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At least 1,063 records · Page 59Linked to original sources
PubMed2006

Synthesis, characterization and in vitro antibacterial activity of new steroidal thiazolo quinoxalines.

Herein, we report the synthesis of different steroidal thiazolo quinoxaline derivatives as antibacterial agents against Escherichia coli. Steroidal ketone thiosemicarbazones (4-6) were obtained from corresponding ketones (1-3) by refluxing with thiosemicarbazide. The thiosemicarbazones on reaction with 2,3-dichloroquinoxalines at 80 degrees C gives 3beta-acetoxy-5alpha-cholestan-6-[thiazolo(4,5-b)quinoxaline-2-yl-hydrazone] (7), 3beta-chloro-cholestan-6-[thiazolo(4,5-b)quinoxaline-2-yl-hydrazone] (8), and 5alpha-cholestan-6-[thiazolo(4,5-b)quinoxaline-2-yl-hydrazone] (9). The structures of the compounds were evident by elemental, IR, (1)H NMR and FAB mass spectral analyses. The antibacterial activities of these compounds were evaluated by disk diffusion method against the culture of E. coli and the results were compared with the standard drug amoxicillin. The results reveal that the compounds are better antibacterial agents as compared to amoxicillin. Among all the three compounds (7-9), compound 8 showed better zone of inhibition.

Anti-Bacterial Agents↗
PubMed2005

Spectral and magnetic studies on manganese(II), cobalt(II) and nickel(II) complexes with Schiff bases.

Mn(II), Co(II) and Ni(II) complexes of 2-methylcyclohexanone thiosemicarbazone(MCHTSC L(1)) and 2-methylcyclohexanone-(4)N-methyl-3-thiosemicarbazone (MCHMTSC L(2)), general composition [M(L)(2)X(2)] (where M = Mn(II), Co(II), Ni(II), L = L(1) or L(2) and X = Cl(-), NO(3)(-), and [(1/2)SO(4)(2-)) have been synthesized and characterized by elemental analysis, magnetic susceptibility measurements, UV-vis, IR, EPR, and mass spectral studies. Various physico-chemical techniques suggest an octahedral geometry for all the complexes.

Cations, Divalent↗
PubMed2001

Towards new transition metal-based hypoxic selective agents for therapy and imaging.

The greater lability of Co(II) relative to Co(III) can potentially be used to achieve selective delivery of nitrogen mustard type molecules to hypoxic cells. Attempts to improve the stability of the Co(II) state by utilising tripodal tetradentate ligands are described, together with the results of DF calculations. Rhenium has two beta-emitting isotopes (186)Re and (188)Re that have potential for use to treat cancer if the complexes can be targeted with sufficient specificity. We describe some new rapid low temperature routes using hydrazines to labile Re(V) and Re(III) species which provide potential convenient access to a wide range of oxo- and diazenido-complexes. The synthesis of new Re(V) and Re(III) thiosemicarbazone complexes is presented in the context of obtaining hypoxic selective species. Copper(II) bis(thiosemicarbazone) complexes are known to be hypoxic selective and spectroscopic, cyclic voltammetric and computational studies of the mechanism are presented, together with the synthesis of new Cu(II) complexes directed towards the hypoxic selective delivery of nitrogen mustard type molecules.

Antineoplastic Agents, Alkylating↗
PubMed2003

Synthesis of some new 2,4-disubstituted thiazoles as possible antibacterial and anti-inflammatory agents.

A series of arylthioureas (1), aromatic aldehyde thiosemicarbazones (2) and 5-aryl-2-furfuraldehyde thiosemicarbazones (3) were condensed with 2,4-dichloro-5-fluorophenacyl bromide to yield respective arylaminothiazoles, arylidene/5-aryl-2-furfurylidene hydrazinothiazoles (4). The newly synthesized compounds were characterized by IR, 1H-NMR and mass spectral studies. These compounds were also screened for their antibacterial and anti-inflammatory activities. Two of the newly synthesized compounds showed anti-inflammatory activity comparable with that of Ibuprofen.

