Ru(II)‑<i>p</i>‑Cymene Complexes of Furoylthiourea Ligands for Anticancer Applications against Breast Cancer Cells

Half-sandwich Ru(II) complexes containing nitro-substituted furoylthiourea ligands, bearing the general formula [(η6-p-cymene)RuCl2(L)] (1–6) and [(η6-p-cymene)RuCl(L)(PPh3)]+ (7–-12), have been synthesized and characterized. In contrast to the spectroscopic data which revealed monodentate coordination of the ligands to the Ru(II) ion via a “S” atom, single crystal X-ray structures revealed an unusual bidentate N, S coordination with the metal center forming a four-membered ring. Interaction studies by absorption, emission, and viscosity measurements revealed intercalation of the Ru(II) complexes with calf thymus (CT) DNA. The complexes showed good interactions with bovine serum albumin (BSA) as well. Further, their cytotoxicity was explored exclusively against breast cancer cells, namely, MCF-7, T47-D, and MDA-MB-231, wherein all of the complexes were found to display more pronounced activity than their ligand counterparts. Complexes 7–12 bearing triphenylphosphine displayed significant cytotoxicity, among which complex 12 showed IC50 values of 0.6 ± 0.9, 0.1 ± 0.8, and 0.1 ± 0.2 μM against MCF-7, T47-D, and MDA-MB-231 cell lines, respectively. The most active complexes were tested for their mode of cell death through staining assays, which confirmed apoptosis. The upregulation of apoptotic inducing and downregulation of apoptotic suppressing proteins as inferred from the western blot analysis also corroborated the apoptotic mode of cell death. The active complexes effectively generated reactive oxygen species (ROS) in MDA-MB-231 cells as analyzed from the 2′,7′-dichlorofluorescein diacetate (DCFH-DA) staining. Finally, in vivo studies of the highly active complexes (6 and 12) were performed on the mice model. Histological analyses revealed that treatment with these complexes at high doses of up to 8 mg/kg did not induce any visible damage to the tested organs

Ru(II)‑<i>p</i>‑Cymene Complexes of Furoylthiourea Ligands for Anticancer Applications against Breast Cancer Cells

Half-sandwich Ru(II) complexes containing nitro-substituted furoylthiourea ligands, bearing the general formula [(η6-p-cymene)RuCl2(L)] (1–6) and [(η6-p-cymene)RuCl(L)(PPh3)]+ (7–-12), have been synthesized and characterized. In contrast to the spectroscopic data which revealed monodentate coordination of the ligands to the Ru(II) ion via a “S” atom, single crystal X-ray structures revealed an unusual bidentate N, S coordination with the metal center forming a four-membered ring. Interaction studies by absorption, emission, and viscosity measurements revealed intercalation of the Ru(II) complexes with calf thymus (CT) DNA. The complexes showed good interactions with bovine serum albumin (BSA) as well. Further, their cytotoxicity was explored exclusively against breast cancer cells, namely, MCF-7, T47-D, and MDA-MB-231, wherein all of the complexes were found to display more pronounced activity than their ligand counterparts. Complexes 7–12 bearing triphenylphosphine displayed significant cytotoxicity, among which complex 12 showed IC50 values of 0.6 ± 0.9, 0.1 ± 0.8, and 0.1 ± 0.2 μM against MCF-7, T47-D, and MDA-MB-231 cell lines, respectively. The most active complexes were tested for their mode of cell death through staining assays, which confirmed apoptosis. The upregulation of apoptotic inducing and downregulation of apoptotic suppressing proteins as inferred from the western blot analysis also corroborated the apoptotic mode of cell death. The active complexes effectively generated reactive oxygen species (ROS) in MDA-MB-231 cells as analyzed from the 2′,7′-dichlorofluorescein diacetate (DCFH-DA) staining. Finally, in vivo studies of the highly active complexes (6 and 12) were performed on the mice model. Histological analyses revealed that treatment with these complexes at high doses of up to 8 mg/kg did not induce any visible damage to the tested organs

Water-Soluble Mono- and Binuclear Ru(η⁶‑<i>p</i>‑cymene) Complexes Containing Indole Thiosemicarbazones: Synthesis, DFT Modeling, Biomolecular Interactions, and <i>In Vitro</i> Anticancer Activity through Apoptosis

Indole thiosemicarbazone ligands were prepared from indole-3-carboxaldehyde and <i>N</i>-(un)­substituted thiosemicarbazide. The Ru­(η⁶-<i>p</i>-cymene) complexes [Ru­(η⁶-<i>p</i>-cymene)­(HL1)­Cl]Cl (<b>1</b>) and [Ru­(η⁶-<i>p</i>-cymene)­(L2)]₂Cl₂ (<b>2*</b>) were exclusively synthesized from thiosemicarbazone (TSC) ligands HL1 and HL2, and [RuCl₂(<i>p-</i>cymene)]₂. The compounds were characterized by analytical and various spectroscopic (electronic, FT-IR, 1D/2D NMR, and mass) tools. The exact structures of the compounds (HL1, HL2, <b>1</b>, and <b>2*</b>) were confirmed by single-crystal X-ray diffraction technique. In complexes <b>1</b> and <b>2*</b>, the ligand coordinated in a bidentate neutral (<b>1</b>)/monobasic (<b>2*</b>) fashion to form a five-membered ring. The complexes showed a piano-stool geometry around the Ru ion. While <b>2*</b> existed as a dimer, <b>1</b> existed as a monomer, and this was well explained through free energy, bond parameter, and charge values computed at the B3LYP/SDD level. The intercalative binding mode of the complexes with calf thymus DNA (CT DNA) was revealed by spectroscopic and viscometric studies. The DNA (pUC19 and pBR322 DNA) cleavage ability of these complexes evaluated by an agarose gel electrophoresis method confirmed significant DNA cleavage activity. Further, the interaction of the complexes with bovine serum albumin (BSA) was investigated using spectroscopic methods, which disclosed that the complexes could bind strongly with BSA. A hemolysis study with human erythrocytes revealed blood biocompatibility of the complexes. The <i>in vitro</i> anticancer activity of the compounds (HL1, HL2, <b>1</b>, and <b>2*</b>) was screened against two cancer cell lines (A549 and HepG-2) and one normal cell line (L929). Interestingly, the binuclear complex <b>2*</b> showed superior activity with IC₅₀ = 11.5 μM, which was lower than that of cisplatin against the A549 cancer cell line. The activity of the same complex (IC₅₀ = 35.3 μM) was inferior to that of cisplatin in the HepG-2 cancer cell line. Further, the apoptosis mode of cell death in the cancer cell line was confirmed by using confocal microscopy and DNA fragmentation analysis