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2,6-Bis(benzimidazol-2-yl)pyridine (L) ligand and complexes [M(L)Cl(2)] and [Fe(L)(2)](ClO(4))(2) (M=Zn, Cd, Hg) have been synthesized. The geometries of the [M(L)Cl(2)] complexes were derived from theoretical calculation in DGauss/DFT level (DZVP basis set) on CACHE. The central M(II) ion is penta-coordinated and surrounded by N(3)Cl(2) environment, adopting a distorted trigonal bipyramidal geometry. The ligand is tridentate, via three nitrogen atoms to metal centre and two chloride ions lie on each side of the distorted benzimidazole ring. In the [Fe(L)(2)](ClO(4))(2) complex, the central Fe(II) ion is surrounded by two (3N) units, adopting a octahedral geometry. The elemental analysis, molecular conductivity, FT-Raman, FT-IR (mid-, far-IR), (1)H, and (13)C NMR were reported. The antimicrobial activities of the free ligand, its hydrochloride salt, and the complexes were evaluated using the disk diffusion method in dimethyl sulfoxide (DMSO) as well as the minimal inhibitory concentration (MIC) dilution method, against 10 bacteria and the results compared with that for gentamycin. Antifungal activities were reported for Candida albicans, Kluyveromyces fragilis, Rhodotorula rubra, Debaryomyces hansenii, Hanseniaspora guilliermondii, and the results were referenced against nystatin, ketaconazole, and clotrimazole antifungal agents. In most cases, the compounds tested showed broad-spectrum (Gram positive and Gram negative bacteria) activities that were either more effective than or as potent as the references. The binding of two most biologically effective compounds of zinc and mercury to calf thymus DNA has also been investigated by absorption spectra.
BACKGROUND: Prevention of poxvirus infection is a topic of great current interest. We report inhibition of vaccinia virus in cell culture by porphyrins and phthalocyanines. Most previous work on the inhibition of viruses with tetrapyrroles has involved photodynamic mechanisms. The current study, however, investigates light-independent inhibition activity. METHODS: The Western Reserve (WR) and International Health Department-J (IHD-J) strains of vaccinia virus were used. Virucidal and antiviral activities as well as the cytotoxicity of test compounds were determined. RESULTS: Examples of active compounds include zinc protoporphyrin, copper hematoporphyrin, meso(2,6-dihydroxyphenyl)porphyrin, the sulfonated tetra-1-naphthyl and tetra-1-anthracenylporphyrins, selected sulfonated derivatives of halogenated tetraphenyl porphyrins and the copper chelate of tetrasulfonated phthalocyanine. EC50 values for the most active compounds are as low as 0.05 microg/mL (40 nM). One of the most active compounds was the neutral meso(2,6-dihydroxyphenyl)porphyrin, indicating that the compounds do not have to be negatively charged to be active. CONCLUSIONS: Porphyrins and phthalocyanines have been found to be potent inhibitors of infection by vaccinia virus in cell culture. These tetrapyrroles were found to be active against two different virus strains, and against both enveloped and non-enveloped forms of the virus, indicating that these compounds may be broadly effective in their ability to inhibit poxvirus infection.
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Ultra-small (3.1 nm) multifunctional CdS:Mn/ZnS core-shell semiconductor quantum dots (Qdots), which possess fluorescent, radio-opacity, and paramagnetic properties, have been shown here. To demonstrate in vivo bioimaging capability, a rat was administered endovascularly with Qdots conjugated with a TAT peptide. The labeling efficacy of these Qdots was demonstrated on the basis of the histological analysis of the microtome sliced brain tissue, clearly showing that TAT-conjugated Qdots stained brain blood vessels.
A biomineralization process based on the promotion of precipitating agent by the urea-urease enzymatic system is developed to prepare ZnAl layered double hydroxide materials and the effects of the enzymatic reaction parameters on the structural and textural properties of the materials are investigated on the basis of XRD and EM analysis.
