Synthesis, characterization, DNA binding and cleavage properties and anticancer studies of ruthenium(III) Schiff base complexes

Biological Impacts of Metal(II) Complex-Based DNA Probes Derived from Bidentate N,O Donor Schiff Base Ligand

In this article, we have reported the preparation and structural characterization of a new Schiff base ligand (E)-2-(((2,6-difluorophenyl)imino)methyl)phenol (HSBL) and its derived metal(II) complexes [Cu(SBL)₂] (1), [Ni(SBL)₂] (2) and [Pd(SBL)₂] (3). Using various analytical and spectroscopic techniques, their structural properties have been appraised. The proposed chemical structure of HSBL has been confirmed by Single crystal XRD studies. Bidentate characteristic of HSBL and its coordination with metal(II) ions through the oxygen atom of the phenolic group and nitrogen atom of the azomethine group have been evaluated from the FT-IR spectral analysis. Pd(II) complex of HSBL (complex 3) has found to be efficient in bringing about the interaction with DNA as well as BSA molecules. The in vitro antimicrobial studies have been demonstrated that complex 3 has a superior antimicrobial activity than HSBL, complexes 1 and 2. According to the values of zone of inhibition, the antimicrobial ability has been increased in the order of 3 > 1 > 2 > HSBL. A significant decrease in percent cell viability has been suggested that complex 3 has remarkable cytotoxicity (IC₅₀ = 15.7 ± 0.6 μg/mL) on human breast cancer (MCF-7) cells. Besides, their induced apoptosis pathway of cytotoxicity has been demonstrated by fluorescence staining techniques using AO/EB staining method. We hope this article will be very helpful for future research on the development of new anticancer agents.

Synthesis, Characterization, Anticancer, and Antioxidant Studies of Ru(III) Complexes of Monobasic Tridentate Schiff Bases

Mononuclear Ru(III) complexes of the type [Ru(LL)Cl₂(H₂O)] (LL = monobasic tridentate Schiff base anion: (1Z)-N′-(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)-N-phenylethanimidamide [DAE], 4-[(1E)-N-{2-[(Z)-(4-hydroxy-3-methoxybenzylidene)amino]ethyl}ethanimidoyl]benzene-1,3-diol [HME], 4-[(1E)-N-{2-[(Z)-(3,4-dimethoxybenzylidene)amino]ethyl}ethanimidoyl]benzene-1,3-diol [MBE], and N-(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)benzenecarboximidoyl chloride [DEE]) were synthesized and characterized using the microanalytical, conductivity measurements, electronic spectra, and FTIR spectroscopy. IR spectral studies confirmed that the ligands act as tridentate chelate coordinating the metal ion through the azomethine nitrogen and phenolic oxygen atom. An octahedral geometry has been proposed for all Ru(III)-Schiff base complexes. In vitro anticancer studies of the synthesized complexes against renal cancer cells (TK-10), melanoma cancer cells (UACC-62), and breast cancer cells (MCF-7) was investigated using the Sulforhodamine B assay. [Ru(DAE)Cl₂(H₂O)] showed the highest activity with IC₅₀ valves of 3.57 ± 1.09, 6.44 ± 0.38, and 9.06 ± 1.18 μM against MCF-7, UACC-62, and TK-10, respectively, order of activity being TK-10 < UACC-62 < MCF-7. The antioxidant activity by DPPH and ABTS inhibition assay was also examined. Scavenging ability of the complexes on DPPH radical can be ranked in the following order: [Ru(DEE)Cl₂(H₂O)] > [Ru(HME)Cl₂(H₂O)] > [Ru(DAE)Cl₂(H₂O)] > [Ru(MBE)Cl₂(H₂O)].

Spectral, electrochemical, thermal, DNA binding ability, antioxidant and antibacterial studies of novel Ru(III) Schiff base complexes

Four new air stable low spin Ru(III) complexes of the type [Ru(L(1-4))(H2O)2]Cl have been synthesized, where L=dianion of the tetradentate Schiff base ligands namely N,N'bis(salicylaldehyde)4,5-dimethy-l,2-phenylendiammine (L(1)H2), N,N'bis(salicylaldehyde)4,5-dichloro 1,2-phenylendiammine (L(2)H2), N,N'bis(o-vanillin)4,5-dimethy-1,2-phenylendiammine (L(3)H2) and N,N'bis(o-vanillin)4,5-dichloro-1,2-phenylendiammine (L(4)H2). The complexes have been fully characterized by elemental analysis, infrared spectroscopy, electronic spectroscopy, magnetic susceptibility and electron spin resonance spectroscopy. Elemental analyses and spectroscopic data have been showed that, the stoichiometries of complexes were 1:1 with an octahedral geometry for all the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. The redox behavior of the complexes has been investigated by the cyclic voltammetric technique. The interaction of these complexes with calf thymus DNA (CT-DNA) was explored by different techniques which revealed that the complexes could bind to CT-DNA through an intercalative mode. Furthermore, the antioxidant activity of the Ru(III) complexes against superoxide and hydroxyl radicals was evaluated by using spectrophotometer methods in vitro. The experiments on antioxidant activity show that the complexes were found to possess potent antioxidant activity. Additionally, as a potential application the antibacterial activity of the complexes was assessed by testing their effect on the growth of various strains of bacteria.