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PubMed2004

Synthesis, characterization and in vitro anti-amoebic activity of new palladium(II) complexes with 5-nitrothiophene-2-carboxaldehyde N(4)-substituted thiosemicarbazones.

Reaction between [Pd(DMSO)(2)Cl(2)] (DMSO=dimethylsulfoxide) and N(4)-substituted thiosemicarbazones derived from 5-nitrothiophene-2-carboxaldehyde (L) afforded the complexes [Pd(L)Cl(2)]. These new complexes have been characterized by elemental analyses and spectroscopic studies. Spectroscopic studies reveal that thionic sulfur and azomethine nitrogen atom of thiosemicarbazones are coordinated to metal ion. The testing of the anti-amoebic activity of these complexes against the protozoan parasite Entamoeba histolytica suggests that compound 9, 10, and 11 might be endowed with important anti-amoebic properties since they showed less IC(50) values than metronidazole. Moreover, compound 11 displays notable amoebicidal activity than metronidazole (IC(50) values of 0.79 microM vs 1.93 microM, respectively).

Aldehydes↗
PubMed2005

Discovery of potent thiosemicarbazone inhibitors of rhodesain and cruzain.

Herein we report the synthesis and evaluation of a series of thiosemicarbazones as potential inhibitors of cysteine proteases relevant to parasitic diseases. Derivatives of thiosemicarbazone 1 were discovered to be potent inhibitors of cruzain and rhodesain, crucial proteases in the life cycles of Trypanosoma cruzi and T. brucei rhodesiense, the organisms causing Chagas' disease and sleeping sickness. However, the entire series had only modest potency against falcipain-2, an essential protease for Plasmodium falciparum, the organism causing malaria. Among the active inhibitors, several potently inhibited proliferation of cultures of T. brucei. However, only modest activity was observed in inhibition of proliferation of T. cruzi or P. falciparum.

Cysteine Endopeptidases↗
PubMed2005

Synthesis of thiosemicarbazone and 4-thiazolidinone derivatives and their in vitro anti-Toxoplasma gondii activity.

Thiosemicarbazone and 4-thiazolidinone derivatives were synthesized in one and two step, respectively, from thiosemicarbazide, in satisfactory yields. Then, the synthesized compounds were submitted to evaluation against host cells infected with Toxoplasma gondii. The present studies showed that thiosemicarbazones 2 and 4-thiazolidinone derivatives 3 were effective against intracellular T. gondii.

Animals↗
PubMed2005

Copper(II) complexes with substituted thiosemicarbazones of thiophene-2-carboxaldehyde: synthesis, characterization and antiamoebic activity against E. histolytica.

In an effort to develop potent antiamoebic agents, a series of thiosemicarbazone (TSC) ligands 1-5 derived from thiophene-2-carboxaldehyde and N4-substituted thiosemicarbazides has been prepared and characterized using various spectroscopic techniques. Treatment of the ligands with cupric chloride produced the copper(II) complexes [Cu(TSC)2Cl2] 1a-5a where ligand bind through thionic sulfur and the azomethine nitrogen. The possible geometries of the complexes were assigned on the basis of magnetic moment, electronic and thermal patterns as well as infrared spectral studies. The thiosemicarbazones and their copper complexes were tested for their in vitro antiamoebic activity against HK-9 strain of Entamoeba histolytica and showed significant growth inhibition. The results revealed that these complexes are effective chemicals in inhibiting amoebal growth, with compound 5 (having -N(CH3)(C6H5) substituent at N4) and complexes 1a-5a being more effective than the commercial antiamoebic drug, metronidazole, based on IC50 values. These data also indicated that the compounds 3a and 5a are most effective among the complexes studied (IC50=0.26 microM of 3a and IC50=0.21 microM of 5a versus IC50=1.81 microM of metronidazole).

Aldehydes↗
PubMed2006

Synthesis, characterisation and cytotoxic properties of the N1,N4-diarylidene-S-methyl-thiosemicarbazone chelates with Fe(III) and Ni(II).

