Showing papers in "Bioinorganic Chemistry and Applications in 2012"
TL;DR: In this paper, the authors summarized the mode of action of cisplatin on the tumor cells, a brief outlook on the metallocene compounds as antitumor drugs as well as the future tendencies for the use of the latter in anticancer chemotherapy.
Abstract: The purpose of this paper is to summarize mode of action of cisplatin on the tumor cells, a brief outlook on the metallocene compounds as antitumor drugs as well as the future tendencies for the use of the latter in anticancer chemotherapy. Molecular mechanisms of cisplatin interaction with DNA, DNA repair mechanisms, and cellular proteins are discussed. Molecular background of the sensitivity and resistance to cisplatin, as well as its influence on the efficacy of the antitumor immune response was evaluated. Furthermore, herein are summarized some metallocenes (titanocene, vanadocene, molybdocene, ferrocene, and zirconocene) with high antitumor activity.
121 citations
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TL;DR: This special issue presents a collection of papers dealing with different compounds/materials investigated for antitumoral, antimicrobial, and antifungal activity as well as DNA binding study.
Abstract: Metals in medicine are bridging the areas of inorganic chemistry and medicine. Metal-based materials, metallodrugs, and agents for treating and detecting diseases, their synthesis, structure, and general properties, as well as biological applications on cellular and living system level, are of great importance. The mechanisms of action and the roles of these metal compounds in cellular regulation and signaling in health and diseases are of principal interest. These areas are linked by the need to involve researchers having a deep understanding of inorganic chemistry in medically relevant research. This special issue presents a collection of papers dealing with different compounds/materials investigated for antitumoral, antimicrobial, and antifungal activity as well as DNA binding study.
Y. Li et al. reported on the efficient and specific method for the determination of diphenyl-di-(2,4-difluobenzohydroxamato)tin(II), DPDFT, in rat plasma. Their preliminary studies indicated nonlinearity pharmacokinetics in the investigated dose ranges in rats and that the concentration-time curves of DPDFT in rat plasma could be fitted to two-compartment model. Additionally, results hinted that DPDFT might accumulate in certain organs, thus producing the toxicity, or could be quickly metabolized in the plasma into active antitumoral constituents.
The synthesis and characterization of novel salicylaldehyde-derived ligands and corresponding Cu(II), Co(II), Ni(II), and Zn(II) complexes are described by Kursunlu et al. Ligands bearing chlorine, bromine and –OH substituents showed moderate inhibition activity against some Gram-positive and Gram-negative bacteria including methicillin-resistant Staphylococcus aureus. Ni(II) and Zn(II) complexes were generally more effective against tested bacteria than Cu(II) and Co(II) complexes.
In the work of A. A. Al-Amiery et al., significant antifungal activity of Cu(II), Co(II), and Ni(II) complexes with (Z)-2-(pyrrolidin-2-ylidene)hydrazinecarbothioamide and chloride ligands is described. The complexes were found to be superior antioxidants compared to ascorbic acid.
Zietz et al. evaluated Cu release characteristics from Cu doped titanium alloy (Ti6Al4V) of antimicrobial implant surfaces in vitro according to the storage fluid and surface roughness. Plasma immersion ion implantation of Cu (Cu-PIII) and pulsed magnetron sputtering process of a titanium copper film (Ti-Cu) were applied to Ti6Al4V samples with different surface finishing of the implant material (polished, hydroxyapatite, and corundum blasted). The Cu concentration in the supernatant was measured using atomic absorption spectrometry.
M. Rezaee et al. investigated the optimum experimental conditions to prepare dry thin films of Pt compounds bound to plasmid DNA on a Ta substrate. Their results show that used conditions can induce damage to DNA and highly sensitize them to manipulations required to form thin films and recover DNA from the Ta substrate. The concentration of intact DNA increases significantly in the film samples when used lower incubation temperature and shorter incubation time. Thus, the optimum condition is obtained from equilibrium between temperature, time, and Pt-compounds concentration during the DNA platination reaction.
In the review by S. Gomez-Ruiz et al., the mode of action of cisplatin against tumor cells as well as a brief outlook on the metallocene compounds as antitumor drugs and future tendencies for the use of the latter in anticancer chemotherapy are summarized. The authors reported on the molecular mechanisms of cisplatin interaction with DNA, DNA repair mechanisms, and cellular proteins. Molecular background of the sensitivity and resistance to cisplatin as well as its influence on the efficacy of the antitumor immune response were evaluated. Moreover, the use and mechanism of some metallocenes (titanocene, vanadocene, molybdocene, ferrocene and zirconocene) with high antitumor activity are reported.
