Browsing by Author "Ruchi Gaur"

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A water soluble calcium-sodium based coordination polymer: Selective release of calcium at specific binding sites on proteins
(Royal Society of Chemistry, 2014) Ruchi Gaur; Ambadipudi Susmitha; K.V.R. Chary; Lallan Mishra
A calcium-sodium based water soluble coordination complex [{Ca 4Na(EGTA)2(H2O)13} n·NO3] (EGTA = ethylene bis(oxyethylenenitrilo) tetraaceticacid), henceforth named Ca/Na-1, has been synthesized hydrothermally and characterized using spectroscopic and single crystal X-ray diffraction techniques. Single crystal X-ray diffraction of the assembly affirms a two dimensional self assembled net-like supramolecular structure. The complex serves as a biological mimic of a calcium buffer and dispenses felicitous amounts of Ca2+ ions at the binding sites on proteins, as shown by SEM imaging and MALDI-TOF spectroscopy. The thermodynamics of binding has also been measured by isothermal titration calorimetry. Protein conformational changes have been characterized by NMR spectroscopy. © The Royal Society of Chemistry 2014.
Anticancer activity of two ruthenium(II)-DMSO-chalcone complexes: Comparison of cytotoxic, pro-apoptotic and antimetastatic potential
(Zerbinis Publications, 2016) Katarina K. Jovanovic; Nevenka Gligorijevic; Ruchi Gaur; Lallan Mishra; Sinisa Radulovic
Purpose: Recently, we reported the synthesis and characterization of two complexes of general formula cis-[Ru(S-DMSO)3(R-CO-CH=CH-R′)Cl] (R=2-hydroxyphenyl for both, R′=thiophene (1), 3-methyl thiophene (2)) that showed remarkable topoisomerase II inhibition and strong binding with DNA. The aim of this study was the investigation of cytotoxic properties of these complexes against a panel of human tumor cell lines, with elucidation of their anticancer mechanisms in HeLa cells. Methods: Characterization of anticancer activity of the investigated ruthenium complexes 1 and 2 included analysis of cytotoxicity by MTT assay. Cell cycle phase disruption of HeLa cells treated with complexes 1 and 2 was analyzed by flow cytometry after propidium iodide (PI) staining. Annexin V-FITC/PI double staining and further flow cytometry analysis and acridine orange (AO)/ethidium bromide (EB) double staining andfluorescent microscopy were used to determine the apoptotic potential of the investigated ruthenium complexes. The inhibitory effect on gelatinases (MMP-2 and MMP-9) as an indication of possible antimetastatic potential was also analyzed using gelatine zymography. Results: The 50% cell growth inhibition (IC50) values of the investigated complexes ranged between 22.9 and 76.8 μM, with complex 2 being more cytotoxic. Both complexes induced G2 phase cell cycle arrest and apoptosis in HeLa cells. Inhibitory effect of complex 2 on MMP-2 activity was detected. Conclusions: This work revealed the potential of the investigated Ru(II)-DMSO-chalcone complexes as anticancer agents with cytotoxic and pro-apoptotic activity and indicated complex 2 as leading compound for further chemical modifications and anticancer research. © 2016, Zerbinis Publications. All rights reserved.
Bi-nuclear Ru(ii) complexes of bis-chalcone and bis-flavonol: Synthesis, characterization, photo cleavage of DNA and Topoisomerase i inhibition
(Royal Society of Chemistry, 2013) Ruchi Gaur; Lallan Mishra
Complexes of type [Ru2(L1/L2)(DMSO) 6Cl2] (L1H2 = 1-(2-Hydroxy-phenyl)- 3-{4-[3-(2-hydroxy-phenyl)-3-oxo-propenyl]-phenyl}-propenone 1, L 2H2 = 1,4-bis-(3-hydroxy-4-oxo-4H-chromen-2-yl)-benzene) 2, are prepared and characterized using spectroscopic techniques. In complex 1, both ruthenium centres possess a similar coordination environment in which all S-dmso coordinate to ruthenium centres. However, in complex 2, one ruthenium centre is coordinated to three S-bonded dmso, and other ruthenium ion is coordinated to two S-bonded dmso and one O-bonded dmso. This difference in coordination around ruthenium centres in complex 2 is supported by two irreversible oxidation peaks observed at 0.84 V and 1.06 V and two MLCT transitions observed at λmax 485 and 565 nm in its cyclic voltammetry and UV-visible spectrum respectively. The interaction of complexes with Calf Thymus DNA (CT-DNA) is monitored using UV-vis titrations (K b = 2.1 × 106 M-1 for 1 and 1.3 × 105 M-1 for 2) and ethidium bromide displacement studies (Ksv = 1.37 and 0.98). The stronger binding of complex 1 with CT-DNA as compared to complex 2 could be attributed to its conjugated structural framework. In presence of complex 1 under photo-induced condition in visible region at λ 560 nm, supercoiled DNA is converted more in nicked circular form and supported its stronger binding with DNA as compared to complex 2. Complexes intercalate (1 stronger than 2) with DNA. They also prefer minor groove (1) and major groove (2) binding with DNA. Both complexes inhibit topoisomerase I relaxation activity at concentration > 50 μM. © The Royal Society of Chemistry 2013.
