In vitro evaluation of the metabolic enzymes and drug interaction potential of triapine.

PURPOSE: To investigate the metabolic pathways of triapine in primary cultures of human hepatocytes and human hepatic subcellular fractions; to investigate interactions of triapine with tenofovir and emtricitabine; and to evaluate triapine as a perpetrator of drug interactions. The results will better inform future clinical studies of triapine, a radiation sensitizer currently being studied in a phase III study. METHODS: Triapine was incubated with human hepatocytes and subcellular fractions in the presence of a number of inhibitors of drug metabolizing enzymes. Triapine depletion was monitored by LC-MS/MS. Tenofovir and emtricitabine were co-incubated with triapine in primary cultures of human hepatocytes. Triapine was incubated with a CYP probe cocktail and human liver microsomes, followed by LC-MS/MS monitoring of CYP specific metabolite formation. RESULTS: Triapine was not metabolized by FMO, AO/XO, MAO-A/B, or NAT-1/2, but was metabolized by CYP450s. CYP1A2 accounted for most of the depletion of triapine. Tenofovir and emtricitabine did not alter triapine depletion. Triapine reduced CYP1A2 activity and increased CYP2C19 activity. CONCLUSION: CYP1A2 metabolism is the major metabolic pathway for triapine. Triapine may be evaluated in cancer patients in the setting of HIV with emtricitabine or tenofovir treatment. Confirmatory clinical trials may further define the in vivo triapine metabolic fate and quantify any drug-drug interactions.

Anticancer potency of copper(II) complexes of thiosemicarbazones.

Being a structural and catalytic cofactor in a number of biological pathways, copper accumulates in tumors owing to selective permeability of the cancer cell membranes. Copper(II) ion forms the active centers in a large number of metalloproteins. The coordination of Schiff's base ligands to the metal ion results in the high extent of increase in anticancer activity. The copper(II) complexes can cleave DNA through oxidative and hydrolytic pathways, cell apoptosis via intrinsic reactive oxygen species (ROS) mediated mitochondrial pathway due to excessive production of ROS and hence, are found more active than Ni and Pt complexes. Flexible Cu(I/II) redox behavior helps the copper complexes to form more potent, clinically effective and less toxic copper based antiproliferative drugs of lower IC50 value and higher growth inhibitory activity. Copper(II) complexes of thiosemicarbazones of Isatin, Pyridine, Benzoyl pyridine, Diacetyl/Dimethyl glyoxal, Acetophenone/Acetoacetanalide, Thiazole/Pyrazole, Quinoline, Carboxybenzaldehyde, Cinnamaldehyde/Cuminaldehyde, Citronellal, Chromone, Pyridoxal, 8-Ethyl-2-hydroxytricyclo (7.3.1.02,7) tridecan-13-one, Acyl Diazines, Naphthalene, Proline, 5-Formyluracil, 2-Hydroxy-8-propyltricyclo (7.3.1.02,7) tridecan-13-one, 9-cis-Retinal, Curcumin, Helicin (Salicylaldehyde-ß-D-glucoside), Thiophene carboxaldehyde, Salicylaldehyde, Iminodiacetate, and 3-Formyl-4-hydroxy benzenesulfonic acid have been found to exhibit more anticancer activity toward HCT116, MCF7, A549, U937, HeLa, HepG2, SGC-7901, A2780 cell lines than that of their corresponding thiosemicarbazones and standard topoisomerase-II inhibitors.

Halogenated aromatic thiosemicarbazones as potent inhibitors of tyrosinase and melanogenesis.

A set of 21 halogenated thiosemicarbazones (TSCs) have been synthesized and its inhibitory properties toward activity diphenolase of mushroom tyrosinase and their ability to inhibition of melanogenesis in B16F10 murine, melanoma cell line have been investigated. The molecular docking to the active site of the enzyme has been also performed to investigate the nature of enzyme-inhibitor interactions. The obtained outcomes allowed us to perform SAR analysis. TSC 6, 12 and 21 exhibited the most potent inhibitory properties showing IC50 of 0.5, 0.9 and 0.8 µM, respectively. They revealed reversible and competitive manner of tyrosinase inhibition. According to SAR analysis, para-substituted acetophenone derivatives of thiosemicarbazones have the highest affinity to the enzyme among the investigated compounds. Melanin production in B16F10 cells was inhibited by all investigated compounds at the micromolar level. Suggested inhibition mechanism is based on the interaction between a sulfur atom of thiourea moiety of the thiosemicarbazones, and copper ions in the active site of the enzyme. These results might be useful in searching novel inhibitors of melanogenesis which could be used in the cosmetic and food industry.

