Cytotoxicity of 2-aldo- and 2-ketopyridine-N(4)-substituted thiosemicarbazones and mode of action in human Tmolt4 cells.

The 2-aldo- and 2-ketopyridine-N(4)-substituted thiosemicarbazones and their copper complexes demonstrated potent cytotoxic activity against a series of murine and human suspended cultured tumor cells. Selected compounds were active against the growth of cultured cells from solid human tumors, i.e. Mck-7 breast effusion, lung A549 and lung MB-9812, bone SOS-2 and clear cell Caki renal tumor. In Tmolt4 T cell leukemia cells the compounds inhibited the syntheses of DNA, RNA and protein over 60 min at 25 to 100 microM. Multiple target sites in nucleic acid metabolism were suppressed by the agents, i.e. DNA polymerase alpha, ribonucleoside reductase, dihydrofolate reductase, de novo purine synthesis, thymidylate synthetase and nucleoside kinases. The total effects of the agents on DNA metabolism led to the reduction of deoxyribonucleotide pools as well as DNA fragmentation.

Spectral studies of semicarbazones derived from 3- and 4-formylpyridine and 3- and 4-acetylpyridine: crystal and molecular structure of 3-formylpyridine semicarbazone.

Semicarbazones derived from 3- and 4-formylpyridine (H3FoPyS, H4FoPyS) and 3- and 4-acetylpyridine (H3AcPyS, H4AcPyS) were prepared and studied spectroscopically. Complete NMR assignments for these semicarbazones were made using DEPT135, as well as HMQC and HMBC heteronuclear correlation techniques. The crystal and molecular structures of H3FoPyS were determined.

The cytotoxicity of symmetrical and unsymmetrical bis(thiosemicarbazones) and their metal complexes in murine and human tumor cells.

A number of thiosemicarbazones have been tested previously and herein are included three bis(thiosemicarbazones) for comparison to the previous derivatives. In general the uncomplexed thiosemicarbazones were more potent in the cytotoxic screens than the bis(thiosemicarbazone) except in the murine L1210 and the human colon SW480 screens. Mode of action studies have only demonstrated slight differences in the effects of the two types of compounds on nucleic acid metabolism. The symmetrical and unsymmetrical bis(thiosemicarbazones) complexes of copper, nickel, zinc, and cadmium have been examined to compare them to the heterocyclic N(4)-substituted thiosemicarbazones metal complexes. These new derivatives demonstrated excellent activity against the growth of suspended lymphomas and leukemias although it should be pointed out that generally they were not as active as the copper complexes of N(4)-substituted thiosemicarbazones. Nevertheless, selected bis(thiosemicarbazones) complexes were active against the growth of human lung MB9812, KB nasopharynx, epidermoid A431, glioma UM-86, colon SW480, ovary 1-A9, breast MCK-7, and osteosarcoma Saos-2. In human HL-60 promyelocytic leukemia cells the complexes preferentially inhibited DNA and purine syntheses over 60 min. The regulatory enzyme of the de novo purine pathway, IMP dehydrogenase, appeared to be a major target of the complexes. However, minor inhibition of the activities of DNA polymerase alpha, PRPP-amido transferase, ribonucleotide reductase, and nucleoside kinases occurred over the same time period. No doubt these effects of the complexes on nucleic acid metabolism were additive since the d[NTP] pool levels were reduced after 60 min as was DNA synthesis. The symmetrical and unsymmetrical bis(thiosemicarbazones) and their metal complexes did not cause as severe DNA fragmentation as the heterocyclic N(4)-substituted thiosemicarbazone metal complexes; furthermore, their metabolic effects in the tumor cell were more focused on a single synthetic pathway.

Synthesis and evaluation of copper radiopharmaceuticals with mixed bis(thiosemicarbazone) ligands.

