or ferroptosis but not apoptosis. Studies on protein binding and uptake into HL-60 cells indicated that the complexes mainly accumulated by passive transport. The high binding tendency of all complexes to apo-Transferrin, however, points to participation of a carrier-mediated transport into the cells, too.