An Accord of Nuclear Receptor Expression in CD4+ T Cells in Rheumatoid Arthritis.

Chronically activated CD4+ T cells drive uncontrolled inflammation, leading to tissue damage in various autoimmune disorders, such as rheumatoid arthritis (RA). Investigation of the molecular mechanisms involved in RA and recent analysis of transcriptomic profiles has implicated members of the nuclear receptor (NR) superfamily in RA. NRs are required for the development, differentiation, and effector function of CD4+ T cells; therefore, it is thought that NRs are important in shaping the CD4+ T cell repertoire and associated inflammation in RA. Despite their relevance, the full potential of the NR superfamily in RA, either as biomarkers or disease targets, has not been harnessed. To gain insight on the NR members that are closely associated with RA disease activity, we generated an expression atlas for the NR superfamily in CD4+ T cells isolated either in a steady state or over the course of collagen-induced arthritis mouse model of RA. We observed discrete expression patterns among the NR superfamily during the disease stages. NRs that instigate anti-inflammatory programs underwent major downregulation during disease onset; however, during the fully developed disease stage we noticed that NRs that induce proinflammatory programs had reduced transcript levels. These animal findings corroborated well with the expression patterns of NRs in clinical samples obtained from RA patients. Furthermore, we observed that targeting NRs using synthetic ligands alleviates the progression of collagen-induced arthritis. Overall, our data demonstrates the potential of the NR superfamily as novel therapeutic targets for the treatment of autoimmune disorders.

Zn-DTSM, A Zinc Ionophore with Therapeutic Potential for Acrodermatitis Enteropathica?

Acrodermatitis enteropathica (AE) is a rare disease characterised by a failure in intestinal zinc absorption, which results in a host of symptoms that can ultimately lead to death if left untreated. Current clinical treatment involves life-long high-dose zinc supplements, which can introduce complications for overall nutrient balance in the body. Previous studies have therefore explored the pharmacological treatment of AE utilising metal ionophore/transport compounds in an animal model of the disease (conditional knockout (KO) of the zinc transporter, Zip4), with the perspective of finding an alternative to zinc supplementation. In this study we have assessed the utility of a different class of zinc ionophore compound (zinc diethyl bis(N4-methylthiosemicarbazone), Zn-DTSM; Collaborative Medicinal Development, Sausalito, CA, USA) to the one we have previously described (clioquinol), to determine whether it is effective at preventing the stereotypical weight loss present in the animal model of disease. We first utilised an in vitro assay to assess the ionophore capacity of the compound, and then assessed the effect of the compound in three in vivo animal studies (in 1.5-month-old mice at 30 mg/kg/day, and in 5-month old mice at 3 mg/kg/day and 30 mg/kg/day). Our data demonstrate that Zn-DTSM has a pronounced effect on preventing weight loss when administered daily at 30 mg/kg/day; this was apparent in the absence of any added exogenous zinc. This compound had little overall effect on zinc content in various tissues that were assessed, although further characterisation is required to more fully explore the cellular changes underlying the physiological benefit of this compound. These data suggest that Zn-DTSM, or similar compounds, should be further explored as potential therapeutic options for the long-term treatment of AE.

Menkes disease: Oral administration of glyoxal-bis(N(4)-methylthiosemicarbazonato)-copper(II) rescues the macular mouse.

