Tetraphenylethylene-thiosemicarbazone based ultrafast, highly sensitive detection of hypochlorite in aqueous environments and dairy products.

We have designed and synthesised a novel fluorescent probe with a tetraphenylethylene (TPE) scaffold as an active fluorescent unit and thiosemicarbazide (TSC) group as a recognition unit. The probe, TPE-TSC, exhibited superior selectivity towards hypochlorite (ClO-) with a low limit of detection (2.0 nM). It also demonstrated a turn-off response for a brief period (<30 s) via an oxidation reaction. Furthermore, high-resolution mass spectrometry (HRMS) revealed that TPE-TSC reacted with ClO- by forming a carboxylic acid moiety in nearly 100% aqueous environments. More significantly, the probe detected ClO- in disinfectant, spiked milk samples, and spiked water samples. In all, TPE-TSC proposes an optimistic approach precisely for the determining the quality of milk and water contaminated with ClO- and trace amounts of ClO- in disinfectants.

Thiosemicarbazonate complexes with affinity for amyloid-ß fibers: synthesis, characterization and biological studies.

Aim: Obtain radioimages of amyloid-ß fibers using 99mTc-complexes. Methodology: Tridentate thiosemicarbazone and thiocarbonohydrazone ligands containing fragments (stilbene, azobenzene, benzothiazole or benzoxazole) with affinity for amyloid-ß fibers and its Re(I) complexes have been prepared. The molecular structures of several ligands and complexes were determined by x-ray diffraction. Binding affinity studies toward Aß1-42 fibers were performed for the ligands and Re(I) complexes. The ability of formation of some 99mTc(I) complexes, their biodistribution and in vivo stability have been established. Results & conclusion: Complexes of stilbene and benzothiazole thiosemicarbazonates show similar affinity for amyloid-ß fibers to the free ligand. These 99mTc complexes present a reasonable in vivo stability and a low capability to cross the blood-brain barrier although not sufficient to brain amyloid imaging.

Concentration of Fe(3+)-Triapine in BEAS-2B Cells.

An electron paramagnetic resonance (EPR) method was used to determine the concentration of the antitumor agent Triapine in BEAS-2B cells when Triapine was bound to iron (Fe). Knowledge of the concentration of Fe-Triapine in tumor cells may be useful to adjust the administration of the drug or to adjust iron uptake in tumor cells. An EPR spectrum is obtained for Fe(3+)-Triapine, Fe(3+)(Tp)2+, in BEAS-2B cells after addition of Fe(3+)(Tp)2+. Detection of the low spin signal for Fe(3+)(Tp)2+ shows that the Fe(3+)(Tp)2+ complex is intact in these cells. It is proposed that Triapine acquires iron from transferrin in cells including tumor cells. Here, it is shown that iron from purified Fe-transferrin is transferred to Triapine after the addition of ascorbate. To our knowledge, this is the first time that the EPR method has been used to determine the concentration of an iron antitumor agent in cells.

Comparison of metabolic pathways of different α-N-heterocyclic thiosemicarbazones.

Clinical failure of novel drugs is often related to their rapid metabolism and excretion. This highlights the importance of elucidation of their pharmacokinetic profile already at the preclinical stage of drug development. Triapine, the most prominent representative of α-N-heterocyclic thiosemicarbazones, was investigated in more than 30 clinical phase I/II trials, but the results against solid tumors were disappointing. Recent investigations from our group suggested that this is, at least partially, based on the fast metabolism and excretion. In order to establish more detailed structure/activity/metabolism relationships, herein a panel of 10 different Triapine derivatives was investigated for their metabolic pathways. From the biological point of view, the panel consists of terminally dimethylated thiosemicarbazones with nanomolar IC50 values, derivatives with micromolar cytotoxicities comparable to Triapine and a completely inactive representative. To study the oxidative metabolism, a purely instrumental approach based on electrochemistry/mass spectrometry was applied and the results were compared to the data obtained from microsomal incubations. Overall, the investigated thiosemicarbazones underwent the phase I metabolic reactions dehydrogenation, hydroxylation, oxidative desulfuration (to semicarbazone and amidrazone) and demethylation. Notably, dehydrogenation resulted in a ring-closure reaction with formation of thiadiazoles. Although strong differences between the metabolic pathways of the different thiosemicarbazones were observed, they could not be directly correlated to their cytotoxicities. Finally, the metabolic pathways for the most cytotoxic compound were elucidated also in tissues collected from drug-treated mice, confirming the data obtained by electrochemical oxidation and microsomes. In addition, the in vivo experiments revealed a very fast metabolism and excretion of the compound. Graphical abstract Structure/activity/metabolisation relationships for 10 anticancer thiosemicarbazones were established using electrochemical oxidation coupled to mass spectrometry (EC-MS) and human liver microsomes analyzed by LC-MS.

