Iron(III) complexes using NNS reduced Schiff bases and NNOS coordinating tetradentate ligands: Synthesis, structure and catecholase activity

New ternary Fe(III)-8-hydroxyquinoline-reduced Schiff base complexes as selective anticancer drug candidates

Due to the growing prevalence of cancer diseases, new therapeutic options are urgently needed, and drugs based on metal ions other than platinum are alternatives with exciting possibilities. We report the synthesis, characterization and biological effect of mixed-ligand Fe(III)-aminophenolate complexes derived from salicylaldehyde and L-tryptophan with quinoline derivatives as co-ligands, namely 8-hydroxyquinoline (8HQ), [Fe(L)(8HQ)(H₂O)] (1) and its 5-cloro derivative (Cl8HQ), [Fe(L)(Cl8HQ)(H₂O)] (2). The complex bearing the aminophenolate and lacking the quinoline co-ligand, [Fe(L)(Cl)(H₂O)₂] (3), was prepared for comparison. The analytical and spectroscopic characterization revealed that 1 and 2 are octahedral Fe(III) complexes with the aminophenolate acting as a dianionic tridentate ligand and 8HQ co-ligands as bidentate chelates. Spectroscopic techniques and molecular docking studies were used to evaluate the ability of these complexes to bind bovine serum albumin (BSA) and calf thymus DNA. Complex 2 [Fe(L)(Cl8HQ)(H₂O)] was the one showing higher affinity for both biomolecules. Cell viability was assessed in breast, colorectal and bone human cancer cell lines. 1 and 2 were found to be more active than cisplatin in all cell lines tested. A non-tumoral fibroblast line (L929, mouse non-tumoral fibroblasts) was used to evaluate selectivity. The results evidence that 2 shows much higher selectivity than 1 in all cell lines tested, but particularly in bone cancer cells in which selectivity index (SI) values are 8.0 and 18.8 for 1 and 2, respectively.

Synthesis of imine and reduced imine compounds containing aromatic sulfonamide: use as catalyst for in situ generation of ruthenium catalysts in transfer hydrogenation of acetophenone derivatives

Three imine and three reduced imine ligands containing aromatic sulfonamide (2-7) were isolated by a simple method and characterized by FT-IR, NMR, and elemental analysis. Meanwhile, the interaction of 2-7 ligands with [(p-cymene)RuCl2]2 was analyzed in situ by UV-vis spectrophotometer. The in situ generated catalytic system derived from N-(2-(benzylideneamino)phenyl)-2,4,6-trimethyl-benzenesulfonamides and N-(2-(benzylamino)phenyl)-2,4,6-trimethyl-benzenesulfonamides with [(p-cymene)RuCl2]2 was used as a catalyst in the transfer hydrogenation (TH) of p-substituted acetophenone derivatives. The catalytic systems displayed high activities, which increased in the order 7<4<5<6<1<2<3. The best activity for the TH of 4-chloroacetophenone was provided with the [(p-cymene)RuCl2]2/ligand (3) catalytic system (turnover frequency values: 720 h(-1) for 10 min on S/C: 500/1).