119 citations
TL;DR: Metal complexes of (Z)-2-(pyrrolidin-2-ylidene)hydrazinecarbothioamide with Cu(II, Co(II), and Ni(II) chlorides were tested against selected types of fungi and were found to have significant antifungal activities.
Abstract: Metal complexes of (Z)-2-(pyrrolidin-2-ylidene)hydrazinecarbothioamide (L) with Cu(II), Co(II), and Ni(II) chlorides were tested against selected types of fungi and were found to have significant antifungal activities The free-radical-scavenging ability of the metal complexes was determined by their interaction with the stable free radical 2,2′′-diphenyl-1-picrylhydrazyl, and all the compounds showed encouraging antioxidant activities DFT calculations of the Cu complex were performed using molecular structures with optimized geometries Molecular orbital calculations provide a detailed description of the orbitals, including spatial characteristics, nodal patterns, and the contributions of individual atoms
108 citations
TL;DR: An overview of surface treatment methods, including coating with hydroxyapatite (HAp), an osteoconductive compound, is outlined, and evaluation by implantation of surface-modified samples in rat tibiae is described.
Abstract: Many techniques for the surface modification of titanium and its alloys have been proposed from the viewpoint of improving bioactivity. This paper contains an overview of surface treatment methods, including coating with hydroxyapatite (HAp), an osteoconductive compound. There are two types of coating methods: pyroprocessing and hydroprocessing. In this paper, hydroprocessing for coating on the titanium substrate with HAp, carbonate apatite (CO3–Ap), a CO3–Ap/CaCO3 composite, HAp/collagen, and a HAp/gelatin composite is outlined. Moreover, evaluation by implantation of surface-modified samples in rat tibiae is described.
106 citations
TL;DR: Both immobilized and free enzymes acted optimally at 50°C for removal of crystal violet, but the entrapped enzyme showed higher thermal stability compared to the free enzyme, and the immobilized enzyme represented optimum decolorization at pH 8.5.
Abstract: Alginate-gelatin mixed gel was applied to immobilized laccase for decolorization of some synthetic dyes including crystal violet. The immobilization procedure was accomplished by adding alginate to a gelatin solution containing the enzyme and the subsequent dropwise addition of the mixture into a stirred CaCl2 solution. The obtained data showed that both immobilized and free enzymes acted optimally at 50°C for removal of crystal violet, but the entrapped enzyme showed higher thermal stability compared to the free enzyme. The immobilized enzyme represented optimum decolorization at pH 8. Reusability of the entrapped laccase was also studied and the results showed that ca. 85% activity was retained after five successive cycles. The best removal condition was applied for decolorization of seven other synthetic dyes. Results showed that the maximum and minimum dye removal was related to amido black 10B and eosin, respectively.
91 citations
TL;DR: The biosorption of mercury (II) on 14 fungal biomasses, Aspergillus flavus I–V, As pergillus fumigatus I-II, Helminthosporium sp.
Abstract: The biosorption of mercury (II) on 14 fungal biomasses, Aspergillus flavus I–V, Aspergillus fumigatus I-II, Helminthosporium sp, Cladosporium sp, Mucor rouxii mutant, M rouxii IM-80, Mucor sp 1 and 2, and Candida albicans, was studied in this work It was found that the biomasses of the fungus M rouxii IM-80, M rouxii mutant, Mucor sp1, and Mucor sp 2 were very efficient removing the metal in solution, using dithizone, reaching the next percentage of removals: 953%, 887%, 804%, and 783%, respectively The highest adsorption was obtained at pH 55, at 30°C after 24 hours of incubation, with 1 g/100 mL of fungal biomass
57 citations
TL;DR: The results indicate that this zinc(II) complex can intercalate into the stacked base pairs of DNA and compete with the strong intercalator ethidium bromide for the intercalative binding sites.