3-[(E)-(acridin-9'-ylmethylidene)amino]-1-substituted thioureas and their biological activity.

This paper describes the synthesis of a novel series of acridine thiosemicarbazones through a two-step reaction between various isothiocyanates and hydrazine followed by treatment with acridin-9-carbaldehyde. The properties of this series of seven new derivatives are studied using NMR and biochemical techniques, and the DNA-binding properties of the compounds are determined using spectrophotometric studies (UV-vis absorption, fluorescence, and circular/linear dichroism) and viscometry. The binding constants K are estimated as being in the range of 2.2 to 7.8×104M-1 and the percentage of hypochromism was found to be 22.11-49.75% (from UV-vis spectral titration). Electrophoretic experiments prove that the novel compounds demonstrate moderate inhibitory effects against Topo I activity at a concentration of 60×10-6M.

Lipophilicity Evaluation of Some N1-Arylidene-Thiosemicarbazones and 1,3,4-Thiadiazolines with Antimicrobial Activity.

A: The lipophilic character of 20 previously reported compounds-derivatives of N 1 -arylidene-thiosemicarbazone (series ) and their corresponding 1,3,4-thiadiazolines (series )-has been determined by reversed-phase thin-layer chromatography, using i -propanol-water mixtures as eluents. Principal component analysis (PCA) allowed an objective estimation of the retention behavior of the tested compounds and also afforded to obtain a 2D scatterplot, described by the first two principal components, which had the effect of separating the compounds from each other most effectively. With the use of clustering methods ( K -means clustering) based on PCA data, the studied compounds were grouped into two congeneric classes. When comparing the obtained lipophilicity parameters' values with the antibacterial properties of the tested compounds, we noticed that the lipophilic character had no significant influence on their growth inhibitory activity.

Prognostic significance of hypoxic PET using (18)F-FAZA and (62)Cu-ATSM in non-small-cell lung cancer.

OBJECTIVES: Tumor hypoxia is believed to have a strong correlation with the resistance to chemoradiotherapy. Noninvasive evaluation of hypoxic status in tumors using molecular imaging has the potential to characterize the tumor aggressiveness. We evaluated the clinical usefulness of newly-developed tumor hypoxic positron emission tomography (PET) tracers in localized non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Forty-seven patients with localized NSCLC received either or both hypoxic PETs using the tracers: (18)F-fluoroazomycin arabinoside ((18)F-FAZA) (n=45) and/or (62)Cu-diacetyl-bis (N4)-methylsemithiocarbazone ((62)Cu-ATSM) (n=22). All received (18)F-fluorodeoxyglucose ((18)F-FDG) PET tracer (n=47). We examined the correlation between uptake of three PET tracers and clinicopathological factors, and evaluated their impacts on survival after treatment retrospectively. RESULTS: A couple of commonly-identified unfavorable factors such as presence of vascular invasion and pleural invasion was significantly correlated with higher uptake of these hypoxic agents as well as that of (18)F-FDG. Larger tumor diameter, high neutrophil-to-lymphocyte ratio and advanced pathological stage were also associated with accumulation of hypoxic PETs ((18)F-FAZA, p<0.01; (62)Cu-ATSM, p<0.04), but not with that of (18)F-FDG. The patients with a higher accumulation had significantly poorer overall survival [(18)F-FAZA, HR (hazard ratio), 9.50, p<0.01; (62)Cu-ATSM, HR, 4.06, p<0.05] and progression free survival ((18)F-FAZA, HR, 5.28, p<0.01, (62)Cu-ATSM, HR, 2.72, p<0.05). CONCLUSION: Both (18)F-FAZA and (62)Cu-ATSM PET provide useful information regarding tumor aggressiveness and prediction of survival among NSCLC patients. We believe these hypoxic PETs could contribute to the establishment of the optimally individualized treatment of NSCLC.