Reactions of 2-hydroxy-3-methoxy, 2-hydroxy-4-methoxy-benzaldehyde with 3- and 4-methoxy-substituted salicylaldehyde S-methyl-thiosemicarbazones in the presence of FeCl(3) and NiCl(2) resulted in the corresponding methoxy-substituted N(1),N(4)-diarylidene-S-methyl-thiosemicarbazone chelates. Characterisation of the compounds in the [Fe(L)Cl] and [Ni(L)] general formula was accomplished by means of elemental analysis, conductivity and magnetic measurements, (1)H NMR, UV-vis, IR and mass spectroscopy. Cytotoxicity and proliferation experiments using K562 chronic myeloid leukemia cell line and ECV 304 human endothelial cell line imply that the iron(III) chelates may have anti-leukemic effects with 3.5 microg/dl LD(50) dose.

Antineoplastic Agents↗
PubMed2004

Synthesis, characterization and biological activity of copper complexes with pyridoxal thiosemicarbazone derivatives. X-ray crystal structure of three dimeric complexes.

A dimeric copper complex of the unsubstituted pyridoxal thiosemicarbazone (H(2)L), [[Cu(HL)(OH(2))](2)]Cl(2).2H(2)O, previously tested on Friend murine cell lines has been recently resynthesized to evaluate its behavior on different murine and human leukemic cell lines and has been compared, in vitro and in vivo, with its monomeric counterpart [Cu(H(2)L)(OH(2))Cl]Cl. On TS/A murine adenocarcinoma cell line in vitro, both compounds significantly inhibit cell proliferation at micromolar concentrations, although the dimeric compound is more active. Despite this cytotoxicity they lack in vivo activity on TLX5 lymphoma. The unsubstituted dimeric [[Cu(HL)(OH(2))](2)]Cl(2).2H(2)O induces apoptosis on CEM and U937 human cell lines, with IC(50) concentrations of 1.2 x 10(-5) and 6.7 x 10(-6) M, respectively, but it is inactive on K562. Moreover, it alters significantly the cell cycle of U937 and CEM lines and decreases the telomerase activity of U937. To verify if other dimeric copper complexes show relevant biological activity new complexes with N-substituted pyridoxal thiosemicarbazones have been synthesized and characterized using spectroscopic techniques. Three of them, namely [Cu(Me(2)-HL)Cl](2).6H(2)O (Me(2)-H(2)L=pyridoxal N1,N1-dimethylthiosemicarbazone) (1), [Cu(MeMe-HL)Cl](2)Cl(2).4H(2)O (MeMe-HL=pyridoxal N1,N2-dimethylthiosemicarbazone) (2), [Cu(Et-H(2)L)Cl](2)Cl(2).2H(2)O (Et-H(2)L=pyridoxal N1-ethylthiosemicarbazone) (3), were also characterized by X-ray diffractometry. These complexes are dimeric and all three present a square pyramidal coordinative geometry with the ligand showing an SNO tridentate behavior. Their biological activities have been tested in vitro on U937, CEM and K562 cell lines to ascertain their effectiveness in comparison to the corresponding unsubstituted complex [[Cu(HL)(OH(2))](2)]Cl(2).2H(2)O. Compound 1 shows weak proliferation inhibition on all three cell lines, but it does not induce apoptosis and it does not inhibit telomerase activity, compound 2 is not effective at low concentration and is toxic at higher doses; compound 3 inhibits CEM cell growth better than complex 1 but it does not exert any other biological effect.

Adenocarcinoma↗
PubMed2004

Palladium(II) complexes of 2-benzoylpyridine-derived thiosemicarbazones: spectral characterization, structural studies and cytotoxic activity.

