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1.
Dalton Trans ; 53(31): 12951-12961, 2024 Aug 06.
Article in English | MEDLINE | ID: mdl-38842058

ABSTRACT

Four new copper(II) complexes were synthesized and characterized with the general formula [Cu(N-N)(Th)(NO3)], where N-N corresponds to the N-heterocyclic ligands 1,10-phenanthroline (phen), 2,2'-bipyridine (bipy), 4,7-diphenyl-1,10-phenanthroline (dpp), and 4,4-dimethyl-2,2'-bipyridine (dmbp) and Th represents the N,N-dibenzyl-N'-benzoylthiourea. Cytotoxic activities of the complexes against HCT116 (human colon carcinoma), HepG2 (human hepatocellular carcinoma), and non-tumor MRC-5 (human lung fibroblast) cells were investigated. The copper(II) complexes 1-4 were characterized by spectroscopic techniques while complexes 1 and 2 were studied using single-crystal X-ray diffraction as well. The complexes possessed a five-coordinated structure with one nitrate ligand as a monodentate at the axial position and two bidentate ligands N-heterocyclic and N,N-dibenzyl-N'-benzoylthiourea. The complexes showed promising IC50 values, ranging from 0.3 to 9.0 µM. Furthermore, interaction studies with biomolecules such as calf thymus DNA (ct-DNA) and Bovine Serum Albumin (BSA), which can act as possible biological targets of the complexes, were carried out. The studies suggested that the compounds interact moderately with ct-DNA and BSA. Complexes 1, 2, and 4 did not lead to cell accumulation at any stage of the cell cycle but caused a significant increase in internucleosomal DNA fragmentation. Whereas, compound 3 caused cell cycle arrest in the S phase while doxorubicin caused cell cycle arrest in the G2/M phase. The effect of structural modifications on the metal compounds was correlated with their biological properties and it was concluded that an increase in biological activity occurred with increasing the extension of the diimine ligands. Thus, complex 3 was the most promising one.


Subject(s)
Antineoplastic Agents , Cell Cycle , Coordination Complexes , Copper , DNA , Serum Albumin, Bovine , Thiourea , Copper/chemistry , Copper/pharmacology , Humans , Serum Albumin, Bovine/chemistry , Serum Albumin, Bovine/metabolism , DNA/metabolism , DNA/chemistry , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/chemical synthesis , Coordination Complexes/pharmacology , Coordination Complexes/chemistry , Coordination Complexes/chemical synthesis , Cattle , Thiourea/chemistry , Thiourea/pharmacology , Cell Cycle/drug effects , Animals , Imines/chemistry , Imines/pharmacology , Drug Screening Assays, Antitumor , Cell Proliferation/drug effects , Molecular Structure
2.
J Mol Graph Model ; 129: 108760, 2024 06.
Article in English | MEDLINE | ID: mdl-38513601

ABSTRACT

A new iminophosphorane-thiourea superbase was rationally designed and investigated as an organocatalyst for the enantioselective Michael addition reaction of nitromethane to 4-phenylbut-3-en-2-one. Starting from an iminophosphorane-thiourea organocatalyst structure already known, we have used theoretical calculations to determine the structures of transition states involved in the carbon-carbon bond formation step and carried out structural modifications to accelerate the reaction rate and to increase the enantioselectivity. The effective structural modification was adding a rigid hydroxyl group able to make an additional hydrogen bond to the transition state, producing a substantial decrease of the ΔG‡ by 7 kcal mol-1. The enantiomeric excess is predicted to be above of 97% using the reliable M06-2X and ωB97M - V functionals. The determination of the complete reaction mechanism and free energy profile was followed by a detailed microkinetic analysis. The present study points out a new direction for structural modifications on this kind of organocatalyst.