Abstract: A mononuclear complex of Zn(II), [Zn(DIP)2 (DMP)] (NO3)2·2H2O in which DIP is 4,7-diphenyl-1,10-phenanthroline and DMP is 4,4′-dimethyl-2,2′-bipyridine has been prepared and characterized by 1HNMR spectroscopy, FT-IR, UV-Vis and elemental analysis techniques. DNA-binding properties of the complex were studied using UV-vis spectra, circular dichroism (CD) spectra, fluorescence, cyclic voltammetry (CV), and viscosity measurements. The results indicate that this zinc(II) complex can intercalate into the stacked base pairs of DNA and compete with the strong intercalator ethidium bromide for the intercalative binding sites.
49 citations
TL;DR: Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil and nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge.
Abstract: In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90–100% using a precipitation method with alkaline solution.
45 citations
TL;DR: The metal-binding sites of natural and synthetic dihydroxyindole (DHI) melanins and their respective interactions with Fe(III) ions were measured and interactions in the synthetic system were characterized by infrared spectroscopy by using the characteristic vibrations of catechol and quinone-imine groups.
Abstract: In this work, we measured the metal-binding sites of natural and synthetic dihydroxyindole (DHI) melanins and their respective interactions with Fe(III) ions. Besides the two acid groups detected for the DHI system: catechol (Cat) and quinone-imine (QI), acetate groups were detected in the natural oligomer by potentiometric titrations. At acidic pH values, Fe(III) complexation with synthetic melanin was detected in an Fe(OH)(CatH2Cat) interaction. With an increase of pH, three new interactions occurred: dihydroxide diprotonated catechol, Fe(OH)2(CatH2Cat)−, dihydroxide monoprotonated catechol, [Fe(OH)2(CatHCat)]2−, and an interaction resulting from the association of one quinone-imine and a catechol group, [Fe(OH)2(Qi−)(CatHCat)]3−. In the natural melanin system, we detected the same interactions involving catechol and quinone-imine groups but also the metal interacts with acetate group at pH values lower than 4.0. Furthermore, interactions in the synthetic system were also characterized by infrared spectroscopy by using the characteristic vibrations of catechol and quinone-imine groups. Finally, scanning electronic microscopy (SEM) and energy-dispersive X-ray (EDS) analysis were used to examine the differences in morphology of these two systems in the absence and presence of Fe(III) ions. The mole ratio of metal and donor atoms was obtained by the EDS analysis.
42 citations
TL;DR: Describing a new method to produce nanostructured collagen-apatite composites on titanium alloy substrate, by combining electrospinning and biomimetic mineralization, showed that the obtained mineralized scaffolds have morphological, structural, and chemical compositional features similar to natural bone extracellular matrix.
Abstract: Titanium and its alloys are currently the mainly used materials to manufacture orthopaedic implants due to their excellent mechanical properties and corrosion resistance. Although these materials are bioinert, the improvement of biological properties (e.g., bone implant contact) can be obtained by the application of a material that mimics the bone extracellular matrix. To this aim, this work describes a new method to produce nanostructured collagen-apatite composites on titanium alloy substrate, by combining electrospinning and biomimetic mineralization. The characterization results showed that the obtained mineralized scaffolds have morphological, structural, and chemical compositional features similar to natural bone extracellular matrix. Finally, the topographic distribution of the chemical composition in the mineralized matrix evaluated by Fourier Transform Infrared microspectroscopy demonstrated that the apatite nanocrystals cover the collagen fibers assembled by the electrospinning.
42 citations
TL;DR: It is suggested that a rougher surface which provided calcium and phosphate ions have the ability to enhance the proliferation of osteoblast and the inhibition of fibroblast growth that enhance implant success ratios.
Abstract: The major challenge for dental implants is achieving optimal esthetic appearance and a concept to fulfill this criterion is evaluated. The key to an esthetically pleasing appearance lies in the properly manage the soft tissue profile around dental implants. A novel implant restoration technique on the surface was proposed as a way to augment both soft- and hard-tissue profiles at potential implant sites. Different levels of roughness can be attained by sandblasting and acid etching, and a tetracalcium phosphate was used to supply the ions. In particular, the early stage attaching and repopulating abilities of bone cell osteoblasts (MC3T3-E1), fibroblasts (NIH 3T3), and epithelial cells (XB-2) were evaluated. The results showed that XB-2 cell adhesive qualities of a smooth surface were better than those of the roughened surfaces, the proliferative properties were reversed. The effects of roughness on the characteristics of 3T3 cells were opposite to the result for XB-2 cells. E1 proliferative ability did not differ with any statistical significance. These results suggest that a rougher surface which provided calcium and phosphate ions have the ability to enhance the proliferation of osteoblast and the inhibition of fibroblast growth that enhance implant success ratios.