BACKGROUND: Menkes disease is a copper metabolism disorder caused by mutations in ATP7A, a copper-transporting P-type ATPase. In this study, oral copper supplementation via glyoxal-bis(N(4)-methylthiosemicarbazonato)-copper(II) (CuGTSM), a lipophilic copper complex, was investigated in male hemizygous macular (MoMl/y) mice, a mouse model of Menkes disease. METHODS: CuGTSM was administered by oral gavage on postnatal days 5, 8, 11, 17, 23, and 32. The copper levels in the organs and serum, copper-dependent enzyme activities in the brain, and ceruloplasmin (Cp) activity in the serum were measured at 15 days and 3 and 8 months of age. Histological analysis of the intestines and the rotarod test were also performed. RESULTS: CuGTSM treatment extended the lifespan of MoMl/y mice and partly restored the copper concentrations and cytochrome oxidase and DBH activities in the brain; however, the rotarod test showed impaired motor performance. The treatment also increased copper concentrations and Cp activity in the serum. In suckling MoMl/y mice, CuGTSM treatment transiently induced diarrhea accompanied by copper accumulation and altered villus morphology in the ileum. CONCLUSION: Oral administration of CuGTSM extended the lifespan of MoMl/y mice. Oral administration is attractive, but pharmaceutical studies are needed to reduce the adverse enteral effects.

Syntheses and evaluation of glucosyl aryl thiosemicarbazide and glucosyl thiosemicarbazone derivatives as antioxidant and anti-dyslipidemic agents.

A series of N-per-O-acetyl-glucosyl arylthiosemicarbazide and thiosemicarbazone derivatives have been synthesized and evaluated for their in vivo anti-dyslipidemic and in vitro antioxidant activities. Among 16 compounds tested, 3 compounds showed potent anti-dyslipidemic activity and 6 compounds showed potent antioxidant and scavenger of oxygen free radicals activity.

Selective intracellular release of copper and zinc ions from bis(thiosemicarbazonato) complexes reduces levels of Alzheimer disease amyloid-beta peptide.

Copper and zinc play important roles in Alzheimer disease pathology with recent reports describing potential therapeutics based on modulation of metal bioavailability. We examined the ability of a range of metal bis(thiosemicarbazonato) complexes (MII(btsc), where M=CuII or ZnII) to increase intracellular metal levels in Chinese hamster ovary cells overexpressing amyloid precursor protein (APP-CHO) and the subsequent effect on extracellular levels of amyloid-beta peptide (Abeta). The CuII(btsc) complexes were engineered to be either stable to both a change in oxidation state and dissociation of metal or susceptible to intracellular reduction and dissociation of metal. Treatment of APP-CHO cells with stable complexes resulted in elevated levels of intracellular copper with no effect on the detected levels of Abeta. Treatment with complexes susceptible to intracellular reduction increased intracellular copper levels but also resulted in a dose-dependent reduction in the levels of monomeric Abeta. Treatment with less stable ZnII(btsc) complexes increased intracellular zinc levels with a subsequent dose-dependent depletion of monomeric Abeta levels. The increased levels of intracellular bioavailable copper and zinc initiated a signaling cascade involving activation of phosphoinositol 3-kinase and c-Jun N-terminal kinase. Inhibition of these enzymes prevented Abeta depletion induced by the MII(btsc) complexes. Inhibition of metalloproteases also partially restored Abeta levels, implicating metal-driven metalloprotease activation in the extracellular monomeric Abeta depletion. However, a role for alternative metal-induced Abeta metabolism has not been ruled out. These studies demonstrate that MII(btsc) complexes have potential for Alzheimer disease therapy.

Basic characterization of 64Cu-ATSM as a radiotherapy agent.

64Cu-diacetyl-bis(N4-methylthiosemicarbazone) (64Cu-ATSM) is a promising radiotherapy agent for the treatment of hypoxic tumors. In an attempt to elucidate the radiobiological basis of 64Cu-ATSM radiotherapy, we have investigated the cellular response patterns in vitro cell line models. Cells were incubated with 64Cu-ATSM, and the dose-response curves were obtained by performing a clonogenic survival assay. Radiation-induced damage in DNA was evaluated using the alkali comet assay and apoptotic cells were detected using Annexin V-FITC and propidium iodide staining methods. Washout rate and subcellular distribution of 64Cu in cells were investigated to further assess the effectiveness of 64Cu-ATSM therapy on a molecular basis. A direct comparison of subcellular localization of Cu-ATSM was made with the flow tracer analog Cu-pyruvladehyde-bis(N4-methylthiosemicarbazone). In this study, 64Cu-ATSM was shown to reduce the clonogenic survival rate of tumor cells in a dose-dependent manner. Under hypoxic conditions, cells took up 64Cu-ATSM and radioactive 64Cu was highly accumulated in the cells. In the 64Cu-ATSM-treated cells, DNA damage by the radiation emitted from 64Cu was detected, and inhibition of cell proliferation and induction of apoptosis was observed at 24 and 36 h after the treatment. The typical features of postmitotic apoptosis induced by radiation were observed following 64Cu-ATSM treatment. The majority of the 64Cu taken up into the cells remained in the postmitochondrial supernatant (the cellular residue after removal of the nuclei and mitochondria), which indicates that the beta- particle emitted from 64Cu may be as effective as the Auger electrons in 64Cu-ATSM therapy. These data allow us to postulate that 64Cu-ATSM will be able to attack the hypoxic tumor cells directly, as well as potentially affecting the peripheral nonhypoxic regions indirectly by the beta- particle decay of 64Cu.