Subject(s)
Carbon , Thiourea , Hydrogen Bonding , Catalysis , Stereoisomerism , Thiourea/chemistry
3.
Curr Med Chem ; 31(29): 4703-4724, 2024.
Article in English | MEDLINE | ID: mdl-38375848

ABSTRACT

Tuberculosis (TB) remains a primary global health concern, necessitating the discovery and development of new anti-TB drugs, mainly to combat drug-resistant strains. In this context, thiourea derivatives have emerged as promising candidates in TB drug discovery due to their diverse chemical structures and pharmacological properties. This review aimed to explore this potential, identifying and exploring molecular targets for thiourea derivatives in Mycobacterium tuberculosis (Mtb) and the potential application of virtual screening techniques in drug discovery. We have compiled a comprehensive list of possible molecular targets of thiourea derivatives in Mtb. The enzymes are primarily involved in the biosynthesis of various cell wall components, including mycolic acids, peptidoglycans, and arabinans, or targets in the branched-chain amino acid biosynthesis (BCAA) pathway and detoxification mechanisms. We discuss the potential of these targets as critical constituents for the design of novel anti-TB drugs. Besides, we highlight the opportunities that virtual screening methodologies present in identifying potential thiourea derivatives that can interact with these molecular targets. The presented findings contribute to the ongoing efforts in TB drug discovery and lay the foundation for further research in designing and developing more effective treatments against this devastating disease.


Subject(s)
Antitubercular Agents , Drug Discovery , Mycobacterium tuberculosis , Thiourea , Thiourea/chemistry , Thiourea/pharmacology , Mycobacterium tuberculosis/drug effects , Antitubercular Agents/chemistry , Antitubercular Agents/pharmacology , Humans , Tuberculosis/drug therapy , Tuberculosis/microbiology , Tuberculosis/diagnosis , Drug Evaluation, Preclinical
4.
Chirality ; 34(6): 877-886, 2022 06.
Article in English | MEDLINE | ID: mdl-35303374

ABSTRACT

We report herein the synthesis and application of enantiopure C2 -symmetric primary amine-1,3-bis-thiourea organocatalysts in enantioselective conjugate 1,4-Michael addition of carbonyl containing nucleophiles, to nitroalkenes and N-phenylmaleimide, leading to final products in good enantioselectivities (up to 99%) and yields (up to 99%). We propose supramolecular noncovalent interactions within the organocatalyst's cleft between the substrate and the catalyst, via hydrogen bonding. Supramolecular interaction thus lowers the transition state energy mimicking an enzyme. Mechanism underlying our experimental results is supported by theorical calculations.


Subject(s)
Alkenes , Thiourea , Alkenes/chemistry , Catalysis , Nitro Compounds/chemistry , Stereoisomerism , Thiourea/chemistry
5.
Dalton Trans ; 51(4): 1489-1501, 2022 Jan 25.
Article in English | MEDLINE | ID: mdl-34989381

ABSTRACT

We have synthesized and characterized three new ruthenium(II) diphosphine complexes containing an acylthiourea ligand, with the general formula [Ru(DPEPhos)(O,S)(bipy)]PF6, where DPEPhos = bis(2-(diphenylphosphino)phenyl)ether, bipy = 2,2'-bipyridine, and O,S = N,N-dimethyl-N'-(benzoyl)thiourea (1), N,N-dimethyl-N'-(furoyl)thiourea (2), and N,N-dimethyl-N'-(thiophenyl)thiourea (3), by several physicochemical techniques. We evaluated the ruthenium complexes for their cytotoxicity against two human cancer cell lines, A549 (lung) and MDA-MB-231 (breast), and two corresponding lines of non-cancer cells, MRC-5 (lung) and MCF-10A (breast). All the complexes are cytotoxic against the cancer cell lines; the IC50 values lie in the micromolar range (0.07-0.70 µM). Ruthenium complex 1 is more selective (7 times more active) toward lung cancer cells (A549) than toward non-cancer cells (MRC-5) and is 160 times more cytotoxic than cisplatin against A549 cells. Investigations of the mechanism of action of complex 1 in A549 cells demonstrated that it inhibits colony formation and promotes cell cycle arrest in the G1 phase and apoptotic cell death. DNA binding studies revealed that complexes 1-3 interact with the biomolecule via minor grooves. These complexes also interact with human serum albumin (HSA) and have affinity for site I by hydrophobic forces. Therefore, this new class of ruthenium complexes can act as cytotoxic agents, mainly for lung cancer treatment.