TL;DR: The detailed thermodynamic characterization of such proteins showed that PpcA and PpcD have an important redox-Bohr effect that might implicate these proteins in the e−/H+ coupling mechanisms to sustain cellular growth.
Abstract: The bacterium Geobacter sulfurreducens (Gs) can grow in the presence of extracellular terminal acceptors, a property that is currently explored to harvest electricity from aquatic sediments and waste organic matter into microbial fuel cells. A family composed of five triheme cytochromes (PpcA-E) was identified in Gs. These cytochromes play a crucial role by bridging the electron transfer from oxidation of cytoplasmic donors to the cell exterior and assisting the reduction of extracellular terminal acceptors. The detailed thermodynamic characterization of such proteins showed that PpcA and PpcD have an important redox-Bohr effect that might implicate these proteins in the e−/H+ coupling mechanisms to sustain cellular growth. The physiological relevance of the redox-Bohr effect in these proteins was studied by determining the fractional contribution of each individual redox-microstate at different pH values. For both proteins, oxidation progresses from a particular protonated microstate to a particular deprotonated one, over specific pH ranges. The preferred e−/H+ transfer pathway established by the selected microstates indicates that both proteins are functionally designed to couple e−/H+ transfer at the physiological pH range for cellular growth.
TL;DR: The TiO2 coating process using anodizing without thermal oxidation gave effective improvement of the osteoconductivity of Ti samples.
Abstract: Various techniques for forming TiO2 coatings on Ti have been investigated for the improvement of the osteoconductivity of Ti implants. However, it is not clear how the oxidizing process affects this osteoconductivity. In this study, TiO2 coatings were prepared using the following three processes: anodizing in 0.1 M H3PO4 or 0.1 M NaOH aqueous solution; thermal oxidation at 673 K for 2 h in air; and a two-step process of anodizing followed by thermal oxidation. The oxide coatings were evaluated using SEM, XRD, and XPS. The water contact angle on the TiO2 coatings was measured as a surface property. The osteoconductivity of these samples was evaluated by measuring the contact ratio of formed hard tissue on the implanted samples (defined as the value) after 14 d implantation in rats' tibias. Anatase was formed by anodizing and rutile by thermal oxidation, but the difference in the TiO2 crystal structure did not influence the osteoconductivity. Anodized TiO2 coatings were hydrophilic, but thermally oxidized TiO2 coatings were less hydrophilic than anodized TiO2 coatings because they lacked in surface OH groups. The TiO2 coating process using anodizing without thermal oxidation gave effective improvement of the osteoconductivity of Ti samples.
TL;DR: This paper focuses on the alkene cleavage catalysed by iron cofactor-dependent enzymes encompassing the reaction mechanisms and the application of these enzymes in biocatalysis.
Abstract: The oxidative cleavage of alkenes is classically performed by chemical methods, although they display several drawbacks. Ozonolysis requires harsh conditions (−78°C, for a safe process) and reducing reagents in a molar amount, whereas the use of poisonous heavy metals such as Cr, Os, or Ru as catalysts is additionally plagued by low yield and selectivity. Conversely, heme and nonheme enzymes can catalyse the oxidative alkene cleavage at ambient temperature and atmospheric pressure in an aqueous buffer, showing excellent chemo- and regioselectivities in certain cases. This paper focuses on the alkene cleavage catalysed by iron cofactor-dependent enzymes encompassing the reaction mechanisms (in case where it is known) and the application of these enzymes in biocatalysis.
TL;DR: The method for investigating metal ion-melanin interactions on solid support is described, and can be used to address biological questions and potentially be applied toward melanin-based water purification.
Abstract: Interactions between metal ions and different forms of melanin play significant roles in melanin biochemistry. The binding properties of natural melanin and related synthetic materials can be exploited for nonbiological applications, potentially including water purification. A method for investigating metal ion-melanin interactions on solid support is described, with lead as the initial target. 2.5 cm discs of the hydrophobic polymer PVDF were coated with synthetic eumelanin from the tyrosinase-catalyzed polymerization of L-dopa, and with melanin extracted from human hair. Lead (Pb2
TL;DR: The DNA binding studies have been investigated by UV-Vis spectroscopy, and the experimental results indicate that these complexes bind to CT DNA with the intrinsic binding constant Kb = 2.5 ± 0.2 × 105 M−1.
