Synthetic, characterization and cytotoxic studies of ruthenium complexes with Schiff bases encompassing biologically relevant moieties

This research study describes the formation and characterization of novel paramagnetic ruthenium complexes, cis-Cl, trans-P-[(RuCl2)-Cl-III (carboim)(PPh3)(2)] with bidentate chelating carbohydrazide Schiff bases (carboim = bpc for 1, ttc for 2 and tpc for 3). These metal complexes were synthesized by the equimolar coordination reactions of trans-[RuCl2(PPh3)(2)] with N-[1,3-benzothiazole-2-ylmethylidene]pyridine-2-carbohydrazide (Hbpc), N-((uracil-5-yl)methylene)thiophene-2-carbohydrazide (Httc) and N-[(uracil-5-yl)methylidenelpyridine-2-carbohydrazide (Htpc), respectively. Physicochemical techniques including nuclear magnetic resonance-, electron-spin resonance- and infrared spectroscopy, UV-Vis spectrophotometry, voltammetry as well as molar conductivity measurements provided definitive determinations of the respective ruthenium compounds' structures. The DPPH and NO radical scavenging capabilities of 1-3 and two previously reported ruthenium(II) complexes, trans-[RuCl(PPh3)(2)(Htdp)] (H(2)tdp = 5-((thiophen-3-yl)methyleneamino)-6-amino-1,3-dimethyluracil) (4) and [RuCl(PPh3)(H(3)ucp)] (H(4)ucp = 2,6-bis-((6-amino-1,3-dimethyluracilimino)methylene)pyridine) (5), were investigated. The calf-thymus DNA binding capabilities of 1-5 were explored using electronic spectroscopy and gel electrophoresis. In vitro anticancer studies showed that 1 and 2 were not active in the range tested, while 3-5 were toxic to HCC70 breast carcinoma cells, with 4 showing promising IC50 at 3.4 mu m. (C) 2020 Elsevier Ltd. All rights reserved.