Palladium(II) complexes of 2-benzoylpyridine thiosemicarbazone (H2Bz4DH) and its N4-methyl (H2Bz4M) and N4-phenyl (H2Bz4Ph) derivatives were obtained and fully characterized. [Pd(2Bz4DH)Cl] (1) crystallizes in the monoclinic space group P21/c with a=11.671(1), b=10.405(1), c=13.124(1), beta=115.60(1) degrees and Z=4; [Pd(2Bz4M)Cl] (2) in the monoclinic space group P21/c with a=9.695(1), b=15.044(1), c=10.718(1) A, beta=105.38(1) degrees and Z=4 and [Pd(2Bz4Ph)Cl] (3) in the triclinic space group P1 with a=9.389(1), b=13.629(1), c=15.218(1) A, alpha=70.25(1), beta=73.46(1), gamma=83.57(1) degrees and two independent molecules per asymmetric unit (Z=4). All complexes show a quite similar planar fourfold environment around palladium(II). A negatively charged organic molecule acts as a tridentate ligand and binds to the metal through the pyridine nitrogen, the imine nitrogen and the sulfur atom. A chloride ion occupies the fourth coordination site. The planar complexes stack nearly parallel to one another in the lattice conforming a layered crystal structure. The cytotoxic activity of the thiosemicarbazones and their metal complexes was tested against the MCF-7, TK-10 and UACC-62 human tumor cell lines. The ligands exhibit lower values of GI50 and LC50 than the complexes, H2Bz4Ph being the most active with GI50<0.003 microM; LC50=13.4 microM; GI50=9.3 microM, LC50=12.9 microM; GI50<0.003, LC50=13.8 microM in the MCF-7, TK-10 and UACC-62 cell lines, respectively. Among the complexes, [Pd(2Bz4Ph)Cl] (3) exhibited the lowest values of GI50 in the three studied cell lines.

Antineoplastic Agents↗
PubMed2005

Nickel (II) complexes of naphthaquinone thiosemicarbazone and semicarbazone: synthesis, structure, spectroscopy, and biological activity.

Ni(II) complexes of ortho-naphthaquinone thiosemicarbazone and semicarbazone were synthesized and spectroscopically characterized. The X-ray crystal structure of both the complexes describe a distorted octahedral coordination with two tridentate mono-deprotonated ligands. In vitro anticancer studies on MCF-7 human breast cancer cells reveal that the semicarbazone derivative along with its nickel complex is more active in the inhibition of cell proliferation than the thiosemicarbazone analogue.

Antineoplastic Agents↗
PubMed2005

Spectroscopic, thermal and electrochemical studies on some nickel(II) thiosemicarbazone complexes.

Several complexes of thiosemicarbazone derivatives with Ni(II) have been prepared. Structural investigation of the ligands and their complexes has been made based on elemental analysis, magnetic moment, spectral (UV-Vis, i.r., (1)H NMR, ms), and thermal studies. The i.r. spectra suggest the bidentate mononegative and tridentate (neutral, mono-, and binegative) behavior of the ligands. Different stereochemistries were suggested for the isolated complexes. The thermogravimetry (TG) and derivative thermogravimetry (DTG) have been used to study the thermal decomposition and kinetic parameters of some ligands and complexes using the Coats-Redfern and Horowitz-Metzger equations. The redox properties and stability of the complexes toward oxidation waves explored by cyclic voltammetry are related to the electron withdrawing or releasing ability of the substituent of thiosemicarbazone moiety. The samples displayed Ni(II)/Ni(I) couples irreversible waves associated with Ni(III)/Ni(II) process.

Electrochemistry↗
PubMed2004

Spectroscopic evaluation of manganese(II) complexes derived from semicarbazones and thiosemicarbazones.

Manganese(II) complexes having the general composition Mn(L)2X2 [where L=isopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC) and 4-aminoacetophenone thiosemicarbazone (LLD) and X=Cl-, 1/2SO(4)2-] have been synthesized. All the complexes were characterized by elemental analyses, molar conductance, magnetic moment susceptibility, EI-mass, 1H NMR, IR, EPR and electronic spectral studies. All the complexes show magnetic moments corresponding to five unpaired electrons. The possible geometries of the complexes were assigned on the basis of EPR, electronic and infrared spectral studies.

Chlorides↗
PubMed2004

Lanthanum(III) and praseodymium(III) complexes with isatin thiosemicarbazones.