Abstract: Mixed ligand complexes of Ni(II) with 1,10-phenanthroline (1,10-Phen) and Schiff bases L1(MIIMP); L2(CMIIMP); L3(EMIIMP); L4(MIIMNP); L5(MEMIIMP); L6(BMIIMP); L7(MMIIMP); L8(MIIBD) have been synthesized. These metal chelates have been characterized by elemental analysis, IR, 1H-NMR, 13C-NMR, Mass, UV-Vis, magnetic moments, and thermogravimetric (TGaDTA) analysis. Spectral data showed that the 1,10-phenanthroline act as neutral bidentate ligand coordinating to the metal ion through two nitrogen donor atoms and Schiff bases acts as monobasic bidentate coordinating through NO donor atoms. All Ni(II) complexes appear to have an octahedral geometry. The antimicrobial activity of mixed ligand complexes has been studied by screening against various microorganisms, it is observed that the activity enhances upon coordination. The DNA binding studies have been investigated by UV-Vis spectroscopy, and the experimental results indicate that these complexes bind to CT DNA with the intrinsic binding constant M−1. MTT is used to test the anticancer effect of the complexes with HL60 tumor cell. The inhibition ratio was accelerated by increasing the dosage, and it had significant positive correlation with the medication dosage.
TL;DR: The experiments indicate that chemical instability and damage to DNA in Pt-DNA samples increase when DNA platination occurs at 37°C for 24 hours, the condition which has been extensively used for in vitro studies.
Abstract: Dry films of platinum chemotherapeutic drugs covalently bound to plasmid DNA (Pt-DNA) represent a useful experimental model to investigate direct effects of radiation on DNA in close proximity to platinum chemotherapeutic agents, a situation of considerable relevance to understand the mechanisms underlying concomitant chemoradiation therapy In the present paper we determine the optimum conditions for preparation of Pt-DNA films for use in irradiation experiments Incubation conditions for DNA platination reactions have a substantial effect on the structure of Pt-DNA in the films The quantity of Pt bound to DNA as a function of incubation time and temperature is measured by inductively coupled plasma mass spectroscopy Our experiments indicate that chemical instability and damage to DNA in Pt-DNA samples increase when DNA platination occurs at 37°C for 24 hours, the condition which has been extensively used for in vitro studies Platination of DNA for the formation of Pt-DNA films is optimal at room temperature for reaction times less than 2 hours By increasing the concentration of Pt compounds relative to DNA and thus accelerating the rate of their mutual binding, it is possible to prepare Pt-DNA samples containing known concentrations of Pt while reducing DNA degradation caused by more lengthy procedures
TL;DR: The results showed that this iron(III) complex can bind to DNA via external and groove binding modes.
Abstract: A novel iron(III) complex [Fe(SF)](ClO4)3.2H2O; in which SF = N,N0-bis{5-[(triphenylphosphonium chloride)-methyl] salicylidene}-o-phenylenediamine) has been synthesized and characterized using different physicochemical methods. The binding of this complex with calf thymus (CT) DNA was investigated by circular dichroism, absorption studies, emission spectroscopy, voltammetric studies, and viscosity measurements. The results showed that this complex can bind to DNA via external and groove binding modes.
TL;DR: Compared to pure gypsum, the osteoblasts cultured on strontium-doped samples showed better proliferation rate and higher alkaline phosphatase activity, depending on Sr concentration, which can predict better in vivo behavior of strontia-doping gypsums compared to pure one.
Abstract: This paper describes some physical, structural, and biological properties of gypsum bioceramics doped with various amounts of strontium ions (0.19–2.23 wt%) and compares these properties with those of a pure gypsum as control. Strontium-doped gypsum (gypsum:Sr) was obtained by mixing calcium sulfate hemihydrate powder and solutions of strontium nitrate followed by washing the specimens with distilled water to remove residual salts. Gypsum was the only phase found in the composition of both pure and gypsum:Sr, meanwhile a shift into lower diffraction angles was observed in the X-ray diffraction patterns of doped specimens. Microstructure of all gypsum specimens consisted of many rod-like small crystals entangled to each other with more elongation and higher thickness in the case of gypsum:Sr. The Sr-doped sample exhibited higher compressive strength and lower solubility than pure gypsum. A continuous release of strontium ions was observed from the gypsum:Sr during soaking it in simulated body fluid for 14 days. Compared to pure gypsum, the osteoblasts cultured on strontium-doped samples showed better proliferation rate and higher alkaline phosphatase activity, depending on Sr concentration. These observations can predict better in vivo behavior of strontium-doped gypsum compared to pure one.