Subject(s)
Breast Neoplasms/drug therapy , Coordination Complexes/pharmacology , Lung Neoplasms/drug therapy , Ruthenium Compounds/pharmacology , Thiourea/analogs & derivatives , Cell Line, Tumor , Coordination Complexes/chemical synthesis , Coordination Complexes/therapeutic use , Female , Humans , Ruthenium Compounds/chemical synthesis , Ruthenium Compounds/therapeutic use , Thiourea/chemistry
6.
Molecules ; 26(2)2021 Jan 12.
Article in English | MEDLINE | ID: mdl-33445529

ABSTRACT

Room temperature ionic liquids (RTILs) have been widely used as (co)solvents in several catalytic processes modifying, in most of the cases, the catalyst activity and/or the selectivity for the studied reactions. However, there are just a few examples of their use in hydrogen bonding organocatalysis. In this paper, we show the positive effect of a set of imidazole-based ionic liquids ([bmim]BF4 and [hmim]PF6) in the enantioselective addition of formaldehyde tert-butylhydrazone to prochiral α-keto esters catalyzed by a sugar-based chiral thiourea. Reactions performed in the presence of low percentages of RTILs led to an increase of the catalyst activity, thereby making possible to work at lower temperatures. Thus, the chiral tert-butyl azomethyl tertiary alcohols could be obtained with moderate to good conversions and higher enantioselectivities for most of the studied substrates when using up to 30 vol% of [hmim]PF6 as a cosolvent in processes performed in toluene.


Subject(s)
Ionic Liquids/chemistry , Temperature , Catalysis , Hydrazones/chemistry , Models, Molecular , Stereoisomerism , Thiourea/chemistry
7.
Chirality ; 33(1): 22-36, 2021 01.
Article in English | MEDLINE | ID: mdl-33232537

ABSTRACT

In this study, the novel bifunctional homochiral thiourea-L-prolinamides 1-4, tertiary amino-L-prolinamide 5, and bis-L-prolinamides 6 and 7 were prepared from enantiomerically pure (11R,12R)-11,12-diamino-9,10-dihydro-9,10-ethanoanthracene 8 and (11S,12S)-11,12-diamino-9,10-dihydro-9,10-ethanoanthracene ent-8. Highly enantioselective and diastereoselective aldolic intermolecular reactions (up to 95% enantiomeric excess, 93:7 anti/syn) between aliphatic ketones (20 equiv) and a range of aromatic aldehydes (1 equiv) were successfully carried out in the presence of water (10 equiv) and monochloroacetic acid (10 mol%), solvent-free conditions, at room temperature over 24 h using organocatalysts 1-7 (5 mol%). Stereoselective induction using density functional theory-based methods was consistent with the experimental data.


Subject(s)
Aldehydes/chemistry , Proline/analogs & derivatives , Acetone/chemistry , Catalysis , Chemistry Techniques, Synthetic , Density Functional Theory , Ketones/chemistry , Molecular Structure , Proline/chemical synthesis , Proline/chemistry , Solvents , Stereoisomerism , Thiourea/chemistry
8.
Lett Appl Microbiol ; 71(6): 645-651, 2020 Dec.
Article in English | MEDLINE | ID: mdl-32725897

ABSTRACT

Following the appearance of several antimicrobial agents to control the spread of infections, two major challenges have emerged: (i) the occurrence and blowout of multiresistant bacteria and the increase of chronic diseases and (ii) difficult-to-eradicate infections. In this study, we tested five benzoylthiourea derivatives for their ability to inhibit and stop bacterial growth and evaluated the possible influence of 1,2,4-triazolyl-benzoylthiourea derivative 4 on the formation and eradication of Staphylococcus aureus biofilms. Benzoylthiourea derivatives 4, 6, 10, 11 and 13 were obtained in one or two steps with low cost and subjected to tests to identify their minimum inhibitory concentration (MIC) and minimum bactericidal concentration. In vitro tests were also performed to assess their effects on biofilm formation and in preformed biofilms and scanning electron microscopy was used to visualize the effects on biofilm formation. The 1,2,4-triazolyl-benzoylthiourea derivative 4 showed bacteriostatic activity against the S. aureus HU25 clinical strain with an MIC of 16 µg ml-1 , which is below the toxic concentration (at 2500 µg ml-1 , 62·25% of the cells remained viable). Compound 4 also effectively prevented biofilm formation at the three subinhibitory concentrations tested (1/2 MIC, 1/4 MIC and 1/8 MIC) as confirmed by scanning electron microscopy. For breakdown of formed biofilms, the main influence was at a subinhibitory concentration (1/2 MIC). These findings make compound 4 a strong candidate for studies on the development of new antimicrobial and antibiofilm agents.