Ten new lanthanum(III) and praseodymium(III) complexes of the general formula Na[La(L)2H2O] (Ln=La(III) or Pr(III); LH2=thiosemicarbazones) derived from the condensation of isatin with 4-phenyl thiosemicarbazide, 4-(4-chlorophenyl) thiosemicarbazide, 4-(2-nitrophenyl) thiosemicarbazide, 4-(2-bromophenyl) thiosemicarbazide and 4-(2-methylphenyl) thiosemicarbazide, have been synthesized in methanol in presence of sodium hydroxide. The XRD spectra of the complexes were monitored to verify complex formation. The complexes have also been characterized by elemental analysis, molar conductance, electronic absorption and fluorescence, infrared, far infrared, 1H and 13C NMR spectral studies. Thermal studies of these complexes have been carried out in the temperature range 25-800 degrees C using TG, DTG and DTA techniques. All these complexes decompose gradually with the formation of Ln2O3 as the end product. The Judd-ofelt intensity parameter, oscillator strength, transition probability, stimulated emission cross section for different transitions of Pr3+ for 4-phenyl thiosemicarbazones have been calculated.

Electrons↗
PubMed2005

Spectroscopic and biological studies on newly synthesized nickel(II) complexes of semicarbazones and thiosemicarbazones.

Nickel(II) complexes, having the general composition Ni(L)2X2, have been synthesized [where L: isopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC) and 4-aminoacetophenone thiosemicarbazone (LLD) and X=Cl-, 1/2SO(4)2-]. All the Ni(II) complexes reported here have been characterized by elemental analyses, magnetic moments, IR, electronic and mass spectral studies. All the complexes were found to have magnetic moments corresponding to two unpaired electrons. The possible geometries of the complexes were assigned on the basis of electronic and infrared spectral studies. Newly synthesized ligand and its nickel(II) complexes have been screened against different bacterial and fungal growth.

Anti-Infective Agents↗
PubMed2006

Structural and spectral perspectives of a novel thiosemicarbazone synthesized from di-2-pyridyl ketone and 4-phenyl-3-thiosemicarbazide.

A new thiosemicarbazone, HL is synthesized from di-2-pyridyl ketone and 4-phenyl-3-thiosemicarbazide and structurally and spectrochemically characterized. 1H NMR, 13C NMR, COSY, HMQC and IR spectra of the compound are studied and the proton magnetic resonance spectrum reveals some unprecedented observations. The thione form is predominant in the solid state, as supported by the crystal structure and IR data, while a thiol-thione equilibrium is proposed in the solution state by NMR studies. The compound crystallizes into a monoclinic lattice with space group C2/c and the ZE conformation is exhibited by the thiosemicarbazone. Intra- and intermolecular hydrogen-bonding interactions give rise to a two-dimensional packing in the crystal lattice.

Crystallography, X-Ray↗
PubMed2005

Manganese(II) complexes of substituted di-2-pyridyl ketone thiosemicarbazones: structural and spectral studies.

The reaction between manganese(II) acetate and two substituted thiosemicarbazones derived from di-2-pyridyl ketone (HL) in 1:2 molar ratio produces new complexes of general formula [MnL2]. The thiosemicarbazone moiety in HL deprotonates and gets coordinated to Mn(II) through the azomethine nitrogen, one of the pyridyl nitrogens, and the thiolate sulfur in both the complexes. The crystal structure of [MnL2(1)] was established by single crystal X-ray diffraction and the compound crystallizes into a monoclinic lattice with P2(1)/c space group. Manganese(II) exists in a distorted octahedral geometry in the complexes.

2,2'-Dipyridyl↗
PubMed2006

Spectral characterization of iron(III) complexes of 2-benzoylpyridine N(4)-substituted thiosemicarbazones.

