Browsing by Author "Santosh K. Dubey"

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Mixed-ligand Ru(II) complexes with 2,2′-bipyridine and aryldiazo-β-diketonato auxillary ligands: Synthesis, physico-chemical study and antitumour properties
(Elsevier Inc., 2005) Lallan Mishra; Ajay K. Yadaw; Subrato Bhattacharya; Santosh K. Dubey
The complexes of Ru(II)-2,2′-bipyridyl with substituted diazopentane-2,4-diones (L1H-L5H) were synthesized and characterized by elemental analyses, conductance, FAB (fast atom bombardment) mass and spectral (IR, UV/Vis (UV/visible), NMR) studies. Molecular geometry optimization of the complexes was also made. None of the complexes luminesce. However, facilitated oxidation of Ru(II) to Ru(III) was evidenced from their lower reduction potential data. The ligands and their complexes were tested for their antitumour activity against a variety of tumour cell lines. Though activity is found to vary with the type of tumour cell lines used, yet complex 5 with naphtyldiazopentane-2,4-dione as co-ligand was found to be a potential compound as it showed in general significant activity against all cell lines studied. © 2005 Elsevier Inc. All rights reserved.
Regression of Dalton's lymphoma in vivo via decline in lactate dehydrogenase and induction of apoptosis by a ruthenium(II)-complex containing 4-carboxy N-ethylbenzamide as ligand
(2009) Raj K. Koiri; Surendra K. Trigun; Lallan Mishra; Kiran Pandey; Deobrat Dixit; Santosh K. Dubey
Summary: A novel ruthenium(II)-complex containing 4-carboxy N-ethylbenzamide (Ru(II)-CNEB) was found to interact with and inhibit M4-lactate dehydrogenase (M4-LDH), a tumor growth supportive enzyme, at the tissue level. The present article describes modulation of M4-LDH by this compound in a T-cell lymphoma (Dalton's Lymphoma: DL) vis a vis regression of the tumor in vivo. The compound showed a dose dependent cytotoxicity to DL cells in vitro. When a non toxic dose (10 mg/kg bw i.p.) of Ru(II)-CNEB was administered to DL bearing mice, it also produced a significant decline in DL cell viability in vivo. The DL cells from Ru(II)-CNEB treated DL mice showed a significant decline in the level of M4-LDH with a concomitant release of this protein in the cell free ascitic fluid. A significant increase of nuclear DNA fragmentation in DL cells from Ru(II)-CNEB treated DL mice also coincided with the release of mitochondrial cytochrome c in those DL cells. Importantly, neither blood based biochemical markers of liver damage nor the normal patterns of LDH isozymes in other tissues were affected due to the treatment of DL mice with the compound. These results were also comparable with the effects of cisplatin (an anticancer drug) observed simultaneously on DL mice. The findings suggest that Ru(II)-CNEB is able to regress Dalton's lymphoma in vivo via declining M4-LDH and inducing mitochondrial dysfunction-apoptosis pathway without producing any toxicity to the normal tissues. © 2008 Springer Science+Business Media, LLC.
Ruthenium complex as enzyme modulator: Modulation of lactate dehydrogenase by a novel ruthenium(II) complex containing 4-carboxy N-ethylbenzamide as a ligand
(2007) Surendra K. Trigun; Raj K. Koiri; Lallan Mishra; Santosh K. Dubey; Santosh Singh; Pankaj Pandey
Ruthenium complex-protein interaction, particularly with respect to modulation of the enzymes associated to tumor development, is an evolving concept in understanding the mechanism of action of these complexes as anticancer agent. Lactate dehydrogenase (LDH; EC: 1.1.1.27) is critically implicated in maintaining tumor growth via 'Warburg effect' in cancerous cells. This article presents current status of Rucomplexes as enzyme inhibitors in general and a state of art on a novel ruthenium(II) complex containing 4-Carboxy-N-ethylbenzamide as an inhibitor of LDH. The 4-carboxy-N-ethylbenzamide (CNEB) was synthesized and characterized by single crystal X-ray measurement and complexed with cis-Ru(bpy)2Cl2.2H2O (bpy=2,2′bipyridine) resulting into synthesis of a [Ru(CNEB)2(bpy)2] 2PF6.0.5 NH4PF6] complex, Ru(II)-CNEB. The complex showed appreciable cytotoxicity on Dalton's lymphoma cells and a significant Ru(II)-CNEB-LDH interaction (Kc = 1.525 × 105 M-1). The later was further confirmed from luminescence quenching and gel retardation assays. The complex also caused a significant decline in the activities of purified LDH and LDH from mice liver extract. The complex was further characterized as a non-competitive inhibitor of LDH(Ki = 0.032 mM). Ru(II)-CNEB complex perfused mice liver also showed a significant decline in LDH activity coinciding with similar changes in the intensity of LDH bands on polyacrylamide gel electrophoresis. Thus, Ru(II)-CNEB complex, as a non-competitive inhibitor of LDH, seems to be a candidate for potential therapeutic applications. © 2007 Bentham Science Publishers Ltd.
Tuned helical array of RhIII/IrIII Cp* complexes with polypyridyl ligands
(Wiley-VCH Verlag, 2006) Sanjay K. Singh; Manish Chandra; Santosh K. Dubey; Daya S. Pandey
Reactions of the chloro-bridged dimeric complexes [{(η5- C5Me5)M(μ-Cl)Cl}2] (M = Rh, Ir) with the polypyridyl ligands 2,3-di(2-pyridyl)pyrazine (dpp) and 2,4,6-tri(2-pyridyl)-1, 3,5-triazine (tptz) in the presence of ammonium tetrafluoroborate gave the mononuclear complexes [(η5-C5Me5) MCl(κ2-dpp)]BF4 [M = Rh (1), Ir (2)] and [(η5-C5Me5)MCl(κ2-tptz)] BF4 [M = Rh (3), Ir (4)]. The complexes have been characterised by elemental analysis, FAB-MS, ESMS, IR, NMR, electronic and emission spectroscopic studies and the molecular structures of 1, 2 and 3 have been crystallographically determined. Structural studies on the complexes revealed the presence of helical superstructures resulting from C-H⋯X (X = N, F, Cl and π) interactions. © Wiley-VCH Verlag GmbH & Co. KGaA, 2006.