Subject(s)
Anti-Bacterial Agents/pharmacology , Biofilms/drug effects , Staphylococcus aureus/drug effects , Thiourea/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Humans , Microbial Sensitivity Tests , Plankton/drug effects , Plankton/growth & development , Plankton/physiology , Staphylococcal Infections/microbiology , Staphylococcus aureus/growth & development , Staphylococcus aureus/physiology , Thiourea/chemistry
9.
Med Chem ; 16(1): 93-103, 2020.
Article in English | MEDLINE | ID: mdl-30526466

ABSTRACT

BACKGROUND: New drugs and strategies to treat tuberculosis (TB) are urgently needed. In this context, thiourea derivatives have a wide range of biological activities, including anti-TB. This fact can be illustrated with the structure of isoxyl, an old anti-TB drug, which has a thiourea as a pharmacophore group. OBJECTIVE: The aim of this study is to describe the synthesis and the antimycobacterial activity of fifty-nine benzoylthioureas derivatives. METHODS: Benzoylthiourea derivatives have been synthesized and evaluated for their activity against Mycobacterium tuberculosis using the MABA assay. After that, a structure-activity relationship study of this series of compounds has been performed. RESULTS AND DISCUSSION: Nineteen compounds exhibited antimycobacterial activity between 423.1 and 9.6 µM. In general, we observed that the presence of bromine, chlorine and t-Bu group at the para-position in benzene ring plays an important role in the antitubercular activity of Series A. These substituents were fixed at this position in benzene ring and other groups such as Cl, Br, NO2 and OMe were introduced in the benzoyl ring, leading to the derivatives of Series B. In general, Series B was less cytotoxic than Series A, which indicates that the presence of a substituent at benzoyl ring contributes to an improvement in both antimycobacterial activity and toxicity profiles. CONCLUSION: Compound 4c could be considered a good prototype to be submitted to further structural modifications in the search for new anti-TB drugs, since it is 1.8 times more active than the first line anti-TB drug ethambutol and 0.65 times less active than isoxyl.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Design , Mycobacterium tuberculosis/drug effects , Thiourea/pharmacology , Animals , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Cell Line , Cell Survival/drug effects , Dose-Response Relationship, Drug , Macaca mulatta , Microbial Sensitivity Tests , Molecular Structure , Mycobacterium tuberculosis/growth & development , Structure-Activity Relationship , Thiourea/analogs & derivatives , Thiourea/chemistry
10.
Molecules ; 24(18)2019 Sep 18.
Article in English | MEDLINE | ID: mdl-31540462

ABSTRACT

In this investigation, the reaction of 2-dithiomethylcarboimidatebenzothiazole with a series of six chiral amino-acids was studied. The reaction proceeds through the isolable sodium salt of SMe-isothiourea carboxylates as intermediates, whose reaction with methyl iodide in stirring DMF as solvent affords SMe-isothiourea methyl esters. The presence of water in the reaction leads to the corresponding urea carboxylates as isolable intermediates, whose methyl esters were obtained. Finally, the urea N-methyl amide derivatives were isolated when SMe-isothiourea or urea methyl esters were reacted with methylamine in the presence of water. The structures of synthesized compounds were established by 1H and 13C nuclear magnetic resonance and the structures of SMe-isothiourea methyl esters derived from (l)-glycine, (l)-alanine, (l)-phenylglycine, and (l)-leucine, by X-ray diffraction analysis. This methodology allows to functionalize 2-aminobenzothiazole with SMe-isothiourea, urea, and methylamide groups derived from chiral amino acids to get benzothiazole derivatives containing coordination sites and hydrogen bonding groups. Further research on the biological activities of some of these derivatives is ongoing.