TL;DR: The aim of this study was to evaluate the Cu release characteristics in vitro according to the storage fluid and surface roughness, whereby the highest Cu release was determined for samples with corundum-blasted surfaces stored in cell medium.
Abstract: New developments of antimicrobial implant surfaces doped with copper (Cu) ions may minimize the risk of implant-associated infections. However, experimental evaluation of the Cu release is influenced by various test parameters. The aim of our study was to evaluate the Cu release characteristics in vitro according to the storage fluid and surface roughness. Plasma immersion ion implantation of Cu (Cu-PIII) and pulsed magnetron sputtering process of a titanium copper film (Ti-Cu) were applied to titanium alloy (Ti6Al4V) samples with different surface finishing of the implant material (polished, hydroxyapatite and corundum blasted). The samples were submersed into either double-distilled water, human serum, or cell culture medium. Subsequently, the Cu concentration in the supernatant was measured using atomic absorption spectrometry. The test fluid as well as the surface roughness can alter the Cu release significantly, whereby the highest Cu release was determined for samples with corundum-blasted surfaces stored in cell medium.
TL;DR: The experimental results suggest that the nickel(II) complex binds to DNA by partial intercalation binding mode.
Abstract: A V-shaped ligand Bis(2-benzimidazolymethyl)amine (bba) and its nickel(II) picrate (pic) complex, with composition [Ni(bba)(2)](pic)(2)·3MeOH, have been synthesized and characterized on the basis of elemental analyses, molar conductivities, IR spectra, and UV/vis measurements. In the complex, the Ni(II) ion is six-coordinated with a N(2)O(4) ligand set, resulting in a distorted octahedron coordination geometry. In addition, the DNA-binding properties of the Ni(II) complex have been investigated by electronic absorption, fluorescence, and viscosity measurements. The experimental results suggest that the nickel(II) complex binds to DNA by partial intercalation binding mode.
TL;DR: The antibacterial and antifungal activity's data show that the metal complexes have a promising biological activity comparable with the parent ligand against bacterial and fungal species.
Abstract: N-substituted pyridine hydrazide (pyridine-2-carbonyl chloride and 4-chloro-benzoic acid hydrazide) undergoes hydrazide formation of the iminic carbon nitrogen double bond through its reaction with cobalt(II), nickel(II), and copper(II) metal salts in ethanol which are reported and characterized based on elemental analyses, IR, solid reflectance, magnetic moment, molar conductance, and thermal analysis (TG). From the elemental analyses data, 1 : 2 metal complexes are formed having the general formulae [MCl2(HL)2] · yH2O (where M = Co(II), Ni(II), and Cu(II), y = 1–3). The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied. IR spectra show that ligand is coordinated to the metal ions in a neutral bidentate manner with ON donor sites. The solid complexes have been synthesized and studied by thermogravimetric analysis. All the metal chelates are found to be nonelectrolytes. From the magnetic and solid reflectance spectra, the complexes (cobalt(II), nickel(II), and copper(II)) have octahedral and square planner geometry, respectively. The antibacterial and antifungal activity’s data show that the metal complexes have a promising biological activity comparable with the parent ligand against bacterial and fungal species.
TL;DR: It is concluded that the thioindigo molecule must be trapped in a channel, an observation consistent with previous experimental studies.
Abstract: The interaction of thioindigo and the phyllosilicate clay sepiolite is investigated using density functional theory (DFT) and molecular orbital theory (MO). The best fit to experimental UV/Vis spectra occurs when a single thioindigo molecule attaches via Van der Waals forces to a tetrahedrally coordinated Al(3+) cation with an additional nearby tetrahedrally coordinated Al(3+) also present. The thioindigo molecule distorts from its planar structure, a behavior consistent with a color change. Due to the weak interaction between thioindigo and sepiolite we conclude that the thioindigo molecule must be trapped in a channel, an observation consistent with previous experimental studies. Future computational studies will look at the interaction of indigo with sepiolite.