Animals↗
PubMed2005

Controlled ligand deprotonation in lanthanide chelates with asymmetric semicarbazone/benzoylhydrazone or semicarbazone/thiosemicarbazone coordination spheres.

Asymmetric, potentially pentadentate ligands (H(2)L(3)) are formed by subsequent condensation of a semicarbazide and benzoylhydrazine on 2,6-diacetylpyridine. Two equivalents of H(2)L(3) reacts with CeCl(3).7H(2)O, Ce(SO(4))(2).4H(2)O, or EuCl(3).6H(2)O under formation of [Ln(III)(HL(3))(2)](+) cations (Ln = Ce, Eu) with exclusive deprotonation of the benzoylhydrazone ligand arms. The Ce(4+) ion of the sulfate salt is reduced during the reaction and forms 10-coordinate singly charged complex cations, the structure of which is identical to the product of the reaction of cerium(III) chloride. The exact position of deprotonation in the ligands is resolved by infrared spectroscopy, bond lengths considerations, and the hydrogen bonding in the solid-state structures of the products. A similar approach allows the synthesis of mixed semicarbazone/thiosemicarbazone ligands (H(2)L(4)). The reaction of H(2)L(4) with Sm(NO(3))(3).6H(2)O leads to the first structurally characterized lanthanide complex with thiosemicarbazone coordination. The solid-state structure of the 10-coordinate complex [Sm(HL(4))(2)]NO(3).H(2)O shows exclusive deprotonation of the thiosemicarbazone arms of the ligands. All isolated complexes are air stable and do not undergo ligand exchange reactions or hydrolysis in the presence of water.

Journal Article↗
PubMed2006

Synthesis and characterization of new trimeric rhenium(I) complexes. The influence of steric factors on the size of pyrazolonaterhenium(I) metallomacrocycles.

The reaction of [ReX(CO)5] with thiosemicarbazones H2L(R) derived from beta-keto esters (X = Cl, Br; R = Me, Ph) allowed the isolation of cyclic trimeric complexes [Re3(pyz(R))3(CO)9], where pyz(R) is the pyrazolonate corresponding to the thiosemicarbazone. Electron spray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) monitoring of the reactions of H2L(Ph) in toluene confirmed that the trimer was formed in the reaction mixture and no higher oligomer was detected. These studies, together with the X-ray structures of the trimeric complexes, afford new insight into the factors influencing the self-assembly of pyrazolonaterhenium(I) complexes.

Crystallography, X-Ray↗
PubMed1999

Design, Synthesis, and Crystal Structure of a cis-Configuration N(2)S(2)-Coordinated Palladium(II) Complex: Role of the Intra- and Intermolecular Aromatic-Ring Stacking Interaction.

A cis-configuration bis(4,5-diazafluorene-9-one thiosemicarbazone) palladium trihydrate, which exhibits approximately five times SHG (second harmonic generation) efficiency of urea, has been designed, synthesized, and structurally characterized. The complex, C(24)H(16)N(10)PdS(2).3H(2)O, crystallizes in trigonal space group P3(1) with cell parameters a = 10.749(2) Å, c = 19.872(4) Å, V = 1988.3(6) Å(3), and Z = 3. The coordination geometry about the Pd(II) is surprisingly a cis-configuration square-planar formed by two imino nitrogen atoms N(3) and N(8) and two sulfur atoms S(1) and S(2) from two thiosemicarbazone ligands. Intramolecular contact analyses in the crystals and 1D and 2D (1)H NMR spectra in solution show that the cis-positioning of the two ligands was stabilized by the pi-pi interaction between the two delocalized diazafluorene moieties. Detailed crystal structure analyses demonstrate that both the intermolecular pi-pi stacking between the diazafluorene planes in different molecules and intermolecular hydrogen bonds between the water molecules and the deprotonated ligands might be the factors that influence the molecules to be packed in the acentric space group P3(1). The crystal structure of the free ligand was also reported here for comparison. The ligand, C(12)H(9)N(5)S, crystallizes in orthorhombic space group Pbca with cell parameters a = 8.432(2) Å, b = 15.427(3) Å, c = 17.387(3) Å, V = 2272.7(8) Å(3), and Z= 8. The thiosemaicarbazone moiety adopts an E configuration with N(1) cis to N(3).