Occupational Exposure to Veterinary Workers from the Positron Emission Tomography Imaging Agent 64Cu-ATSM.

Cu-ATSM is an emerging radiopharmaceutical for diagnostic use in positron emission tomography (PET), but to date there are no studies that assess the potential occupational doses to workers in either human or veterinary medicine. This study was aimed at determining the external radiation dose to veterinary workers from clinical PET/CT (PET combined with computed tomography) procedures using Cu-ATSM. To determine the dose to the workers, each worker was assigned two Electronic Personal Dosimeters (EPDs) to be worn on the chest and waist during the entirety of each procedure. The workers monitored during this study included a radiobiologist, a nuclear medicine technologist, an anesthesiologist, and a veterinary surgeon. Seven canine patients were imaged with an average mass of 33.7 kg (a range of 20.0-55.1 kg) with an average injected activity of 5 MBq kg. The dose range for the radiobiologist was 2-17 µSv (mean of 7.1 µSv), for the nuclear medicine technologist 0-14 µSv (mean of 5.6 µSv), for the anesthesiologist 0-12 µSv (mean of 4.0 µSv), and for the surgeon 0-10 µSv (mean of 3.6 µSv). In a comparison between the results of this study and published literature on occupational exposures from veterinary FDG PET/CT procedures, Cu-ATSM veterinary PET/CT procedures, on a per patient bias, exposed workers to less radiation.

Development of a sensitive HPLC method to measure in vitro permeability of E- and Z-isomeric forms of thiosemicarbazones in Caco-2 monolayers.

In the current study, we developed a HPLC method to quantitatively measure the permeability of the BpT-based chelators, 2-benzoylpyridine 4-ethyl-3-thiosemicarbazone (Bp4eT) and 2-benzoylpyridine 4-allyl-3-thiosemicarbazone (Bp4aT), across human colorectal adenocarcinoma (Caco-2) monolayers as a model of gut absorption. In aqueous solution, Bp4eT and Bp4aT formed inter-convertible Z and E isomers that were resolved by HPLC. Peak area was linear with respect to chelator concentration. Acceptable within-day and between-day precision (<22%) and accuracy (85-115% of true values) were obtained over a range of 1.0-100µM for Bp4eT and 1.5-300µM for Bp4aT. Limits of detection were 0.3µM and 1µM for Bp4eT and Bp4aT, respectively, while corresponding limits of quantification were 1µM and 5µM. Both chelators showed significant ability to chelate iron in THP-1 cells using a calcein-based assay and no apparent cytotoxicity was observed within 24h. Ratios of the apical to basolateral and basolateral to apical transport for Bp4eT were 1.10 and 0.89 at 100µM and 300µM respectively, indicating equal bi-directional movement of the compounds. Similarly, ratios were 0.77 and 0.92 for Bp4aT, respectively. This study demonstrates that Bp4eT and Bp4aT can be efficiently transported through Caco-2 cells and can potentially be formulated for oral delivery.

Carbazole-thiosemicarbazone-Hg(II) ensemble-based colorimetric and fluorescence turn-on toward iodide in aqueous media and its application in live cell imaging.

A carbazole-thiosemicarbazone-Hg(2+) ensemble-based fluorogenic probe for detection of iodide in aqueous media is reported. The first fluorescent sensor for iodide anions was constructed based on the displacement approach. An 'ensemble' is able to selectively sense iodide over other anions followed by the release of 9-(butane-1-yl)-9H-carbazole-3,6-dihydrazinecarbothioamide to give a remarkable change of fluorescence turn-on signal at pH 7.4 under aqueous media. The practical use of an 'ensemble' was demonstrated by its application to the detection of iodide in the living cells.