Three iron(III) complexes (1-3) of 2-benzoylpyridine N(4)-phenyl thiosemicarbazone (HL1) and one iron(III) complex (4) of 2-benzoylpyridine N(4)-cyclohexyl thiosemicarbazone (HL2) were synthesized and characterized by means of different physicochemical techniques viz., molar conductivity measurements, magnetic susceptibility studies and electronic, infrared and EPR spectral studies. The analytical data and the molar conductance measurements of the complexes reveal that two molecules of the ligand and the anion are coordinated to the metal atom in all the four complexes. The magnetic moments of the complexes suggest that they are of low spin. From the infrared spectra of the ligands and the complexes it is confirmed that the ligands coordinate to iron(III) as an anion coordinating via the azomethine nitrogen, pyridyl nitrogen, and the thiolate sulphur. The EPR spectra of the complexes in the polycrystalline state at 298 and 110 K and in DMF solution at 110 K were recorded and all the spectra show three g values indicating that these complexes have rhombic distortion. All the iron(III) complexes in DMF solution at 110 K have similar anisotropic spectra with almost the same gav values, indicating that the bonding in all the complexes is similar and is unaffected by the coordination of the anion.

Electron Spin Resonance Spectroscopy↗
PubMed2004

Toxic effects of bis(thiosemicarbazone) compounds and its palladium(II) complexes on herpes simplex virus growth.

Here, we present data on the activity of benzyl bis(thiosemicarbazone); 3,5-diacyl-1,2,4-triazole bis(4-methylthiosemicarbazone) and their Pd(II) complexes against the replication of wild type and of acyclovir (ACV)-resistant, herpes simplex virus type 1 (HSV 1) and type 2 (HSV 2) strains. The data were compared to those under the action of acyclovir. The testing of cytotoxic activity suggests that these compounds may be endowed with important antiviral properties. It is interesting to note that the Pd(II)-benzyl bis(thiosemicarbazone) complex, 2, exhibits a significant activity against acyclovir-resistant viruses R-100 (HSV 1) and PU (HSV 2) with an in vitro selectivity index (SI) of 8.0 vs. 0.01 for acyclovir. This complex also negatively influenced the expression of key structural HSV 1 proteins (VP23, gH and gG/gD), thus suppressing simultaneously virus entry, transactivation of virus genome, capsid assembly, and cell-to-cell spread of infectious HSV progeny.

Acyclovir↗
PubMed1978

Inhibition of the RNA dependent DNA polymerase and the malignant transforming ability of Rous sarcoma virus by thiosemicarbazone-transition metal complexes.

Several thiosemicarbazone-metal complexes inhibit the RNA dependent DNA polymerase and the transforming ability of Rous sarcoma virus. Some complexes are equally as active as the free ligand whereas the activity of others is greatly enhanced. The 2-formyl pyridine thiosemicarbazone copper (II) complex is the most potent compound of this class that we tested. Some copper complexes of salicylaldehyde derivatives are very active also, particularly N-n-butyl, N-n-hexyl and N-benzylsalicylaldimine; no nickel complex of any salicylaldehyde compound is active. In addition, other metal ligands, such as dithizone, diacetyl bis (mercaptoethylimine), N-butyl thiocarbamate, 0,0' dimethyl dithiophosphate, potassium dithiooxalate, and cis-PtII(NH3)2Cl2 were tested with varying results.

Aldehydes↗
PubMed2000

Cu, Pt, and Pd complexes of the 3-deoxy-1,2-bis(thiosemicarbazone) derived from D-glucose.

3-Deoxy-D-erythro-hexos-2-ulose bis(thiosemicarbazone) (1) acts as a tetradentate ligand of the N2S2 type which forms stable coordination complexes with metal(II) cations. The Cu(II), Pt(II), and Pd(II) chelates (2, 4, and 6, respectively) of 1 were synthesized and characterized by elemental analysis and NMR spectroscopy. The NMR spectra of the Pt complex (4) showed the coupling of H-1 and C-1, C-2 of the bis(thiosemicarbazone) with 195Pt (33.7% naturally occurring), which supports the structure proposed for the chelate. The complexes 2, 4, and 6 were acetylated to give the corresponding tri-O-acetyl derivatives 3, 5, and 7. Elimination of Cu(II) from 3 with hydrogen sulfide afforded 8, the tri-O-acetyl derivative of 1. Preliminary studies have shown antiviral activity of chelates 2, 4, and 6 against poliovirus type 1.

Animals↗