Interaction of a ruthenium(II)-chalcone complex with double stranded DNA: Spectroscopic, molecular docking and nuclease properties
(2011) Ruchi Gaur; Rais Ahmad Khan; Sartaj Tabassum; Priyanka Shah; Mohammad I. Siddiqi; Lallan Mishra
The interaction of a well characterized new complex 1 cis,fac-[RuCl(dmso-S) 3(L)] LH = 1-(2-hydroxyphenyl)-3-(4-chlorophenyl) propenone with Calf-thymus DNA (CT-DNA) is monitored using UV-vis titration (Kb = 3.8 × 107) and ethidium bromide displacement studies (K sv = 3.2). The molecular docking of the complex with DNA sequence d(ACCGACGTCGGT)2 reveals that complex is stabilized by additional electrostatic and hydrogen bonding interaction with DNA besides probable displacement of a labile DMSO by the N7 of guanine. The coordination of guanine is further supported by the isolation and characterization of its adduct with the complex 1.gua (gua = guanine). The nuclease property of complex 1 in the absence and presence of different activators and trappers demonstrates that complex efficiently cleaves supercoiled pBR322 plasmid DNA and binds through major groove of the DNA. © 2011 Elsevier B.V. All rights reserved.
Ruthenium complexes as precursors for chemical vapor-deposition (CVD)
(Royal Society of Chemistry, 2014) Ruchi Gaur; Lallan Mishra; M. Aslam Siddiqi; Burak Atakan
Ruthenium and its compounds are often used as thin films and can be deposited by chemical vapor deposition. The quality of the films strongly depends on the inorganic precursors, their evaporation behaviour and thermochemistry. This is an area where different aspects of inorganic chemistry and chemical engineering must fit together to provide good thin films. It was noticed that providing firsthand information in one place especially for a learner of this area of research, and collection of reports on different types of ruthenium complexes as CVD precursors would be timely. Thus, in this review a bird's eye view of ruthenium complexes suitable for CVD technology, together with the presentation of different precursors, their synthesis, evaporation, decomposition and film formation is presented. A brief summary of the CVD technique is also presented with future-design, synthesis and usefulness of CVD precursors. This journal is © the Partner Organisations 2014.
Structural and theoretical study of copper(ii) complex incorporating chalcone and 2,2′-bipyridine mixed ligands: a probable candidate for optical material
(Royal Society of Chemistry, 2022) Ruchi Gaur; Parashuram Kallem
A mixed ligand containing a Cu(ii) complex, CuM [Cu(L·bpy)(NO3)] {LH = 1-(2-hydroxyphenyl)-3-(3-methyl-2-thienyl)-2-propen-1-one, bpy = 2,2′-bipyridine}, has been synthesized and characterized using spectroscopy and X-ray crystallography. It forms an orthorhombic crystal system with space group, Pbca. The Cu(ii) metal exhibits slight distortion in a square pyramidal geometry in which an oxygen atom from the nitrate occupies the central apex, and the N2O2 core from chalcone and bipyridine form the basal plane. The crystal structure shows C-H⋯O, C-H⋯S and π-π weak non-covalent interactions and forms a chair-like 2D supramolecular architecture which is further analysed through hirshfeld surfaces, fingerprint plots and energy frameworks. The natural bond orbital, time dependent DFT and polarizability calculations are evaluated using the B3LYP/6-31G++(d,p) basis set for C, H, N, and O, and LANL2DZ set for copper. The DFT calculated nonlinear optical (NLO) responsive properties i.e. dipole moment (μ), polarizability (α), first hyperpolarizability (β), and second hyperpolarizability (γ) have promising values in gas as well as solvent phases (methanol, acetonitrile, water, DSMO). The NLO properties i.e. first and second hyperpolarizability (β, γ) of CuM in the gas phase are calculated as 20.36 × 10−30 esu and 2775.176 × 10−36 esu, respectively. The computed NLO properties enhance with solvent polarity. The calculated nonlinear optical properties indicate that CuM is a strong candidate for the fabrication of future optoelectronic devices. © 2022 The Royal Society of Chemistry.
