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Guin P.S.,Shibpur Dinobundhoo Institution College | Mandal P.C.,Jadavpur University | Mandal P.C.,Saha Institute of Nuclear Physics | Das S.,Jadavpur University
Radiation Physics and Chemistry | Year: 2013

Radiation-induced double-strand modification of DNA was studied in the absence and presence of sodium 1,4-dihydroxy-9,10-anthraquinone-2-sulfonate (NaQSH2) and its metal (Cu2+ and Ni2+) complexes in aerated, de-aerated (Argon saturated) and N2O saturated aqueous media at pH 7.4. Ethidium bromide, an established DNA intercalator was used to estimate DNA remaining after interaction with γ-radiation, by measuring loss of fluorescence of the ethidium bromide-DNA adduct. In de-aerated (Argon saturated) and N2O saturated aqueous media radiation-induced double-strand modification of calf thymus DNA was comparatively less in presence of NaQSH2 and its Ni(II) complex than standard control indicating the compounds behaved as radio-protectors. However, in presence of the Cu(II) complex radiation-induced double-strand modification increased significantly. In N2O saturated medium, double-strand modification of DNA was almost double in all cases than that observed in de-aerated (Argon saturated) medium indicating OH radicals played a major role in modifying DNA. That OH radicals were important was verified by repeating experiments using tertiary-butanol that showed significant decrease in DNA modification. Another important observation was in aerated medium NaQSH2, Ni(II)-NaQSH2 did not show radioprotection while Cu(II)-NaQSH2 was an almost equally effective radiosensitizer as that observed in N2O saturated medium. Role of molecular oxygen as radiosensitizer was thus realized. © 2013 Elsevier Ltd. Source


Mahali K.,Kalyani University | Roy S.,Shibpur Dinobundhoo Institution College | Dolui B.K.,Visva Bharati
Journal of the Chinese Chemical Society | Year: 2014

In this article, we reported the solubilities of the amino acid DL-nor-valine (VAL) at five equidistant temeratures i.e. from 15 to 35 °C in aqueous mixtures of N,N-dimethyl formamide (DMF). The Standard free energies (ΔG Ot (i)) and entropies (ΔS Ot (i)) of transfer of VAL from water to aqueous mixture of cationophilic dipolar aprotic DMF have been evaluated at 25 °C. The transfer of Gibbs energies (ΔG Ot,ch (i)) and entropies (TΔS Ot,ch (i)) due to the chemical effects have been obtained after elimination of cavity effect, estimated by the scaled particle theory and dipole-dipole interaction effects, computed by the used of Keesom-orientation expression. The chemical contribution of transfer energetics of DL-nor-valine (VAL) are mainly guided by the composite effects of increased dispersion interaction, basicity effect and decreased acidity, hydrogen bonding effects, hydrophilic hydration and hydrophobic hydration of aqueous DMF mixtures as compared to that of reference solvent, water. In this article the transfer energetics of DL-nor-Valine, having long aliphatic hydrophobic moiety are computed at 25 °C in aqueous mixture of N,N-dimethyl formamide. The chemical contribution of transfer energetics of it are guided by the composite effects of increased dispersion interaction, basicity and decreased acidity, H-bonding effects, hydrophilic and hydrophobic hydration of aqueous DMF mixtures compared to water. Copyright © 2014 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany. Source


Guin P.S.,Shibpur Dinobundhoo Institution College | Mandal P.C.,Saha Institute of Nuclear Physics | Das S.,Jadavpur University
ChemPlusChem | Year: 2012