Subcellular localization of a fluorescent derivative of CuII(atsm) offers insight into the neuroprotective action of CuII(atsm).

Copper complexes of bis(thiosemicarbazone) (Cu(II)(btsc)s) have been studied as potential anti-cancer agents and hypoxia imaging agents. More recently, Cu(II)(btsc)s have been identified as possessing potent neuroprotective properties in cell and animal models of neurodegenerative disease. Despite their broad range of pharmacological activity little is known about how cells traffic Cu(II)(btsc)s and how this relates to potential anti-cancer or neuroprotective outcomes. One method of investigating sub-cellular localization of metal complexes is through confocal fluorescence imaging of the compounds in cells. Previously we harnessed the fluorescence of a pyrene group attached to diacetyl-bis(N4-methylthiosemicarbazonato)copper(ii)) (Cu(II)(atsm)), (Cu(II)L(1)). We demonstrated that Cu(II)L(1) was partially localized to lysosomes in HeLa cancer epithelial cells. Here we extend these studies to map the sub-cellular localization of Cu(II)L(1) in M17 neuroblastoma cells. Treatment of M17 or HeLa cells led to rapid association of the Cu-complex into distinct punctate structures that partially co-localized with lysosomes as assessed by co-localization with Lysotracker and acridine orange. No localization to early or late endosomes, the nucleus or mitochondria was observed. We also found evidence for a limited association of Cu(II)L(1) with autophagic structures, however, this did not account for the majority of the punctate localization of Cu(II)L(1). In addition, Cu(II)L(1) revealed partial localization with ER Tracker and was found to inhibit ER stress induced by tunicamycin. This is the first report to comprehensively characterize the sub-cellular localization of a Cu(II)(atsm) derivative in cells of a neuronal origin and the partial association with lysosome/autophagic structures and the ER may have a potential role in neuroprotection.

Synthesis of mono, bis-2-(2-arylideneaminophenyl) indole azomethines as potential antimicrobial agents.

A series of mono and bis 2-2-(arylidineaminophenyl)indole azomethines have been synthesized by a condensation reaction of 2-(2-amino phenyl) indole with various mono and diketones R-CO-R(l) /R-CO-X-CO-R(l) (1:1/2:1 ratio) in ethanol media. The synthesized azomethines were characterized via IR, (1)H-NMR, (13)C-NMR, MS and elemental analysis. The antimicrobial activity of these compounds against different bacteria and fungi was also evaluated.

Analytical properties of p-[N,N-bis(2-chloroethyl)amino]benzaldehyde thiosemicarbazone: spectrophotometric determination of palladium(II) in alloys, catalysts, and complexes.

p-[N,N-bis(2-chloroethyl)amino]benzaldehyde thiosemicarbazone (CEABT) is proposed as a new, sensitive, and selective analytical reagent for the spectrophotometric determination of palladium(II). The reagent reacts with palladium(II) in the pH range 1-2 to form a yellow-colored complex. Beer's law is obeyed in the concentration range up to 2.64 µg cm(-3). The optimum concentration range for minimum photometric error as determined by Ringbom's plot method is 0.48-2.40 µg cm(-3). The yellowish Pd(II)-reagent complex shows a maximum absorbance at 395 nm, with molar absorptivity of 4.05×10(4) dm3 mol(-1) cm(-1) and Sandell's sensitivity of the complex from Beer's data, for D=0.001, is 0.0026 µg cm(-2). The composition of the Pd(II)-CEABT reagent complex is found to be 1:2 (M-L). The interference of various cations and anions in the method were studied. The proposed method was successfully used for the determination of Pd(II) in alloys, catalysts, complexes, water samples, and synthetic alloy mixtures with a fair degree of accuracy.

Development of an LC-MS/MS method for analysis of interconvertible Z/E isomers of the novel anticancer agent, Bp4eT.