Structural characterization and cytotoxicity studies of ruthenium(II)-dmso-chloro complexes of chalcone and flavone derivatives
(Elsevier Ltd, 2010) Rishikesh Prajapati; Santosh Kumar Dubey; Ruchi Gaur; Raj Kumar Koiri; Brajesh Kumar Maurya; Surendra Kumar Trigun; Lallan Mishra
A synthetic precursor cis-[RuIICl2(dmso)4] is complexed separately with 3-(4-benzyloxyphenyl)-1-(2-hydroxylphenyl)-prop-2-en-1-one (L1H) and 2-(4-benzyloxyphenyl)-3hydroxy-chromen-4-one (L2H). The resulting complexes are assigned the composition fac-[RuCl(S-dmso)3(L1)] 1 and fac-[RuCl(S-dmso)3(L2)] 2 using elemental analyses, FAB mass data and spectroscopic (IR, 1H NMR, UV-Vis, emission) spectral properties. The X-ray diffraction analysis shows that complexes self-associate through non-covalent interactions and provide 1D and 2D supramolecular structures. These complexes are assayed for their cytotoxicity studies on Dalton Lymphoma cell lines. © 2009 Elsevier Ltd. All rights reserved.
Supramolecular and theoretical investigation of copper(II) complexes containing 2,2′-bipyridine and substituted chalcone ligands: Estimation of non-covalent interactions
(Elsevier B.V., 2023) Ruchi Gaur; Lallan Mishra
Copper complexes of type [Cu(L)(bpy)(NO3)] {1, L = L1; 2, L = L2; L1H= 3-(4-benzyloxyphenyl)-1-(2-hydroxylphenyl)-prop-2-en-1-one, L2H= 1-(2-hydroxyphenyl)-3-(4-chlorophenyl) prop-2-en-1-one, bpy=2,2′-bipyridine} have been synthesized and characterized using elemental analysis, spectroscopic (IR, UV–Vis) and single crystal X-ray diffraction techniques. In both complexes, Cu(II) adopts distorted square pyramidal geometry. The crystal packing of complex 1 displays an infinite 1D supramolecular architecture using C–H⋯O and π-π stacking interactions. The C–H⋯O and π⋯π interactions together with weak C–H⋯Cl interaction facilitate formation of a 2D supramolecular net like structure in complex 2. The comprehensive studies of these interactions have been made using hirshfeld surface, fingerprint plots analyses and energy frameworks. The molecular electrostatic potential (MEP) surface analysis shows the larger values of negatively charged nitrate and larger positive values at aromatic ring in both complexes. It implies that C–H⋯O and π⋯π interactions are dominant. Additionally, the combination of non-covalent interaction (NCI) plot index and QTAIM analysis computational tools are used to explore energetic features of the synthons involving different non-covalent interactions such as C–H⋯O, π⋯π and C–H⋯Cl interactions. Both analyses show that the combined π⋯π and C–H⋯π interactions are dominant in the complex 1 for the dimer stabilization and construction of supramolecular structure. Whereas, complex 2 dimerization is prominently due to π⋯π interaction. The complexes 1 and 2 display emissions λmax 524 and 533 nm at λexcit 438 and 440 nm, respectively. It indicates small bathochromic shift in emission of complex 2 to complex 1 due to substituted chalcone ligands. © 2022 Elsevier B.V.
Synthesis and characterization of Ru(II)-DMSO-Cl-chalcone complexes: DNA binding, nuclease, and topoisomerase II inhibitory activity
(2012) Ruchi Gaur; Lallan Mishra
The complexes of type cis-[Ru(S-DMSO) 3(R-CO-CH-CH-R′)Cl] (R = 2-hydroxyphenyl for all, R′ = phenyl 1, naphthyl 2, anthracenyl 3, thiophene 4, 3-methyl thiophene 5) are synthesized and characterized using spectroscopic (IR, 1H and 13C NMR, and UV-vis) and single crystal X-ray diffraction techniques. Their crystal structures show the formation of both intermolecular and intramolecular H-bonding. The molecular assembly of complex 5 using secondary interactions provides a butterfly structure. The binding of complexes with calf thymus DNA is monitored using UV-vis spectral titrations. The binding interaction of complexes 1, 2, and 3 with DNA increases with increasing conjugation of aromatic rings. However, complexes 4 and 5 interact with DNA strongly. The emission from ethidium bromide (EB) bound DNA recorded in phosphate buffer solution (pH = 7.2) decreases by incremental addition of solution of the complexes. The complexes 4 and 5 (100 μM) bind with the minor groove of DNA and cleave double-stranded pBR322 DNA significantly even in the absence of an activator. In the presence of H 2O 2, they cleave supercoiled DNA via oxidative pathway even at lower concentration (20 μM). Both complexes 4 and 5 inhibit topoisomerase II activity with IC 50 values of 18 and 13. These values suggest that 4 and 5 are potential topoisomerase II inhibitors as compared to some of known inhibitors like novobiocin and etoposide. © 2012 American Chemical Society.