The mammalian amygdaloid complex is densely innervated by zinc-containing neurons. The distribution of the terminals throughout the region has been described, but the origins of these zinc-containing fibers have not. The present work describes the origins of one major component of the zinc-containing innervation of the amygdaloid complex, namely, the component that innervates the corticomedial complex. Selective labeling of zinc-containing axons was accomplished by intracerebral microinfusion of selenium anions (SeO3(2-)), a procedure that produces a ZnSe precipitate in zinc-containing axonal boutons with subsequent retrograde transport to the neurons of origin. After infusions of SeO3(2-) into combinations of cortical, medial, or amygdalohippocampal regions, retrogradely labeled zinc-containing somata were found in all amygdaloid nuclei except for the medial and central nuclei, the bed nucleus of the accessory olfactory tract, the nucleus of the lateral olfactory tract, and the anterior amygdaloid area. Extrinsic zinc-containing projections to the same amygdaloid terminal fields were found to originate from the infralimbic, cingulate, piriform, perirhinal and entorhinal cortices, and from the prosubiculum and CA1. Commissural zinc-containing projections were found to originate from the posterolateral and posteromedial cortical nuclei and from the posterior part of the basomedial nucleus. Zinc-containing neurons have been implicated in the pathophysiology of epilepsy, in cell death after seizure or stroke, and in Alzheimer's disease, all clinical conditions that involve the amygdaloid complex. Identification of the zinc-containing pathways is a prerequisite to the elucidation of zinc's role in these disorders.
Treatment of beef heart cytochrome oxidase with fluorescein mercuric acetate (FMA) was found to specifically displace zinc from the enzyme and inhibit the steady-state activity in a parallel fashion. The native cytochrome oxidase preparation contained 2.3 Cu: 2.0 Fe: 1.1 Zn: 0.9 Mg. Addition of 2 equivalents of FMA inhibited the activity by 50% and displaced 60% of the zinc from the enzyme, but did not affect the copper, iron or magnesium content. The pre-steady-state reduction of cytochrome oxidase by ferrocytochrome c was not affected by the FMA treatment, in contrast to the inhibition of steady state activity. These results suggest a possible structural or functional role for zinc in cytochrome oxidase.
Zinc-65 and cadmium-115 m were used for the investigation of the uptake and the release of zinc and cadmium in fish. It has been found that the uptake of these elements directly from water is relatively low. Zinc and cadmium, consumed by fish in food, are released with the biological half-time 0.25 +/- 0.05 days (94%) and 65 +/- 9 days (6%) for zinc, 0.25 +/- 0.05 days (98.5%) and 36 +/- 6 days (1.5%) for cadmium. The comparison with data obtained for mercury species shows that the cumulation of these elements in fish increases in the order cadmium, zinc, inorganic mercury (II), phenylmercury and methylmercury.
In an effort to search for mechanistically new and more potent agents than conventional drugs that target AT-rich sequences in double-stranded DNA, we have tested multi(Zn(2+)-cyclen) complexes. Indeed, they selectively bound to poly(dT) sequences to melt the A-T hydrogen bonds; only 2.5 microM or 4 microM of the p-tris(Zn(2+)-cyclen) complex were required to completely melt a 50 microM nucleobase of double-stranded poly(dA) x poly(dT) or poly(dA-dT)(2) at 25 degrees C. The region with seven consecutive T's in native DNA (150 bp) was protected from micrococcal nuclease hydrolysis, as revealed by footprinting assays, with IC(50) values of 2 microM for p-bis(Zn(2+)-cyclen) and 0.5 microM for p-tris(Zn(2+)-cyclen). The high affinity to AT-rich sequences of these Zn(2+)-cyclen complexes matches or surpasses those of the conventional AT-binding drugs distamycin A (IC(50)=2 microM) and DAPI (5 microM). Moreover, the p-tris(Zn(2+)-cyclen) complex selectively binds to the TATA box sequence of the SV40 early promoter to inhibit the binding of the TATA binding protein as effectively as distamycin A, with an IC(50) value of 0.4 microM. In vitro transcription of poly(dA) x poly(dT) using Escherichia coli RNA polymerase was effectively inhibited by p-tris(Zn(2+)-cyclen). The [(3)H]-ATP incorporation into RNA was more strongly blocked (IC(50)=0.8 microM) than the [(3)H]-UTP incorporation (IC(50)=40 microM), a fact indicating that the p-tris(Zn(2+)-cyclen) complex interacts only with the poly(dT) strand in the double-stranded DNA template.