Subject(s)
Amino Acids/chemistry , Benzothiazoles/chemistry , Thiourea/chemistry
11.
Molecules ; 22(8)2017 Aug 10.
Article in English | MEDLINE | ID: mdl-28796165

ABSTRACT

The application of six novel α,ß-dipeptides as chiral organocatalysts in the asymmetric Michael addition reaction between enolizable aldehydes and N-arylmaleimides or nitroolefins is described. With N-arylmaleimides as substrates, the best results were achieved with dipeptide 2 as a catalyst in the presence of aq. NaOH. Whereas dipeptides 4 and 6 in conjunction with 4-dimethylaminopyridine (DMAP) and thiourea as a hydrogen bond donor proved to be highly efficient organocatalytic systems in the enantioselective reaction between isobutyraldehyde and various nitroolefins.


Subject(s)
Dipeptides/chemistry , 4-Aminopyridine/analogs & derivatives , 4-Aminopyridine/chemistry , Aldehydes/chemistry , Alkenes/chemistry , Catalysis , Hydrogen Bonding , Maleimides/chemistry , Nitro Compounds/chemistry , Solvents , Stereoisomerism , Thiourea/chemistry
12.
J Environ Manage ; 188: 18-25, 2017 Mar 01.
Article in English | MEDLINE | ID: mdl-27918923

ABSTRACT

In this work, chitin (CTN), chitosan (CTS) and activated carbon (AC) were used as adsorbents to recover valuable metals from leachates of mobile phone wastes. The mobile phone wastes (contactors) were collected and characterized. The valuable metals were extracted by thiourea leaching. The adsorption of valuable metals from leachates was studied according to the kinetic and equilibrium viewpoints. It was found that the contactors were composed by Au, Ni, Cu and Sn. The thiourea leaching provided extraction percentages of 68.6% for Au, 22.1% for Ni and 2.8% for Cu. Sn was not extracted. The leachate presented 17.5 mg L-1 of Au, 324.9 mg L-1 of Ni and 573.1 mg L-1 of Cu. The adsorption was fast, being the equilibrium attained within 120 min. The adsorption of Au, Ni and Cu onto CTN and AC followed the Langmuir model, while, the adsorption of these metals onto CTS, followed the Freundlich model. Removal percentages higher than 95% were obtained for all metals, depending of the type and amount of adsorbent. It was demonstrated that the adsorption onto chitin, chitosan and activated carbon can be an alternative to recover valuable metals from leachates of mobile phone wastes.


Subject(s)
Cell Phone , Electronic Waste , Metals/isolation & purification , Waste Management/methods , Adsorption , Charcoal/chemistry , Chitin/chemistry , Chitosan/chemistry , Hydrogen-Ion Concentration , Kinetics , Metals/chemistry , Microscopy, Electron, Scanning , Models, Chemical , Spectroscopy, Fourier Transform Infrared , Thiourea/chemistry , X-Ray Diffraction
13.
Chem Biol Drug Des ; 86(5): 969-78, 2015 Nov.
Article in English | MEDLINE | ID: mdl-25845502

ABSTRACT

Arginase is a glycosomal enzyme in Leishmania that is involved in polyamine and trypanothione biosynthesis. The central role of arginase in Leishmania (Leishmania) amazonensis was demonstrated by the generation of two mutants: one with an arginase lacking the glycosomal addressing signal and one in which the arginase-coding gene was knocked out. Both of these mutants exhibited decreased infectivity. Thus, arginase seems to be a potential drug target for Leishmania treatment. In an attempt to search for arginase inhibitors, 29 derivatives of the [1,2,4]triazolo[1,5-a]pyrimidine system were tested against Leishmania (Leishmania) amazonensis arginase in vitro. The [1,2,4]triazolo[1,5-a]pyrimidine scaffold containing R1  = CF3 exhibited greater activity against the arginase rather than when the substituent R1  = CH3 in the 2-position. The novel compound 2-(5-methyl-2-(trifluoromethyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl)hydrazinecarbothioamide (30) was the most potent, inhibiting arginase by a non-competitive mechanism, with the Ki and IC50 values for arginase inhibition estimated to be 17 ± 1 µm and 16.5 ± 0.5 µm, respectively. These results can guide the development of new drugs against leishmaniasis based on [1,2,4]triazolo[1,5-a]pyrimidine derivatives targeting the arginase enzyme.


