The 1:1 stoichiometric reactions of 3-methoxy salicylaldehyde-4(N)-substituted thiosemicarbazones (H2L1-4) with [RuCpCI(PPh3)(2)] was carried out in methanol. The obtained complexes (1-4) were characterized by analytical, IR, absorption and H-1 NMR spectroscopic studies. The structures of ligand [H-2-3MSal-etsc] (H2L3) and complex [RuCp(Msal-etsc) (PPh3)] (3), were characterized by single crystal X-ray diffraction studies. The interaction of the ruthenium(II) complexes (1-4) with calfthymus DNA (CT-DNA) has been explored by absorption and emission titration methods. Based on the observations, an intercalative binding mode of DNA has been proposed. The protein binding abilities of the new complexes were monitored by quenching the tryptophan and tyrosine residues of BSA, as model protein. From the studies, it was found that the new ruthenium metallacycles exhibited better affinity than their precursors. The free radical scavenging assay suggests that all complexes effectively scavenged the DPPH radicals as compared to that of standard control ascorbic acid and scavenging activities of complexes are in the order of 4 > 2 >3 > 1. In addition, ruthenium(II) complexes (2-4) also exhibited an excellent in vivo antioxidant activity as it was able to increase the survival of worms exposed to lethal oxidative and thermal stresses possibly through reducing the intracellular ROS levels. It was interesting to note that complexes 2-4 failed to increase the lifespan of rnev-1 mutant worms having shortened lifespan due to the over production of free radicals. This data confirmed that complexes 2-4 conferred stress resistance in C. elegans, but they also require an endogenous detoxification mechanism for doing so. The genetic and reporter gene expression analysis revealed that complexes 2-4 maintained the intracellular redox status and offered stress protection through transactivation of antioxidant defence machinery genes gst-4 and sod-3 which are directly regulated by SKN-1 and DAF-16 transcription factors, respectively. Altogether, our results suggested that complexes 2-4 might play a crucial role in stress modulation and they perhaps exert almost similar effects in higher models, which is an important issue to be validated in future. (C) 2019 Elsevier Masson SAS. All rights reserved.

Four new cyclopentadienylruthenium(II)-acetophenone-4(N)-substituted thiosemi-carbazone complexes, with the general formula [Ru(eta(5)-C5H5)(H-Aptsc)PPh3]center dot Cl (1), [Ru(eta(5)-C5H5)(H-Apmtsc)PPh3]center dot Cl (2), [Ru(eta(5)-C5H5)(H-Ap-etsc)PPh3]center dot Cl (3) and [Ru(eta(5)-C5H5)(H-Ap-ptsc)PPh3]center dot Cl (4) were synthesised and characterised (H-1 NMR, C-13 NMR, IR and electronic spectroscopy). The molecular structure of representative complexes 2 and 3 was confirmed by single crystal X-Ray diffraction technique. The binding ability of complexes (1-4) to calf-thymus DNA (CT DNA) and Bovine Serum Albumin (BSA) has been explored by absorption and emission titration methods. Based on the observations, an electrostatic and an intercalative binding mode have been proposed for the complexes with CT-DNA. The BSA protein binding studies have been monitored by quenching of tryptophan and tyrosine residues in the presence of complexes and static type of quenching mechanism has been proposed. In vitro free radical scavenging activity was performed by DPPH radical. The complexes (1-4) exhibited highest scavenging activity than conventional standard vitamin C (IC50 = 5.65 +/- 0.12). Further, antibacterial activity of the complexes has been screened against four pathogenic bacteria such as Salmonella paratyphi, Staphylococcus aureus, Escherichia coli and Bacillus subtilis. From the results it is found that all the complexes exhibited significant activity against the pathogens and among them, complex 3 exhibited higher activity. (C) 2017 Elsevier B.V. All rights reserved.

New ruthenium(II) complexes were synthesised and characterized by various spectro analytical techniques. The structure of the complexes 3 and 4 has been confirmed by X-ray crystallography. The complexes were subjected to study their anti-oxidant profile and were exhibited significantly greater in vitro DPPH radical scavenging activity than vitamin C. We found that complexes 1–4 confered tolerance to oxidative stress and extend the mean lifespan of mev-1 mutant worms and wild-type Caenorhabditis elegans . Further, mechanistic study and reporter gene expression analysis revealed that Ru( ƞ 6 -p -cymene) complexes maintained the intracellular redox status and offers stress resistance through activating JNK-1/DAF-16 signaling axis and possibly by other antioxidant response pathway. Notably, complex 3 and 4 ameliorates the polyQ (a Huntington’s disease associated protein) mediated proteotoxicity and related behavioural deficits in Huntington’s disease models of C. elegans . From these observations, we hope that new Ru( ƞ 6 -p -cymene) complexes could be further considered as a potential drug to retard aging and age-related neurodegenerative diseases.

The current article deals with the preparation and characterisation of new organoruthenium(II) complexes, namely [RuCp(Dea-Sal-tsc)(PPh3)] (1), [RuCp(Dea-Sal-mtsc)(PPh3)] (2), [RuCp(Dea-Sal-etsc)(PPh3)] (3) and [RuCp(Dea-Sal-ptsc)(PPh3)] (4). The new ruthenium(II) complexes were characterized by various analytical, spectral techniques. The structure of the ligand [H2-Dea-Sal-tsc] and the complex [RuCp(Dea-Sal-tsc)(PPh3)] (1) were confirmed by X-ray crystallography. The complexes (1–4) were used to study the toxicity, stress resistance, aging and neuro-protective effects by taking Caenorhabditis elegans as model. In vitro free radical scavenging activity was performed by DPPH free radical scavenging assay, the complexes (1–4) exhibited highest scavenging activity than standard Vitamin C (IC50 = 5.28 ± 0.10). The lifespan has increased over 22.4% in mev-1 mutant worms treated with complex 4. The complex 4 triggered the DAF-16 nuclear localization, increases sod-3 expression and reduced amyloid (Aβ) protein induced paralysis were observed. In the present study we confirmed that oxidative stress resistance of N2 and lifespan extension of mev-1 mutant which showed the potential ROS scavenging activity of complex 4. The results also confirmed the effective anti-aging potential of ruthenium complex 4 which may be developed as a therapeutic drug for the prevention of aging and age related neurodegenerative diseases. Further studies are required to find out the exact action of complex 4 on higher model.

Cyclopentadienyl ruthenium(ii) thiosemicarbazone complexes with the formula [Ru(η5-C5H5)(Ac-tsc)PPh3]·Cl (1), [Ru(η5-C5H5)(Ac-mtsc)PPh3]·Cl (2), [Ru(η5-C5H5)(Ac-etsc)PPh3]·Cl (3) and [Ru(η5-C5H5)(Ac-ptsc)PPh3] (4) were synthesized and characterized by various spectroscopic techniques (1H NMR,13C NMR, IR and UV-vis).