Anticonvulsant and neurotoxicity evaluation of some 6-substituted benzothiazolyl-2-thiosemicarbazones.

Various 6-substituted benzothiazolyl-2-thiosemicarbazones were synthesized and screened for anticonvulsant activity in maximal electroshock induced seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure models in mice. The neurotoxicity was assessed using the rotorod method. The 6-methyl benzothiazolyl-2-thiosemicarbazones showed anticonvulsant activity in both mice i.p. and rat oral MES screen. The 6-nitro benzothiazolyl thiosemicarbazone derivative 1a emerged as the most promising one with anti-MES activity in mice i.p., rat i.p. and rat p.o. evaluations. All the compounds exhibited lesser or no neurotoxicity compared to phenytoin. The isatinimino derivatives had shown better activity when compared to the benzylidene or acetophenone derivatives.

Anticonvulsant and neurotoxicity evaluation of some 6-chlorobenzothiazolyl-2-thiosemicarbazones.

Ten 6-chlorobenzothiazolyl-2-thiosemicarbazones were synthesised and screened for anticonvulsant and neurotoxic properties. Most of the compounds showed anticonvulsant activity against both maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole screens. Eight compounds have shown good protection in the rat p.o. MES test at 30 mg kg(-1). Compound 1 [4-(6-chlorobenzothiazol-2-yl)-1-(3-isatinimino)thiosemicarbazone] emerged as the most promising one with an ED(50) of 17.86 and 6.07 mg kg(-1) in mice i.p. and rat p.o., respectively. Compound 1 showed a weak ability to block the expression of fully kindled seizures.

Chagas' disease: a search for treatment and a question--should the disease be of military concern?

If military forces are required to operate in areas that are endemic for Chagas' disease, the occupation should be of critical concern. These areas, located in Central and South America, are many. The matter is of particular importance because no suitable drug exists to treat individuals who contract the disease. We examined 60 compounds of a chemical class, thiosemicarbazones, known to have some activity against the disease. The work was carried out using Trypanosoma cruzi-infected mice. Of the 60 potential drugs evaluated, 12 showed significant suppressive activity. One of these compounds was almost 50% greater than the reference drug used in the test system.

2-Acetylpyridine thiosemicarbazones. 8. Derivatives of 1-acetylisoquinoline as potential antimalarial agents.

A series of 1-acetylisoquinoline thiosemicarbazones was prepared in order to evaluate their antimalarial properties. This was achieved by the reaction of 1-acetylisoquinoline with methyl hydrazinecarbodithioate to give methyl 3-[1-(1-isoquinolinyl)ethylidene]hydrazinecarbodithioate (II). Displacement of the S-methyl group from this intermediate by various primary and secondary amines afforded the desired 1-acetylisoquinoline thiosemicarbazones (III). Thiosemicarbazides in which the azomethine moiety of the latter was reduced could be prepared by the reaction of II with NaBH4 to give methyl 3-[1-(1-isoquinolinyl)ethyl]hydrazinecarbodithioate (VIII). Reaction of VII with the appropriate amine gave 1-[1-(1-isoquinolinyl)ethyl]thiosemicarbazides (IX). Evaluation of the antimalarial activity of series III and IX in mice infected with Plasmodium berghei indicated that cures were attainable at dose levels of 40-160 mg/kg.