Subject(s)
Arginase/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Leishmania/enzymology , Pyrimidines/chemistry , Pyrimidines/pharmacology , Thiourea/analogs & derivatives , Antiprotozoal Agents/chemistry , Antiprotozoal Agents/pharmacology , Arginase/metabolism , Cell Line , Drug Design , Humans , Leishmania/drug effects , Leishmaniasis/drug therapy , Thiourea/chemistry , Thiourea/pharmacology
14.
Acta Crystallogr C Struct Chem ; 70(Pt 11): 1064-8, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25370108

ABSTRACT

The title compound, C18H18N4OS2, was prepared by reaction of S,S-diethyl 2-thenoylimidodithiocarbonate with 5-amino-3-(4-methylphenyl)-1H-pyrazole using microwave irradiation under solvent-free conditions. In the molecule, the thiophene unit is disordered over two sets of atomic sites, with occupancies of 0.814 (4) and 0.186 (4), and the bonded distances provide evidence for polarization in the acylthiourea fragment and for aromatic type delocalization in the pyrazole ring. An intramolecular N-H···O hydrogen bond is present, forming an S(6) motif, and molecules are linked by N-H···O and N-H···N hydrogen bonds to form a ribbon in which centrosymmetric R2(2)(4) rings, built from N-H···O hydrogen bonds and flanked by inversion-related pairs of S(6) rings, alternate with centrosymmetric R2(2)(6) rings built from N-H···N hydrogen bonds.


Subject(s)
Thiophenes/chemistry , Thiourea/analogs & derivatives , Thiourea/chemistry , Crystallography, X-Ray , Hydrogen Bonding
15.
Comput Biol Med ; 43(10): 1334-40, 2013 Oct.
Article in English | MEDLINE | ID: mdl-24034724

ABSTRACT

Calpain-10 (CAPN10) is a cysteine protease that is activated by intracellular calcium (Ca(2+)) and known to be involved in diseases such as cancer, heart attack, and stroke. A role for the CAPN10 gene in diabetes mellitus type II was recently identified. Hyper activation of the enzyme initiates a series of destructive cycles that can cause irreversible damage to cells. The development of inhibitors may be useful as therapeutic agents for a number of calpainopathies. In this paper, we have used the homology modelling technique to determine the 3D structure of calpain-10 from Homo sapiens. The model of calpain-10 obtained by homology modelling suggests that its active site is conserved among family members and the main interactions are similar to those observed for µ-calpain. Structural analysis revealed that there are small differences in the charge distribution and molecular surface of the enzyme. These differences are probably less dependent on calcium for calpain-10 than they are for µ-calpain. In addition, the ion pair Cys(-)/His(+) formation was observed using of Molecular Dynamics (MD) simulations that were based upon hybrid quantum mechanical/molecular mechanical (QM/MM) approaches. Finally, the binding of the SNJ-1715 inhibitor to calpain-10 was investigated in order to further understand the mechanism of inhibition of calpain-10 by this inhibitor at the molecular level.