Journal Article↗
PubMed1983

Antitrichomonal activity of compounds that affect DNA and its repair.

The trichomonacidal activity of dimethyl sulphate (DMS) was increased a 100-fold by administration in combination with benzamide and aminobenzamides, compounds thought to interfere with DNA repair in mammalian cells. The same benzamides did not enhance the trichomonacidal activities of metronidazole or a thiosemicarbazone. The results suggest that Trichomonas vaginalis is able to repair damaged DNA and that neither metronidazole nor the thiosemicarbazone affect trichomonal DNA in the same way as DMS. They do not rule out the possibility that the drugs have some other action on DNA.

Animals↗
PubMed1968

In vivo antiviral properties of biologically active compounds. II. Studies with influenza and vaccinia viruses.

The in vivo anti-influenza virus and antivaccinia virus activity of 156 biologically active compounds was determined. One of two criteria was used for evaluating activity against the influenza virus. The criteria were increase in survivor number and mean survival time, and reduction in virus-induced lung consolidation in treated, infected Swiss mice. Increase in survivor number and mean survival time were the criteria for evaluation of antivaccinia virus activity. Several drug doses were tested against two virus concentrations to demonstrate antiviral activity more clearly. Two compounds were considered significantly active against the influenza virus: DL-noformicin (NSC 72942) and amantadine hydrochloride (NSC 83653). Eleven compounds had reproducible activity against vaccinia virus: isatin-beta-thiosemicarbazone (NSC 721), 6-azauracil (NSC 3425), 9-alpha-fluoro-2alpha-methylhydrocortisone 21-acetate (NSC 12601), 5-[bis(2-chloroethyl)amino]uracil (NSC 34462), 5-iodo-2'-deoxyuridine (NSC 39661), streptonigrin (NSC 45383), N-methylisatin beta-thiosemicarbazone (NSC 69811), cytovirin (NSC 91770), 9-beta-D-arabinofuranosyladenine (NSC 404241), and 5-(mercaptomethyl)uracil (NSC 529351).

Alkylating Agents↗
PubMed1985

Characterization of a temperature-sensitive mutant of vaccinia virus reveals a novel function that prevents virus-induced breakdown of RNA.

We have attempted to characterize the molecular defect in a temperature-sensitive mutant of vaccinia virus, ts22, which has an abortive late phenotype. At the nonpermissive temperature, ts22 displays normal viral protein synthesis until 8 h postinfection. Between 8 and 10 h after infection all viral protein synthesis ceases abruptly. Characterization of ts22 revealed that (i) primary transcription of late viral genes was not grossly impaired, (ii) late viral mRNA was biologically inactive since it could not stimulate in vitro protein synthesis, and (iii) extensive cleavage of rRNA and late viral mRNA occurred at the time that viral protein synthesis aborted in vivo. These data suggest that ts22 is defective in a function which prevents host rRNA and viral mRNA from being degraded. Inhibitor studies with cytosine arabinoside and cycloheximide showed that induction of and protection from rRNA breakdown occurred at approximately the same time during infection and required late viral gene expression. The viral protein synthesis pattern observed in vaccinia virus-infected cells treated with the drug isatin-beta-thiosemicarbazone was strikingly similar to that observed in ts22-infected cells at the nonpermissive temperature (J. Cooper, B. Moss, and E. Katz, Virology 96:381-392, 1979). Analysis of rRNA integrity in isatin-beta-thiosemicarbazone-treated, vaccinia virus-infected cells revealed extensive cleavage of rRNA, suggesting that the ts22 and drug inhibitor may function in the same pathway.

DNA, Viral↗
PubMed1989

Modulation of ppp(A2'p)nA-dependent RNase by a temperature-sensitive mutant of vaccinia virus.