Anthracyclines are broad-spectrum antibiotics that are used against several human cancers. Hydroxy-9,10-anthraquinone compounds closely resemble anthracycline antibiotics from a structural and functional viewpoint. High cost and aspects of toxicity introduce limitations on its use. On complex formation the toxicities of anthracyclines decrease. A close analogue is sodium 1,4-dihydroxy-9,10-anthraquinone-2-sulphonate (AS), which is a comparatively cheaper molecule and resembles a good number of anthracycline derivatives. It forms a complex with Cu II, [Cu(AS) 2]. The complex interacts with calf thymus DNA that was studied by UV/Vis spectroscopy and cyclic vol-tammetry. The experimental data obtained from the two techniques was analyzed for binding constant and size of the binding site. These results not only corroborate each other but also justify earlier data obtained using fluorescence spectroscopy. An important aspect to this study was that nonlinear curve fitting, which is usually applied for analyzing DNA interaction using fluorescence and absorption spectroscopy, was used for the first time to analyze the interaction of the complex with DNA using cyclic voltammetry by monitoring the change in the reduction peak current (I p). The DNA binding data provides an insight into a probable mode of action of the hydroxy-9,10- anthraquinones within cells as modification of DNA that leads to cell death is an important aspect in cancer research. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Roy S.,Shibpur Dinobundhoo Institution College | Mahali K.,Kalyani University | Dolui B.K.,Visva Bharati
Journal of Solution Chemistry | Year: 2013

The standard Gibbs energies δt G° (i)) and entropies δt S°) of transfer in aqueous mixtures of 1,2-dimethoxyethane (DME) containing 0, 20, 40, 60, 80, 100 wt-% DME have been determined from the solubility data of a series of homologous α-amino acids, evaluated by the formol titrimetric method. The observed result of Δt G (i) and TΔt S° (i) against DME concentration profiles are complicated due to the various interaction effects. The chemical effects on the transfer Gibbs energies δt- grant° ch (i)) and entropies of transfer Tδ tS°ch (i) have been obtained after elimination of the cavity effect, calculated by the scaled particle theory, and dipole-dipole interaction effects, estimated by the use of Keesom-orientation expression for total transfer Gibbs energies Δt G° (i) and entropies Δt S°, respectively. The chemical transfer energetics of the zwitterionic homologous α-amino acids are guided by the composite effects of increased dispersion interaction, basicity and decreased acidity, hydrogen bonding capacity and hydrophobic hydration of the DME mixed solvent as compared to that of reference solvent, water. © 2013 Springer Science+Business Media New York. Source


Guin P.S.,Shibpur Dinobundhoo Institution College | Mandal P.C.,Saha Institute of Nuclear Physics | Das S.,Jadavpur University
Journal of Coordination Chemistry | Year: 2012

The anthracycline drug adriamycin and its metal complexes are efficient in treating several forms of human cancers with recognized antineoplastic activity attributed to strong interactions with DNA within the target cells. The hydroxy-9,10-anthraquinone unit present in the molecule controls and regulates drug action. Metal ions when linked to adriamycin help to reduce the generation of radicals responsible for toxic side effects. A complex of adriamycin with Ni(II) was prepared and its physicochemical characteristics and DNA-binding ability were compared to a Ni(II) complex of sodium-1,4-dihydroxy-9,10- anthraquinone-2-sulphonate (NaLH 2), an analog of adriamycin. Interactions with calf thymus DNA of both complexes were studied by UV-Vis and fluorescence spectroscopy. Binding parameters determined for both complexes agree with each other. Binding of the Ni(II)-adriamycin complex to DNA was five to eight times stronger than for the Ni(II) complex of the hydroxy-9,10- anthraquinone analog, Na 2[Ni(NaLH) 2Cl 2] ·2H 2O, i.e., Ni(NaLH) 2. The difference in binding was attributed to the presence of sugar units in adriamycin and to its absence in NaLH 2. Although the Ni(II) complex of the hydroxy-9,10- anthraquinone analog of adriamycin [Ni(NaLH) 2] was slightly weaker in binding DNA than the drug and its Ni(II) complex, a much lower cost of the former justifies its consideration as a substitute for the anthracycline drugs that are now in use. © 2012 Taylor & Francis. Source

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