Synthesis, structures, nuclease activity, cytotoxicity, DFT and molecular docking studies of two nitrato bridged homodinuclear (Cu-Cu, Zn-Zn) complexes containing 2,2′-bipyridine and a chalcone derivative
(Elsevier B.V., 2017) Ruchi Gaur; Diksha Kumari Choubey; Mohammad Usman Azam; Benzamin D. Ward; Jagat Kumar Roy; Lallan Mishra
Nitrato briged dinuclear complexes of type [Cu2(L)2(bpy)2(NO3)](NO3)·4H2O, 1 and [Zn2(L)2(bpy)2(NO3)](NO3)·4H2O, 2 (L = deprotonated form of free ligand LH, [1-(2-hydroxyphenyl)-3-(9-anthracenyl) propenone; bpy = 2,2′bipyridine] are synthesized and characterized using a battery of physicochemical techniques and X-ray crystallography. A distorted square pyramidal geometry is assigned to them with N2O3 coordination core around the metal ion. The co-ligand L binds the metal ions through its O,O' atoms in anti-syn mode. The metal centers in complexes 1 and 2 are separated via bridging nitrato group at a distance of 6.073 Å and 5.635 Å respectively. Their structures and absorption spectra are supported by the computational studies using density functional theory (DFT) and TD-DFT. Both complexes exhibit nuclease activity and cleave supercoiled (form I) DNA. The complex 1 preferentially binds major groove of DNA and follows an oxidative pathway whereas complex 2 binds with minor groove of DNA via hydrolytic pathway. Both complexes inhibit topoisomerase I relaxation activity with IC50 values of 7 and 35 μM. Molecular docking studies support the groove binding and topoisomerase I binding of the complexes. The complex 1 showed a significant cytotoxicity against HeLa cell lines (a cervical cancer cell lines) in vitro with IC50 value calculated as 2.9 ± 0.021 μM as compared to 28.2 ± 0. 044 μΜ for complex 2. Complex 2 induces the cell apoptosis at a later-stage as compared to complex 1. The cell apoptosis and topoisomerase inhibition by complexes enable them to be potential candidates as future anticancer drugs. © 2017
The Flavonoid Derivative 2-(4′ Benzyloxyphenyl)-3-hydroxy-chromen-4-one Protects Against Aβ42-Induced Neurodegeneration in Transgenic Drosophila: Insights from In Silico and In Vivo Studies
(Springer Science and Business Media, LLC, 2014) Sandeep Kumar Singh; Ruchi Gaur; Akhil Kumar; Roshan Fatima; Lallan Mishra; Saripella Srikrishna
In the pathogenesis of Alzheimer’s disease (AD), it is well established that the self-association of Aβ peptides into amyloid fibrils and/or plaque like aggregates causes neurotoxicity. As there is no cure for AD till date, identification of specific compounds that either inhibit the formation of Aβ-fibrils or help in the dissolution of already formed amyloid plaques makes an appealing therapeutic and preventive strategy in the development of drugs. In the present study, four synthetic flavonoid derivatives (1, 2, 3 and 4) were examined for docking studies with Amyloid beta (PDB Code: 1IYT) and Amyloid fibril (PDB Code: 2BEG). Of these, compound 1 and 4 were found to be potential inhibitors, as supported by computational molecular docking studies with adequate pharmacokinetic properties. Compound 1 was further tested in vivo in transgenic AD model of Drosophila. The disease causing human Aβ42 peptide was expressed in the compound eye by driving UAS-Aβ42 with ey-GAL4, which caused severe degeneration in eye tissues ranging from loss of bristles, ommatidial holes to severe ommatidial disruption as revealed by digital camera imaging and scanning electron microscopy. When the Aβ42 expressing larvae were grown in medium containing Compound 1, ~70 % rescue of the rough eye phenotype was observed at 75 and 100 μM concentrations. This is further corroborated by significant reduction in amyloid plaques in eye imaginal disks of compound 1 treated larvae as revealed by immuno-confocal imaging studies. Further, rescue of locomotor deficit and improved life span in compound 1 treated Aβ flies also confirm the neuroprotective activity of this compound. Thus, our results support the neuroprotective efficacy of compound 1 in preventing Aβ42-induced neurotoxicity in vivo and identify it as a future therapeutic agent against AD. © 2014, Springer Science+Business Media New York.