TL;DR: Two new heterocyclic Schiff bases of 4-amino-5-mercapto-3-H/propyl-1,2,4-triazole and 5-nitrofurfuraldehyde and their cobalt, nickel, copper, and zinc complexes have been synthesized and characterized by elemental analyses, spectral studies, thermal techniques, and magnetic moment measurements.
Abstract: Two new heterocyclic Schiff bases of 4-amino-5-mercapto-3-H/propyl-1,2,4-triazole and 5-nitrofurfuraldehyde [] and their cobalt, nickel, copper, and zinc complexes have been synthesized and characterized by elemental analyses, spectral (UV-Vis, IR, 1H NMR, Fluorescence, and ESR) studies, thermal techniques, and magnetic moment measurements. The heterocyclic Schiff bases act as bidentate ligands and coordinate with metal ions through nitrogen and sulphur of the thiol group. The low molar conductance values in DMF indicate that the metal complexes are nonelectrolytes. The magnetic moments and electronic spectral data suggest octahedral geometry for the Co(II), Ni(II), and Zn(II) complexes and square planar for Cu(II) complexes. Two Gram-positive bacteria (Staphylococcus aureus MTCC 96 and Bacillus subtilis MTCC 121), two Gram-negative bacteria (Escherichia coli MTCC 1652 and Pseudomonas aeruginosa MTCC 741), and one yeast, Candida albicans, were used for the evaluation of antimicrobial activity of the newly synthesized compounds.
TL;DR: It has been found that the Schiff bases with Cu(II) or Co( II) ion forming binuclear complexes on (1 : 1) “metal : ligand” stoichiometry correspond to be nonelectrolytic nature for all prepared complexes.
Abstract: New binuclear Co(II) and Co(II) complexes of ONO tridentate heterocyclic Schiff base derived from 4-aminoantipyrine with salicylaldehyde have been synthesized and characterized on the bases of elemental analysis, UV-Vis., FT-IR, and also by aid of molar conductivity measurements, magnetic measurements, and melting points. It has been found that the Schiff bases with Cu(II) or Co(II) ion forming binuclear complexes on (1 : 1) “metal : ligand” stoichiometry. The molar conductance measurements of the complexes in DMSO correspond to be nonelectrolytic nature for all prepared complexes. Distorted octahedral environment is suggested for metal complexes. A theoretical treatment of the formation of complexes in the gas phase was studied, and this was done by using the HyperChem-6 program for the molecular mechanics and semi-empirical calculations. The free ligand and its complexes have been tested for their antibacterial activities against two types of human pathogenic bacteria: the first type (Staphylococcus aureus) is Gram positive and the second type (Escherichia coli) is Gram negative (by using agar well diffusion method). Finally, it was found that compounds show different activity of inhibition on growth of the bacteria.
TL;DR: Thermodynamic parameters for protonation of 1,4-bis(3-aminopropyl)-piperazine and its metal complexation with some divalent metal ions were determined in aqueous solution at constant ionic strength using a potentiometric technique.
Abstract: Thermodynamic parameters for protonation of 1,4-bis(3-aminopropyl)-piperazine (BAPP) and its metal complexation with some divalent metal ions were determined in aqueous solution at constant ionic strength (0.1 M NaNO3) using a potentiometric technique. The order of –ΔG0 and –ΔH0 was found to obey , in accordance with the Irving-Williams order. The formation equilibria of zinc (II) complexes and the ternary complexes Zn(BAPP)L, where L = amino acid, amides, or DNA constituents), have been investigated. Ternary complexes are formed by a simultaneous mechanism. The concentration distribution of the complexes in solution was evaluated as a function of pH. Stoichiometry and stability constants for the complexes formed are reported and discussed. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameter Δlog K.
TL;DR: It was discovered that doping HA by silicon results in hindering this phase transformation process, and the Si-doped HA does not show phase transition to β-TCP or decomposition after heat treatment even at 900°C.
Abstract: A novel approach for depositing hydroxyapatite (HA) films on titanium substrates by using mechanical alloying (MA) technique has been developed. However, it was shown that one-hour heat treatment at 800°C of such mechanically coated HA layer leads to partial transformation of desired HA phase to beta-tri-calcium phosphate (β-TCP) phase. It appears that the grain boundary and interface defects formed during MA promote this transformation. It was discovered that doping HA by silicon results in hindering this phase transformation process. The Si-doped HA does not show phase transition to β-TCP or decomposition after heat treatment even at 900°C.