Subject(s)
Calpain/chemistry , Thiourea/analogs & derivatives , Amino Acid Sequence , Calpain/antagonists & inhibitors , Calpain/metabolism , Humans , Molecular Dynamics Simulation , Molecular Sequence Data , Reproducibility of Results , Sequence Alignment , Static Electricity , Thiourea/chemistry , Thiourea/metabolism , Thiourea/pharmacology
16.
Talanta ; 106: 293-7, 2013 Mar 15.
Article in English | MEDLINE | ID: mdl-23598130

ABSTRACT

In this paper, a method for the determination of mercury in phosphate fertilizers using slurry sampling and cold vapor atomic absorption spectrometry (CV QT AAS) is proposed. Because mercury (II) ions form strong complexes with phosphor compounds, the formation of metallic mercury vapor requires the presence of lanthanum chloride as a release agent. Thiourea increases the amount of mercury that is extracted from the solid sample to the liquid phase of the slurry. The method is established using two steps. First, the slurry is prepared using the sample, lanthanum chloride, hydrochloric acid solution and thiourea solution and is sonicated for 20 min. Afterward, mercury vapor is generated using an aliquot of the slurry in the presence of the hydrochloric acid solution and isoamylic alcohol with sodium tetrahydroborate solution as the reducing agent. The experimental conditions for slurry preparation were optimized using two-level full factorial design involving the factors: thiourea and lanthanum chloride concentrations and the duration of sonication. The method allows the determination of mercury by external calibration using aqueous standards with limits of detection and quantification of 2.4 and 8.2 µg kg(-1), respectively, and precision, expressed as relative standard deviation, of 6.36 and 5.81% for two phosphate fertilizer samples with mercury concentrations of 0.24 and 0.57 mg kg(-1), respectively. The accuracy was confirmed by the analysis of a certified reference material of phosphate fertilizer that was provided by the National Institute of Standards & Technology (NIST). The method was applied to determine mercury in six commercial samples of phosphate fertilizers. The mercury content varied from 33.97 to 209.28 µg kg(-1). These samples were also analyzed employing inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS results were consistent with the results from our proposed method.


Subject(s)
Fertilizers/analysis , Mercury/analysis , Organophosphates/chemistry , Spectrophotometry, Atomic/standards , Borohydrides/chemistry , Calibration , Cations, Divalent , Gases , Lanthanum/chemistry , Limit of Detection , Sonication , Spectrophotometry, Atomic/methods , Thiourea/chemistry , Volatilization
17.
Acta Crystallogr C ; 68(Pt 1): o19-22, 2012 Jan.
Article in English | MEDLINE | ID: mdl-22223282

ABSTRACT

In the crystal structure of the title compound, C(20)H(18)N(2)O(2)S, molecules are linked by bifurcated C-H···O hydrogen-bond interactions, giving rise to chains whose links are composed of alternating centrosymmetrically disposed pairs of molecules and characterized by R(2)(2)(10) and R(2)(2)(20) hydrogen-bonding motifs. Also, N-H···S hydrogen bonds form infinite zigzag chains along the [010] direction, which exhibit the C(4) motif. Hirshfeld surface and fingerprint plots were used to explore the intermolecular interactions in the crystal structure. This analysis confirms the important role of C-H···O hydrogen bonds in the molecular conformation and in the crystal structure, providing a potentially useful tool for a full understanding of the intermolecular interactions in acylthiourea derivatives.


Subject(s)
Furans/chemistry , Thiourea/analogs & derivatives , Crystallography, X-Ray , Hydrogen Bonding , Molecular Conformation , Molecular Probes , Molecular Structure , Thiourea/chemistry
18.
Contraception ; 85(1): 91-8, 2012 Jan.
Article in English | MEDLINE | ID: mdl-22067791

ABSTRACT

BACKGROUND: The copper intrauterine device is a contraceptive method that is based on the release of copper ions from a copper wire. Immediately after insertion, the dissolution of copper in the uterine fluid is markedly higher ("burst release") than that necessary for contraception action, leading to a variety of harmful effects. STUDY DESIGN: Pretreatments with organic compounds [thiourea (TU) and purine (PU), 10(-4)-10(-2) M concentration range, 1- and 3-h immersion times] were tested. The dissolution of copper with and without pretreatments in TU and PU solutions was analyzed by conventional electrochemical techniques and surface analysis. RESULTS: Pretreatments in PU solutions reduced the initial corrosion rate of copper in simulated uterine solutions, with inhibitory efficiencies that depend on the PU concentration and on the immersion time assayed. Inhibitory efficiency values higher than 98% for pretreatments with ≥10(-3) M PU were found. Conversely, after TU pretreatments, a high copper release was measured. CONCLUSIONS: It was concluded that 10(-3) M PU pretreatment is a promising strategy able to reduce the "burst release" of copper and to ensure contraceptive action.