Four "mixed" bis(thiosemicarbazone) derivatives of pyruvaldehyde were synthesized that incorporate two dissimilar thiosemicarbazone functions. The corresponding [67Cu]copper(II) complexes were prepared and evaluated as possible copper radiopharmaceuticals. The pyruvaldehyde-based mixed bis(thiosemicarbazone) ligands, CH3C[=NNHC(S)NHMe]CH[=NNHC(S)NHEt] (1), CH3C[=NNHC(S)NHMe] CH[=NNHC(S)NEt2] (2), CH3C[=NNHC(S)NHMe]CH[=NNHC(S)-cyclo-N(CH2)5] (3), and CH3C [=NNHC(S)NHMe]CH[=NNHC(S)-cyclo-N(CH2)6] (4), were obtained by reaction of the appropriate thiosemicarbazide derivative with pyruvaldehyde-2-N4-methylthiosemicarbazone (CH3C[=NNHC(S) NHMe]CHO). The 67Cu-labeled copper(II) complexes of ligands 1-4 were prepared and screened in a rat model to assess the potential of each chelate as a 62Cu-radiopharmaceutical for imaging with positron emission tomography. The 67Cu-complexes of ligands 1-4 exhibit significant uptake into the brain and heart 1 min following intravenous administration to rats. For the 67Cu-complexes of ligands 2, 3, and 4, the cerebral and myocardial uptake of 67Cu is two-to-threefold lower at 2 h than at 1 min postinjection, due to significant biological clearance of these 67Cu-chelates. However, the 67Cu-complex of 1 affords cerebral and myocardial uptake and retention comparable to that of [67Cu]Cu-PTSM in this model. Although the kinetics of this new agent appear attractive, ultrafiltration studies using solutions of dog and human serum albumin reveal that the 67Cu-complex of ligand 1, like Cu-PTSM, interacts more strongly with human albumin than dog albumin. Thus, this new agent would appear to offer no advantage over Cu-PTSM as a 62Cu-labeled tracer for evaluation of regional tissue perfusion.

Synthesis and characterization of Pd(II) and Pt(II) complexes of p-isopropylbenzaldehyde N-protected thiosemicarbazones. Cytotoxic activity against ras-transformed cells.

Cytotoxicity tests in tumor cells sensitive to cis-DDP (HL-60, JURKAT, Hela and 3T3) and in tumor cells transformed by ras oncogenes and resistant to cis-DDP (Pam 212-ras) show that cyclometallated complexes 1a [Pd(p-is.TSCN-NHMe)]4, 2b [Pt(p-is.TSCN-NMe2)]4 and 4a [Pd(p-is.TSCN-NHex)]4 may be endowed with specific cytotoxic properties. In fact, these three novel metal-thiosemicarbazone compounds kill Pam 212-ras cells through apoptosis induction. These results, together with others recently published, indicate that the design and synthesis of metallated-thiosemicarbazone compounds may lead to the discovery of novel antitumor agents able to circumvent cis-DDP resistance, in particular tumor cell lines.

The hypolipidemic activity of heterocyclic thiosemicarbazones, thioureas and their metal complexes in sprague dawley male rats.

Heterocyclic thiosemicarbazones, thioureas and their copper, nickel, and cobalt complexes were shown to be potent hypolipidemic agents in male Sprague Dawley rats at 8 mg/kg/day, orally. These agents lowered the activity of rat hepatic rate limiting enzymes for the synthesis of cholesterol and triglycerides. The effects of these agnets on cytoplasmic ATP-dependent citrate lyase, acetyl CoA synthetase and HMG-CoA reductase activities were reduced by a magnitude to explain the reduction of serum cholesterol levels afforded by the compounds. The reduction of acetyl CoA carboxylase, sn-glycerol-3-phosphate synthetase and phosphotidylate phosphohydrolase activities caused by the derivatives is of sufficient magnitude to explain the observed reduction in serum triglycerides after administration of the agents.

The cytotoxicity of 2-formyl and 2-acetyl-(6-picolyl)-4N-substituted thiosemicarbazones and their copper(II) complexes.

2-Acetyl-(6-picolyl)-4N-substituted thiosemicarbazones and their copper(II) complexes were shown to be potent antineoplastic and cytotoxic agents against murine and human cultured cells. Numerous derivatives were as active against solid tumor growth as clinically useful agents. The agents inhibited L1210 DNA and RNA syntheses with inhibition of key regulatory enzyme activities of the purine pathway as well as nucleoside kinase activities. d[NTP] pools were reduced and DNA strand scission occurred. These agents were DNA topoisomerase II inhibitors with lower IC50 values than that of VP-16. However, they did not cause L1210 DNA protein linked breaks and actually protected against those breaks afforded by VP-16. The agents were not synergistic with VP-16 in reducing cell growth or DNA synthesis although they did reduce growth of L1210 cells in agar suspended media.

The cytotoxicity of copper(II) complexes of 2-acetyl-pyridyl-4N-substituted thiosemicarbazones.

A series of 2-acetyl-pyridyl-4N-substituted thiosemicarbazones copper(II) complexes was evaluated for their cytotoxic mode of action in a variety of human and rodent tumor cell cultures. It was determined that these compounds may induce cytotoxicity by affecting several metabolic pathways including a reduction in de novo purine synthesis, and inhibition of IMP dehydrogenase, and DNA polymerase alpha activities. Selected compounds also demonstrated the ability to inhibit L1210 DNA topoisomerase II activity at micromolar concentrations. These agents were able to antagonize etoposide-induced formation of cleavable complexes as measured by K+/SDS precipitation and in vitro cleavage reactions.