TL;DR: The indexes of stability indicate that HSA removed Cu2+ from Aβ(1–16), rapidly, decreased Cu-induced aggregation of A β(1-16), and reduced the toxicity of Aβ (1– 16) + Cu 2+ significantly.
Abstract: The interaction of Cu2+ with the first 16 residues of the Alzheimer's amyliod β peptide, Aβ(1–16), and human serum albumin (HSA) were studied in vitro by isothermal titration calorimetry at pH 7.2 and 310 K in aqueous solution. The solvation parameters recovered from the extended solvation model indicate that HSA is involved in the transport of copper ion. Complexes between Aβ(1–16) and copper ions have been proposed to be an aberrant interaction in the development of Alzheimer's disease, where Cu2+ is involved in Aβ(1–16) aggregation. The indexes of stability indicate that HSA removed Cu2+ from Aβ(1–16), rapidly, decreased Cu-induced aggregation of Aβ(1–16), and reduced the toxicity of Aβ(1–16) + Cu2+ significantly.
TL;DR: The screening results have shown that the organotin(IV) complexes (2-6) have better antibacterial activities and have potential as drugs.
Abstract: Five new organotin(IV) complexes of 2-hydroxyacetophenone-2-methylphenylthiosemicarbazone [H(2)dampt, (1)] with formula [RSnCl(n-1)(dampt)] (where R = Me, n = 2 (2); R = Bu, n = 2 (3); R = Ph, n = 2 (4); R = Me(2), n = 1 (5); R = Ph(2), n = 1 (6)) have been synthesized by direct reaction of H(2)dampt (1) with organotin(IV) chloride(s) in absolute methanol. The ligand (1) and its organotin(IV) complexes (2-6) were characterized by CHN analyses, molar conductivity, UV-Vis, FT-IR, (1)H, (13)C, and (119)Sn NMR spectral studies. H(2)dampt (1) is newly synthesized and has been structurally characterized by X-ray crystallography. Spectroscopic data suggested that H(2)dampt (1) is coordinated to the tin(IV) atom through the thiolate-S, azomethine-N, and phenoxide-O atoms; the coordination number of tin is five. The in vitro antibacterial activity has been evaluated against Staphylococcus aureus, Enterobacter aerogenes, Escherichia coli, and Salmonella typhi. The screening results have shown that the organotin(IV) complexes (2-6) have better antibacterial activities and have potential as drugs. Furthermore, it has been shown that diphenyltin(IV) derivative (6) exhibits significantly better activity than the other organotin(IV) derivatives (2-5).
TL;DR: Two SOD-mimic active dimeric Cu(II) chlorido complexes involving the cosmetologically relevant cytokinin kinetin and its derivative N6-(5-methylfurfuryl)adenine (HL2) have been synthesized and characterized by elemental analysis, infrared, and electronic spectroscopy, ESI+ mass spectrometry, conductivity and temperature dependence of magnetic susceptibility measurements, and thermogravimetric and differential thermal analyses.
Abstract: Two SOD-mimic active dimeric Cu(II) chlorido complexes of the compositions [Cu2(μ-HL1)4Cl2]Cl2 (1) and [Cu2(μ-HL2)2(μ-Cl)2(HL2)2Cl2] · 4H2O (2) involving the cosmetologically relevant cytokinin kinetin (N6-furfuryladenine, HL1) and its derivative N6-(5-methylfurfuryl)adenine (HL2) have been synthesized and characterized by elemental analysis, infrared, and electronic spectroscopy, ESI+ mass spectrometry, conductivity and temperature dependence of magnetic susceptibility measurements, and thermogravimetric (TG) and differential thermal (DTA) analyses. The results of these methods, particularly the temperature dependence of magnetic susceptibility, showed the complexes to be dimeric with a strong antiferromagnetic exchange (J = −290 cm−1 for complex 1 and J = −160 cm−1 for 2). The complexes have been identified as auspicious SOD-mimics, as their antiradical activity evaluated by the in vitro SOD-mimic assay resulted in the IC50 values equal to 8.13 μM (1) and 0.71 μM (2).