Activation of the ppp(A2'p)nA (2-5A)-dependent RNase was investigated during the abortive infection of BSC40 cells by a temperature-sensitive mutant of vaccinia virus, ts22. At the nonpermissive temperature, ts22 has an abortive late phenotype. At the onset of late-viral-gene expression, viral mRNA is degraded and rRNA is cleaved into discrete fragments in the absence of prior interferon treatment (R. F. Pacha and R. C. Condit, J. Virol. 56:395-403, 1985). Concomitant with rRNA cleavage, an increase in 2-5A occurred late during infection. Discrete 18S- and 28S-rRNA degradation products from BSC40 cells infected with ts22 at the nonpermissive temperature comigrated in denaturing agarose gels with rRNA cleaved fragments produced by the activation of 2-5A-dependent RNase in uninfected cells transfected with exogenous 2-5A. An increase in 2-5A levels and a similar discrete and characteristic degradation of rRNA were observed in BSC40 cells infected with wild-type vaccinia virus in the presence of isatin-beta-thiosemicarbazone. The results show that the ts22 lesion and the action of isatin-beta-thiosemicarbazone may affect the same pathway, leading to the activation of latent 2-5A-dependent RNase and resulting in indiscriminate RNA degradation and inhibition of viral replication.

Adenine Nucleotides↗
PubMedDate not supplied

Ribonucleotide reductase: an important enzyme in the replication of herpes simplex virus type 1 and a target for antiviral chemotherapy.

Herpes simplex virus encodes a ribonucleotide reductase that catalyzes the formation of deoxyribonucleotides from ribonucleotides. The enzyme is not essential for either viral DNA synthesis or replication, yet inhibitors of this enzyme suppress viral replication. To clarify the role of the ribonucleotide reductase in virus infection and to evaluate it as an antiviral target, the metabolism of deoxyribonucleotides in infected cells was examined. Our results show that the cellular ribonucleotide reductase is incapable of generating adequate deoxyribonucleoside triphosphate pools to support efficient virus replication. Additionally, we have shown that the virus is unable to efficiently utilize salvaged deoxyribonucleosides from degraded cellular DNA. A selective inhibitor of the viral ribonucleotide reductase, 2-acetylpyridine thiosemicarbazone, decreased deoxyribonucleotide pools in infected cells, thus inhibiting viral DNA synthesis. This compound also inhibited the cellular ribonucleotide reductase to some extent, thereby enhancing its antiviral activity. The antiviral effects of acyclovir were potentiated by 2-acetylpyridine thiosemicarbazone in the wild-type virus but not in the ribonucleotide reductase mutant, ICP6 delta. Collectively, these data strongly suggest that the viral ribonucleotide reductase is an important enzyme in viral replication and a valid target for antiviral chemotherapy.

Acyclovir↗
PubMed2003

Synthesis and biological activities of 2,6-diaryl-3-methyl-4-piperidone derivatives.

In the present study, a new series of 2,6-diaryl-3-methyl-4-piperidones was synthesized by Mannich reaction (condensation) of ethyl-methyl ketone, substituted aromatic aldehydes and ammonium acetate. Oximes and thiosemicarbazone derivatives of 2,6-diaryl-3-methyl-4-piperidones were synthesized by reaction with hydroxylamine hydrochloride and thiosemicarbazide respectively. The chemical structures were confirmed by means of IR, 1H-, 13C-NMR and mass spectral data. The compounds were screened for acute toxicity, analgesic, local anaesthetic and antifungal activity. 2-(4-Methylphenyl)-3-methyl-6-(4-chlorophenyl)-piperidin-4-one 2 exhibited the highest analgesic and local anaesthetic activity. The oximes and thiosemicarbazones were completely devoid of analgesic and local anaesthetic activity. 2-(4-Methylphenyl)-3-methyl-6-(4-hydroxyphenyl)-piperidin-4-oxime 21 and 2-(4-methoxyphenyl)-3-methyl-6-(4-chlorophenyl)-piperidin-4-oxime 17 exhibited potent antifungal activity against Aspergillus niger. Antifungal activity against Candida albicans was observed only with 2-(4-dimethylaminophenyl)-3-methyl-6-(4-chlorophenyl)-piperidin-4-oxime 20. 2,6-Diaryl-3-methyl-4-piperidones did not exhibit antifungal property.