Antineoplastic and Cytotoxic Activities of Nickel(II) Complexes of Thiosemicarbazones.

Nickel(II) complexes of thiosemicarbazons were observed to be potent cytotoxic agents in human and rodent tissue cultured tumor cells. Each compound demonstrated a slightly different profile in the various histological types of tumors. The nickel complex of Appip demonstrated the most potent in vivo activity in the Ehrlich ascites carcinoma. This agent selectively inhibited L1210 DNA and purine syntheses, and DNA polymerase alpha, PRPP-amido transferase, IMP-dehydrogenase, dihydrofolate reductase, TMP-kinase and thymidylate synthetase activities. L1210 DNA strand scission was evident and DNA viscosity was reduced after 24 hr incubation. The nickel complexes were not L1210 DNA topoisomerase II inhibitors.

Antineoplastic and cytogenetic effects of complexes of Pd (II) with 4N-substituted derivatives of 2-acetyl-pyridine-thiosemicarbazone.

The effect of novel Pd(II) complexes with derivatives of 2-acetyl-pyridinethisemicarbazone, N4-ethyl (HAc4Et) and 3-hexamethyleneiminylthiosemicarbazone (HAchexim), on Sister Chromatid Exchange (SCE) rates and human lymphocyte proliferation kinetics was studied. Also, the effect of Pd(II) complexes on DNA synthesis of P388 and L1210 cell cultures and against Leukemia P388 was investigated. Among these compounds, the compound Bis(3-hexamethyleneiminyl-2-acetylpyridine-thisemicarbazonato++ +) palladium (II) was found to be distinctly effective against Leukemia P388, in inhibiting incorporation of 3H-thymidine into DNA and in inducing SCEs and cell division delays.

The cytotoxicity of copper(II) complexes of heterocyclic thiosemicarbazones and 2-substituted pyridine N-oxides.

Thiosemicarbazone complexes of copper(II) were shown to be potent cytotoxic/antineoplastic agents against the growth of murine and human tumor cells. Selectivity of some agents was demonstrated against specific solid tumor growth. In L1210 lymphoid leukemia cells the copper complexes preferentially inhibited DNA synthesis with their major effects on the purine de novo pathway at PRPP amido transferase, IMP dehydrogenase and dihydrofolate reductase. The reductions of purines correlated positively with inhibition of DNA synthesis and cytotoxicity of the agents tested. DNA itself was fragmented after incubation with the drug; however, no binding of the agent to nucleotide bases or intercalation between base pairs was evident.

The cytotoxicity of heterocyclic thiosemicarbazones and their metal complexes on human and murine tissue culture cells.

Heterocyclic thiosemicarbazones, thioureas and 2-substituted pyridine N-oxides as well as representative nickel, cobalt and copper complexes were shown to be potent antineoplastic/cytotoxic agents. The cytotoxicity was demonstrated against single cell leukemia as well as cell lines derived from solid tissue (colon adenocarcinoma, HeLa, KB, skin, bronchogenic lung, bone osteosarcoma and glioma). In L1210 cells, DNA synthesis and subsequently RNA synthesis were particularly inhibited by the agents. IMP dehydrogenase activity and thus purine de novo synthesis was reduced significantly by the agents. Dihydrofolate reductase, ribonucleoside reductase, nucleoside kinase and DNA polymerase alpha activities were inhibited by the agents. d(NTP) pool levels were reduced by most of the agents. DNA strand scission was present with all of the derivatives; however, there was no evidence of intercalation, cross linking or alkylation/binding to bases of DNA. This new group of compounds may offer novel exploratory derivatives for future investigations in the treatment of cancer.

Antifungal and antitumor activity of heterocyclic thiosemicarbazones and their metal complexes: current status.

More than 75 substituted thiosemicarbazones and a number of metal complexes of each have been assayed for their antifungal activity. Their activity is significantly affected by the substituted groups attached at both 1N and 4N of the thiosemicarbazone moiety. Greatest activity occurs for 2-substituted pyridine thiosemicarbazones with differences observed for 2-formylpyridine, 2-acetylpyridine and 2-benzoylpyridine derivatives and their metal complexes. Further, there are activity differences for 4N-alkyl-, 4N-aryl-, 4N-dialkyl- and 3-azacyclothiosemicarbazones and their metal complexes as well as changes in the substituent size among each of these subgroups. Cu(II) complexes are often more active than the uncomplexed thiosemicarbazones, with the latter showing similar activity to Ni(II) complexes in many instances. The reduction potential of the thiosemicarbazone ligand in a Cu(II) complex, the strength of the ligand field and various spectral properties can be correlated to the inhibitory activity.

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.