This study was focused on a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method development for quantification of a novel potential anticancer agent, 2-benzoylpyridine 4-ethyl-3-thiosemicarbazone (Bp4eT), in aqueous media. Solid Bp4eT was found to consist predominantly of the Z isomer, while in aqueous media, both isomers coexist. Sufficient separation of both isomers was achieved on a Synergi 4u Polar RP column with a mobile phase composed of 2 mM ammonium formate, acetonitrile, and methanol (30:63:7; v/v/v). The photo diode array analysis of both isomers demonstrated different absorption spectra which hindered UV-based quantification. However, an equal and reproducible response was found for both isomers using an MS detector, which enables the determination of the total content of Bp4eT (i.e., both E- and Z- isomeric forms) by summation of the peak areas of both isomers. 2-Hydroxy-1-naphthylaldehyde 4-methyl-3-thiosemicarbazone (N4mT) was selected as the internal standard. Quantification was performed in selective reaction monitoring using the main fragments of [M+H](+) (240 m/z for Bp4eT and 229 m/z for N4mT). The method was validated over 20-600 ng/ml. This procedure was applied to a preformulation study to determine the proper vehicle for parenteral administration. It was found that Bp4eT was poorly soluble in aqueous media. However, the solubility can be effectively improved using pharmaceutical cosolvents. In fact, a 1:1 mixture of PEG 300/0.14 M saline markedly increased solubility and may be a useful drug formulation for intravenous administration. This investigation further accelerates development of novel anticancer thiosemicarbazones. The described methods will be useful for analogs currently under development and suffering the same analytical issue.

Spectral, thermal, electrochemical and analytical studies on Cd(II) and Hg(II) thiosemicarbazone complexes.

The coordination characteristic of the investigated thiosemicarbazones towards hazard pollutants, Cd(II) and Hg(II), becomes the first goal. Their complexes have been studied by microanalysis, thermal, electrochemical and spectral (electronic, IR and MS) studies. The substitutent (salicylaldehyde, acetophenone, benzophenone, o-hydroxy-p-methoxybenzophenone or diacetylmonoxime) plays an important role in the complex formation. The coordination sites were the S for thiosemicarbazide (HTS); NN for benzophenone thiosemicarbazone (HBTS); NS for acetophenone thiosemicarbazone (HATS) and salicylaldehyde thiosemicarbazone (H2STS); NNS or NSO for diacetylmonoxime thiosemicarbazone (H2DMTS). The stability constants of Hg(II) complexes were higher than Cd(II). The kinetic and thermodynamic parameters for the different thermal decomposition steps in the complexes have been evaluated. The activation energy values of the first step ordered the complexes as: [Cd(H2STS)Cl2]H2O > [Cd(H2DAMTS)Cl2] > [Cd(HBTS)2Cl2]2H2O > [Cd(HATS)2Cl2]. The CV of [Cd(H2STS)Cl2]H2O and [Hg(HBTS)Cl2] were recorded. The use of H2DMTS as a new reagent for the separation and determination of Cd(II) ions from water and some synthetic samples using flotation technique is aimed to be discussed.

Spectral and structural studies of copper(II) complexes of thiosemicarbazones derived from salicylaldehyde and containing ring incorporated at N(4)-position.

Mononuclear and binuclear copper(II) complexes (1-8) with two ONS donor thiosemicarbazone ligands {salicylaldehyde 3-hexamethyleneiminyl thiosemicarbazone [H2L1] and salicylaldehyde 3-tetramethyleneiminyl thiosemicarbazone [H2L2]} have been prepared and physico-chemically characterized. IR, electronic and EPR spectra of the complexes have been obtained. The thiosemicarbazones bind to metal as dianionic ONS donor ligands in all the complexes except in [Cu(HL1)2] (2) and [Cu(HL2)2] (6). In compounds 2 and 6 the ligands are coordinated as monoanionic HL- ones. The magnetic susceptibility measurements indicate that all the complexes are paramagnetic. In complex [(CuL1)2] (1), the magnetic moment value is lower than the expected spin only value. In all the complexes g(||)>g( perpendicular)>2.0023 and G values within the range 2.5-3.5 are consistent with dx2-y2 ground state. The complexes were given the formula as [(CuL1)2] (1); [Cu(HL1)2] (2); [CuL1bpy] (3); [CuL1phen] (4); [CuL1gamma-pic].2H2O (5); [Cu(HL2)2] (6); [CuL2py].3H2O (7); [CuL2bipy] (8). The structure of the compound 8 have been solved by single crystal X-ray crystallography and was found to be distorted square pyramid around copper(II) ion.