An electrochemical immunoassay protocol for the simultaneous measurements of proteins, based on the use of different inorganic nanocrystal tracers is described. The multiprotein electrical detection capability is coupled to the amplification feature of electrochemical stripping transduction (to yield fmol detection limits) and with an efficient magnetic separation (to minimize nonspecific adsorption effects). The multianalyte electrical sandwich immunoassay involves a dual binding event, based on antibodies linked to the nanocrystal tags and magnetic beads. Carbamate linkage is used for conjugating the hydroxyl-terminated nanocrystals with the secondary antibodies. Each biorecognition event yields a distinct voltammetric peak, whose position and size reflects the identity and level, respectively, of the corresponding antigen. The concept is demonstrated for a simultaneous immunoassay of beta(2)-microglobulin, IgG, bovine serum albumin, and C-reactive protein in connection with ZnS, CdS, PbS, and CuS colloidal crystals, respectively. These nanocrystal labels exhibit similar sensitivity. Such electrochemical coding could be readily multiplexed and scaled up in multiwell microtiter plates to allow simultaneous parallel detection of numerous proteins or samples and is expected to open new opportunities for protein diagnostics and biosecurity.
The title compound, [ZnCl(2)(C(5)H(9)NO(2))(2)], crystallizes in the centrosymmetric space group C2/c with the Zn atom on a twofold axis. The two proline residues in any one complex thus have the same absolute configuration. Hydrogen bonding links the molecules into linear chains, which run in the crystallographic b direction. The proline residues within any one chain also have an identical absolute configuration.
The two title complexes, [ZnCl2(C11H15N3O3)], (I), and [ZnCl2(C11H15N3O3)].0.5H2O, (II), are mononuclear zinc(II) compounds. In both structures, the Zn(II) atom is four-coordinated in a tetrahedral configuration by one imine N atom and one phenolate O atom of a Schiff base, and by two Cl atoms. The structure of each of the two zinc(II) complex molecules of (II) is similar to that of (I). In (I), the molecules are linked through intermolecular hydrogen bonds, forming a three-dimensional framework. In (II), the solvent water molecules are linked to the zinc(II) moieties through intermolecular O-H...O and O-H...Cl hydrogen bonds. The molecules in (II) are further linked via other intermolecular hydrogen bonds, forming a three-dimensional framework.
There is considerable evidence that ultraviolet radiation (UV) from sunlight is implicated in skin carcinogenesis. So the risks of cutaneous cancer have increased during the last decade due to increase of sun exposure. For a long time, ultraviolet B radiation (UVB: 290-320 nm) have been considered to be the more efficient wavelength in eliciting carcinogenesis in human skin. It is today clear that UVA (320-400 nm), especially UVA1 (340-400 nm) also participate to photo carcinogenesis. One of molecular mechanisms in the biological effects of UV is the induction of reactive oxygen species (ROS) directly or through endogenous photosensitization reactions. UVA radiation mainly acts via this production of ROS and the subsequent oxidative stress seems to play a crucial role in the deleterious effects of UVA. Fortunately, the skin possesses a wide range of interlinked antioxidant defence mechanism to protect itself from damage by UV-induced ROS. However, the capacity of these systems is not unlimited; they can be overwhelmed by excessive exposure to UV and then ROS can reach damaging levels. An interesting strategy to provide photoprotection would be to support or enhance one or more of these endogenous systems. In our experiments, we have evaluated the protective effect of glutathion, selenium and zinc, three compounds playing a pivotal role in the cellular defence against oxidative damage. We have irradiated both by UVA1 and UVB culture of human normal skin fibroblasts or of spontaneously immortalised human keratinocyte cell line Hacat. Before irradiation, treated cells were submitted to zinc deprivation by a diffusible zinc chelator, NNN' N'-tetrakis (2-pyridylmethyl) ethylene diamine (TPEN) or supplied with zinc chloride, thiols (N-acetyl-cysteine; N-acetyl-homocysteine-thiolactone, L2oxothiozolidine-4 carboxylate) selenium as sodium selenite. The cell viability was measured using the adhesion-proliferation method or a tetrazolium colorimetric assay. The damages induced to cellular membrane were appreciated by determination of thiobarbituric reactants (Tbars) by a fluorometric micromethod. Cellular DNA damage was examined by strand break determination carried out using the method described by Birnboim and Jevcak and by the Comet assay. Our results show that: UVA1 have a main part in cytotoxic effect of UVA and this effect is linked to ROS; thiols and selenium protect cells against UVA radiation with a synergic interaction and this protection acts though an increase in glutathion peroxidase activity; zinc protects against cytotoxicity of UVA and UVB and against UVB induced DNA damages; above all, DNA damages induced by UVA or UVB are significantly prevented by thiol molecules, selenium and zinc. As DNA damages have a main place in photocarcinogenesis, our results point out the potential interest of a photoprotection based on the support of endogenous antioxidant system. The research of new ways for photoprotection is indeed a necessity because sunscreens did not give convincing evidences of efficacy in preventing skin cancers.
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