Analgesics↗
PubMed1992

A novel intermediate in the interaction of thiosemicarbazide with sheep liver serine hydroxymethyltransferase.

An unusual intermediate bound to the enzyme was detected in the interaction of thiosemicarbazide with sheep liver serine hydroxymethyltransferase. This intermediate had absorbance maxima at 464 and 440 nm. Such spectra are characteristic of resonance stabilized intermediates detected in the interaction of substrates and quasi-substrates with pyridoxal phosphate enzymes. An intermediate of this kind has not been detected in the interaction of thiosemicarbazide with other pyridoxal phosphate enzymes. This intermediate was generated slowly (t 1/2 = 4 min) following the addition of thiosemicarbazide (200 microM) to sheep liver serine hydroxymethyltransferase (5 microM). It was bound to the enzyme as evidenced by circular dichroic bands at 464 and 440 nm and the inability to be removed upon Centricon filtration. The kinetics of interaction revealed that thiosemicarbazide was a slow binding reversible inhibitor in this phase with a k(on) of 11 M-1 s-1 and a k(off) of 5 x 10(-4) s-1. The intermediate was converted very slowly (k = 4 x 10(-5) s-1) to the final products, namely the apoenzyme and the thiosemicarbazone of pyridoxal phosphate. A minimal kinetic mechanism involving the initial conversion to the intermediate absorbing at longer wavelengths and the conversion of this intermediate to the final product, as well as, the formation of pyridoxal phosphate-thiosemicarbazone directly by an alternate pathway is proposed.

Animals↗
PubMed2002

Therapeutic potential of iron chelators in cancer therapy.

The success of DFO at markedly inhibiting the growth of aggressive tumors such as neuroblastoma and leukemia justifies interest in the development of chelators as anti-neoplastic agents. This is emphasized by the fact that DFO has suboptimal properties, namely poor membrane permeability and a very short serum half-life. More recently, the thiosemicarbazone chelator, Triapine, has entered a phase I clinical trial again confirming the potential of these compounds. Further studies examining the effects of chelators on neoplastic cells will not only be valuable in terms of identifing novel anti-cancer agents, but will also provide new information on the role of Fe in cell cycle control.

Animals↗
PubMed1994

Binding of carbohydrates to solid supports, Part 2: Reaction of sugar hydrazones with isothiocyanate-substituted polystyrene.

The binding of sugars to a polymer support as thiosemicarbazones has been investigated as a means of immobilizing glycans. Hydrazones of glucose and N-acetylglucosamine were prepared by reaction with hydrazine hydrate, and successfully reacted with isothiocyanate-substituted polystyrene by incubation at room temperature and neutral pH. The binding was efficient and stable in aqueous buffers over a range of pH conditions. The bound sugars were recovered in moderate yield by treatment of the beads with hydrazine hydrate, benzaldehyde or acetone. Direct binding of reducing sugars to thiosemicarbazide-substituted polystyrene was not successful because of the unfavourable thermodynamics.

Binding Sites↗
PubMed1991

Novel broad-spectrum metal-based antifungal agents. Correlations amongst the structural and biological properties of copper (II) 2-acetylpyridine N4-dialkylthiosemicarbazones.

Copper(II) complexes of the type [Cu(L)X], where L = tridentate anion of 2-acetylpyridine N4-diethyl thiosemicarbazone and X = C1 or Br, were screened against seven fungal strains pathogenic to man viz. Aspergillus niger, Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans, Tricophyton rubrum, Epidermophyton floccosum and Microsporum canis. The greater growth inhibition exhibited by the bromo complex can be explained on the basis of its lower Cu(II)/Cu(I) redox couple and greater covalent bonding. These compounds represent a novel class of metal-based antifungal agents which provide opportunities for a large number of synthetic variations for modulation of the activities.

Antifungal Agents↗