Subject(s)
Copper/chemistry , Intrauterine Devices, Copper/adverse effects , Purines/chemistry , Thiourea/chemistry , Copper/analysis , Corrosion , Electrochemical Techniques
19.
Biol Trace Elem Res ; 140(3): 262-71, 2011 Jun.
Article in English | MEDLINE | ID: mdl-20419397

ABSTRACT

A simplified thiourea-based chromatography method, originally developed for methyl and inorganic mercury, was adapted to separate methylmercury (MeHg), ethylmercury (EtHg), and inorganic mercury (Hg(II)) in infants' hair. Samples were weighed and leached with an acidic thiourea solution. Leachates were concentrated on a polymeric resin prior to analysis by Hg-thiourea liquid chromatography/cold vapor atomic fluorescence spectrometry. All but one sample showed small amounts of EtHg, and four of the six analyzed samples had proportionally higher Hg(II) as a percent of total Hg. Breastfed infants from riverine Amazonian communities are exposed to mercury in breast milk (from high levels of maternal sources that include both fish consumption and dental amalgam) and to EtHg in vaccines (from thimerosal). The method proved sensitive enough to detect and quantify acute EtHg exposure after shots of thimerosal-containing vaccines. Based on work with MeHg and Hg(II), estimated detection limits for this method are 0.050, 0.10, and 0.10 ng g⁻¹ for MeHg, Hg(II), and EtHg, respectively, for a 20-mg sample. Specific limits depend on the amount of sample extracted and the amount of extract injected.


Subject(s)
Ethylmercury Compounds/analysis , Hair/chemistry , Mercury/analysis , Methylmercury Compounds/analysis , Thimerosal/chemistry , Vaccines/adverse effects , Vaccines/chemistry , Child, Preschool , Humans , Thiourea/chemistry
20.
J Chem Inf Model ; 51(1): 130-8, 2011 Jan 24.
Article in English | MEDLINE | ID: mdl-21133347

ABSTRACT

The binding of several classes of nonnucleoside reverse transcriptase inhibitors (NNRTIs) to wild-type (wtRT) and K103N mutant (mRT) human immunodeficiency virus type 1 (HIV-1) reverse transcriptase is studied by molecular dynamics and energy decomposition techniques. The imidoylthiourea (ITU), diaryltriazine (DATA), and diarylpyrimidine (DAPY) NNRTIs studied maintain the hydrogen bond with Lys101 during the 3 ns molecular dynamics trajectories. When bound to mRT, all the DAPYs studied establish hydrogen bonds with Glu138; among these, those of the potent inhibitors TMC120 and TMC125 are water-mediated. The molecular interactions of the NNRTIs in the binding pocket are correlated to the drugs' potency. Quantitative free energy analyses show a linear relationship between the van der Waals energetic component and the potency against wtRT. The molecular basis of the interaction between NNRTIs and RT presented here provide quantitative approaches for the design of novel effective anti-HIV drugs.


Subject(s)
Drug Design , HIV Reverse Transcriptase/antagonists & inhibitors , HIV-1/enzymology , Reverse Transcriptase Inhibitors/pharmacology , Anti-HIV Agents/chemistry , Anti-HIV Agents/metabolism , Anti-HIV Agents/pharmacology , Crystallography, X-Ray , HIV Reverse Transcriptase/chemistry , HIV Reverse Transcriptase/genetics , HIV Reverse Transcriptase/metabolism , HIV-1/drug effects , Inhibitory Concentration 50 , Molecular Dynamics Simulation , Mutation , Nevirapine/chemistry , Nevirapine/metabolism , Nevirapine/pharmacology , Protein Conformation , Reverse Transcriptase Inhibitors/chemistry , Reverse Transcriptase Inhibitors/metabolism , Solvents/chemistry , Thermodynamics , Thiourea/analogs & derivatives , Thiourea/chemistry , Thiourea/metabolism , Thiourea/pharmacology
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