Similarities and differences between azomethines and ketimines: synthesis, materials characterization and structure of novel imines compounds.

Imines (ketimines and azomethines) derived from p-dibenzoylbenzene (DB) and terephthalic aldehyde (TA) and two aromatic amines: aniline and 2,6-dimethylaniline have been investigated. Compounds were synthesized via condensation of amines with carbonyl monomers in DMA or amine solution. When using DMA as a solvent, azomethines with high yields were obtained. On the other hand, the amines used as a monomers served also as an effective solvent for the synthesis of the ketanils. This different reactivity of the aldehyde and ketone groups in DMA and in amine depends on the dehydration mechanism being dominated by a kinetic process or thermodynamic one. On the basis of FTIR, 13C and 1H NMR, UV-vis spectra, thermal characteristic and theoretical calculations conclusions are drawn regarding the similarities and differences between azomethines and ketimines.

Preparation of [61Cu]-2-acetylpyridine thiosemicarbazone complex as a possible PET tracer for malignancies.

Due to the interesting anti-proliferative properties of copper-thiosemicarbazone complexes, the production of a (61)Cu-labeled thiosemicarbazone, i.e. 2-acetylpyridine thiosemicarbazone (APTS) was investigated. Copper-61 (T(1/2)=3.33 h) was produced via the (64)Zn(p,alpha)(61)Cu nuclear reaction using a natural zinc target irradiated with 22 MeV protons for 500 microAh. The (61)Cu was separated from the irradiated target material by a two-step method and converted to acetate; this yielded a final activity of 222 GBq (6.0 Ci), with a radiochemical yield of >95%. The (61)Cu-acetate was mixed with 2-acetylpyridine thiosemicarbazone for 30 min at room temperature to yield [(61)Cu]APTS with a radiochemical yield of more than 80%. Colorimetric methods showed that residual chemical impurities in the product were below the accepted limits. Radio thin layer chromatography (RTLC) showed a radiochemical purity of more than 99% after C(18) column chromatography. A specific activity of about 370-740 MBq/mmol (10-20 Ci/mmol) was obtained. The stability of the final product was checked in the absence and presence of human serum at 37 degrees C for up to 3 h. The partition coefficient of the final complex was also determined.

[Study of the characterization of beta-cyclodextrin-acetylferrocene-thiosemicarbazone inclusion complex and micro-environmental effects].

Inclusion complex of acetylferrocene-thiosemicarbazone(TAF) with beta-cyclodextrin(beta-CD) has been prepared by using kneading method. Elemental analysis and the solubility determination proved that 1:1 inclusion complex has been formed. Characterization of the inclusion complex was studied by UV, FTIR, and X-ray diffractometry. The association constant was calculated to be 227 L x mol(-1) from the straight portion of the phase-solubility diagram. Furthermore, the influence of different solvents and pH on UV spectrum of acetylferrocene-thiosemicarbazone and beta-CD -TAF was discussed respectively. The results show that different micro-environment has apparently different effects on electric spectra of guest and inclusion complexes.

Adsorptive stripping voltammetric behaviour of azomethine group in pyrimidine-containing drugs.

The stripping voltammetric behaviour of buspirone hydrochloride (BUS) and piribedil (PIR), as models of pyrimidine-containing compounds, was studied using a hanging mercury drop electrode (HMDE). A sensitive adsorptive stripping voltammetric method for determination of such drugs is described. The voltammetric peaks were obtained at -1.23 and -1.22 V for BUS and PIR. respectively, which correspond to the reduction of the azomethine group of pyrimidine ring in Britton-Robinson buffer (pH 7). Factors such as pH of supporting electrolyte, accumulation potential and time and instrumental parameters were optimized. Calibration plots and regression data validation, accuracy, precision, limits of detection, limits of quantification, and other aspects of analytical merit are presented. The applicability of the method was evaluated through determination of BUS and PIR in tablet dosage forms. A preliminary study of the analysis of plasma samples, spiked with the investigated drug, after a simple extraction procedure is described.