Human vaccinia H1-related phosphatase (VHR) is a dual-specific phosphatase (DSPs) that plays an important role in the mitogen-activated protein (MAP) kinase cascade regulation. It is also a potential drug target for diseases that are related to immune response. By combining a virtual and NMR-based ligand-screening strategy, we successfully identified four VHR inhibitors, of which GATPT ((glucosamine-aminoethoxy)triphenyltin) can bind to VHR with a K(i) value of 2.54 muM. The putative binding mode of GATPT was constructed by a molecular docking simulation to provide structural insights into the ligand-binding mechanism. Furthermore, we found that this compound can significantly inhibit the dephosphorylation of the extracellular regulated kinases (ERKs), and c-Jun N-terminal kinases (JNKs) and block the G(1)-S phase transition in the cell cycle. Therefore, GATPT is a promising lead structure for designing more effective inhibitors of VHR.

Dinuclear complexes Bis [aqua 1,8-(1,2-dicarboxamido benzene) 3,6-diazaoctane copper (II)/nickel (II)] tetrachloride (1 and 2) were synthesized by a two component one-pot metal template condensation between phthalic anhydride and 1,8-diamino 3,6-diazaoctane. Elemental analysis, molar conductance measurements, electronic absorption, infra-red, electron paramagnetic resonance, nuclear magnetic resonance, atomic absorption, and electron spray mass spectral studies have been performed to probe the nature and structure of the complexes. The interaction of copper (II) complex with calf thymus (CT-DNA) has been studied by using absorption, emission and circular dichoric spectral methods, viscometry, and cyclic voltammetry. A strong hyperchromism along with a red shift in UV bands and hypochromism in the ligand field band of the complex 1 on interaction with CT-DNA imply a covalent mode of DNA binding. This is further confirmed by studying the reactivity of complex 1 using circular dichroism and viscosity measurements. The variation in relative emission intensity of DNA-bound ethidium bromide observed upon treatment with the complex 1 parallel the trend of DNA binding studies. Cyclic voltammetry studies reveal that the complex 1 prefers to bind to DNA in Cu(II) rather than Cu(I) oxidation state.

The novel organotin complex 1-{(2-hydroxyethyl)amino}-2-amino-1,2-dideoxy-D-glucose triphenyltin(iv) (GATPT) was synthesized by the reaction of N-glycoside ligand and triphenyltin(iv) chloride. GATPT was characterized by elemental analyses, polarimetry, IR, CD, UV and multinuclear ((1)H, (13)C, (119)Sn) 1D and 2D NMR. The interaction of GATPT with calf thymus DNA was studied by using viscometry, absorption, emission and circular dichoric spectral methods. The DNA binding results suggested the intercalative mode of binding for GATPT with DNA along with simultaneous electrostatic interaction between the Sn(iv) center and the phosphate backbone of the DNA helix. GATPT was tested for its cytotoxic properties against SY5Y, PC-12 and N2A neuronal tumor cell lines. GATPT induced significant apoptosis in the PC-12 cell line characterized by DNA fragmentation and chromosome condensation. Treatment of PC-12 cells with GATPT resulted in a dramatic up-regulation of Bax and Bak and down-regulation of the anti-apoptotic factor Bcl-2. Apoptotic induction by GATPT was shown to be mediated in a p53-dependent manner and loss of p53 impaired the release of cytochrome c from mitochondria to cytosol. Caspase-3 was found to be indispensable for the GATPT triggered apoptosis signaling pathway. Furthermore, in vivo studies using a nude mice model revealed that GATPT exhibits significant antiproliferative activity against tumor development with minimal cytotoxicity. These findings warrant further clinical investigations of GATPT as a therapeutic agent for cancer chemotherapy.

The new homodinuclear complexes 1-4 of the type [LMhave been synthesized and characterized by elemental analysis and various spectroscopic techniques. The homodinuclear complexes possess two different environments (N 2 and N 2 O 2 donor sets) for holding the metal ions. The metal ion in N 2 set exhibits square planar geometry with two chloride ions in the inner sphere but rhombic structure is found in tetradentate N 2 O 2 Schiff base cavity while in heterotrinuclear complexes Sn IV atom is in the octahedral environment. The interaction of complexes 1 and 5 with calf thymus DNA was carried out by absorption spectroscopy and cyclic voltammetry. The intrinsic binding constants (K b ) of complex 1 and 5 were determined as 3.2 × 10 3 M −1 and 9.6 × 10 3 M −1 , respectively suggesting that complex 5 binds more strongly to CT-DNA than complex 1. Fluorescence studies along with viscosity measurements have also been checked to authenticate the binding of metal complexes with DNA.

Programmed cell death (apoptosis) refers to a specific type of cell death under stringent genetic control. Even a slight alteration in this process leads to malformations characterized by birth defects. Based on the above hypothesis we deduced that apoptosis plays an important role in mediating the teratogenicity of cyclophosphamide in vitro. The present study was undertaken to see whether this phenomenon holds true or not. In this study, 11-day-old rat embryos were cultured for 24 hours with various concentrations of CP (i.e. 0, 5, 10 and 100 mug/ml culture). After culturing for 24 hours, embryos exposed to 10 and 100 mug/mL culture of CP were found having both malformations and growth retardation. Exposure to CP at 5 mug/mL culture did not show significant effect on embryonic development. Parallel to this, flow cytometric analysis (cell cycle and annexin V binding) and DNA fragmentation assay were also carried out followed by quantitation by 3'-OH labeling of cultured embryos to evaluate CP-induced apoptosis. All the results were found to be dose-dependant, and the data suggested that apoptosis is involved in mediating the teratogenicity of CP in vitro.