2-Acetylpyridine thiosemicarbazones. 9. Derivatives of 2-acetylpyridine 1-oxide as potential antimalarial agents.

In view of the antimalarial activity in mice of 2-acetylpyridine thiosemicarbazones, a series of analogous 1-oxides was prepared for evaluation. Their synthesis was achieved by the reaction of 2-acetylpyridine 1-oxide with methyl hydrazinecarbodithioate to give methyl 3-[1-(2-pyridinyl 1-oxide)ethylidene]hydrazinecarbodithioate (II). Reaction of the latter intermediate with secondary amines afforded the desired 2-acetylpyridine 1-oxide thiosemicarbazones (III). Reduction of the azomethine linkage of II with NaBH4 gave methyl 3-[1-(2-pyridinyl 1-oxide)ethyl]-hydrazinecarbodithioate (IV) whose S-methyl group was then displaced by amines to give a 1-[1-(2-pyridinyl 1-oxide)ethyl]thiosemicarbazide, V. Antimalarial activity of III was evaluated against both Plasmodium berghei in the mouse and Plasmodium falciparum in an automated in vitro test system. In both cases, 2-acetylpyridine 1-oxide thiosemicarbazones were found to be less active than the corresponding de-1-oxide analogues. When compounds V were evaluated against Plasmodium berghei in the mouse, a diminution of activity was similarly seen in comparison to the analogues not bearing the 1-oxide moiety.

Computer-based approach to chelation therapy: a theoretical study of some chelating agents for the selective removal of toxic metal ions from plasma.

COMICS is a computer programme for calculating equilibrium concentrations of metal complexes and reactive species in multi-metal-multi-ligand systems. Its usefulness for analysing metal ion equilibria in blood plasma has been improved by including albumin as a ligand. Using this model system the distribution and removal of copper(II) and zinc ions in histidinaemia, lead poisoning and Wilson's disease have been examined. The efficacy of TRIEN in removing excess copper(II) is shown. The use of specific tripeptides such as Gly-Gly-His methyl ester for the selective removal of copper(II) is suggested. A possible chemoprophylaxis of influenza based on complexation of zinc is discussed. Calculations confirm that thiosemicarbazones such as methisazone and 2-acetylpyridine thiosemicarbazone are effective competitors for heavy metal ions under physiological conditions.

Protection of carrageenin edema and trypsin hydrolysis of bovine serum albumin by naphthylthiosemicarbazides and their cyclized oxadiazoles.

Seven 1-(naphth-1-ylacetyl)-4-substituted thiosemicarbazides were synthesized and cyclized to the corresponding 2-(naphth-1-ylmethyl)-5-arylamino-1,3,4-oxadiazoles. All compounds, with the exception of two slbstituted oxadiazoles, possessed low anti-inflammatory activity. The protection afforded by these compounds against carrageen-in-induced edema ranged from 3 to 43% where cyclization, in general, decreased anti-inflammatory activity. All compounds (1 mM), possessed antiproteolytic activity where in vitro protection of trypsin-induced hydrolysis of bovine serum albumin, in most cases was greater with oxadiazoles.

Thiosemicarbazones and hydrazones of alpha-methylchalkone as potential chemotherapeutic agents.

The effectiveness of chalkones and derivatives as antibacterial and antifungal agents stimulated our interest in the possibility of coupling this type of compound with certain hydrazines and thiosemicarbazides to determine the potential chemotherapeutic activity of these combinations as anticancer and antimalarial agents. Accordingly, 18 hydrazine and thiosemicarbazide derivatives of alpha-methylchalkone (dypnone) have been synthesized for study as potential antitumor agents in animal tumor systems against Walker 256 carcinosarcoma (intramuscular) and leukemia L-1210 and for antimalarial activity against Plasmodium berghei in experimentally infected mice. Of the series of chalkone derivatives, significant inhibition in preliminary tests against the Walker 256 carcinosarcoma (intramuscular) rat tumor system was exhibited by alpha-methylchalkone-1,4-phthalazinediyldihydrazone and showed activity in the leukemia 1210 mouse tumor system. The guanylhydrazone of alpha-methylchalkone showed good inhibition with confirmed activity against Plasmodium berghei in experimentally infected mice.