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PubMed1986

Synthesis and antimicrobial activities of N4-(2-acetoxyethoxymethyl)thiosemicarbazones and N3-(2-acetoxyethoxymethyl)thioureas.

A series of thiosemicarbazones and thioureas having an open-chain analogue of the ribosyl group, the 2-acetoxyethoxymethyl moiety, has been synthesized. Significant growth inhibitory activity versus gram-positive and gram-negative organisms, a yeast, and a mold has been found with the 2-acetoxyethoxymethyl derivatives of N-alkyl-, aryl-, and heteroaryl-thiosemicarbazones and thioureas. The molecules may function as inhibitors of ribonucleotide reductase or in utilization of the carbamyl group in pyrimidine biosynthesis.

Anti-Bacterial Agents↗
PubMed1998

The urease-catalyzed hydrolysis of thiourea and thioacetamide.

Jack bean urease catalyzes the hydrolysis of thiourea with a second-order rate constant (kcat/Km) of 1.6 (+/- 0.2) x 10(-3) M-1 S-1 at pH7, 25 degrees C. This value is lower than that for urea by a factor of 3 x 10(8). The corresponding substitution of S for O in acetamide reduces the kcat/Km value by only a factor of 33. This greater reactivity of the oxo compounds than of the corresponding thiono compounds, and the tighter binding of urea (Ks = 2.9 mM) than of either the guanidinium ion (Ki = 30 mM) or thiourea (Ki = 70 mM), suggests that the substrate chalcogen (S or O) is more likely to be stabilized in the transition state by coordination to the enzyme via a neutral hydrogen-bond donor (i.e., Brønsted acid catalysis) than by coordination via one of the active-site nickel ions (i.e., Lewis acid catalysis).

Fabaceae↗
PubMed2026

UVB photoprotection by thiourea and (thio)semicarbazone derivatives: cellular and molecular evidence.

BACKGROUND: Ultraviolet B (UVB) radiation is a major environmental stressor that contributes to oxidative stress, inflammation, DNA damage, and ultimately an increased risk of skin carcinogenesis. The development of safer, multifaceted UV filters with improved photostability and bioprotective properties remains an important research priority. Here, alkyl chain-conjugated thiourea (I-XIX) and aryl-linked (thio)semicarbazone (XX-XXV) derivatives have been systematically assessed for their photoprotective potential against UVB-induced cellular damage. METHODS: The UV absorption properties, molar absorptivity, and photostability of the test compounds were assessed through spectroscopic studies. Cytotoxicity, effective concentrations, and bioprotective effects of the compounds were evaluated using in vitro cellular methods. RESULTS: Several compounds exhibited robust UVB absorption with high molar absorptivity, particularly semicarbazone derivatives, while displaying minimal cytotoxicity to normal human dermal fibroblasts. Among the evaluated compounds, ten compounds were found to be more photostable than benzophenone (reference compound). Selected compounds significantly reduced UVB-induced intracellular reactive oxygen species and nitric oxide production, signifying effective attenuation of oxidative and nitrosative stress. In addition, compounds IV, XXI, and XXIII alleviated UVB-induced inflammatory cascades by diminishing Interleukin-1 beta (IL-1β) and Tumor Necrosis Factor alpha (TNF-α) levels. Therefore, these compounds also protected fibroblast morphology. Moreover, the same compounds protected from DNA damage by preventing UVB-induced genomic DNA fragmentation and formation of cyclobutane pyrimidine dimers. In particular, compound XXIII displayed selective UVB absorption, better photostability, low cytotoxicity, and moderate biological photoprotection (SPF 16). CONCLUSION: Together, the results suggest that thiourea and (thio)semicarbazone derivatives, notably compound XXIII, represent promising photoprotective scaffolds requiring further formulation, in vivo, permeability, phototoxicity, and safety studies to validate their potential as UV-filtering agents.

Humans↗
PubMed1979

Azethoxyl nitroxide spin labels. ESR studies involving thiourea crystals, model membrane systems and chromatophores, and chemical reduction with ascorbate and dithiothreitol.

Trans- and cis-azethoxyl nitroxides 1, 2, 3 and 4 can be trapped in the cavities of thiourea crystals. The presence of a single gauche conformation on either side of the pyrrolidine ring within the crystals was indicated by the ESR spectra. Rotation about the long molecular axis then corresponds approximately to y-axis motion of the nitroxide moiety. Proxyl nitroxides in which the nitroxide group is located on the penultimate carbon of long chain lipids can also be trapped and were shown to adopt the azethoxyl conformation in the thiourea crystals. The measured deltaA values (A parallel to - A perpendicular) of oriented egg lecithin multilayers containing trans- and cis-azethoxyl nitroxides 1 and 2 were quite small, consistent with the unique orientation of the nitroxide principal axes with respect to the long axis of the molecule. The deltaA values for a series of lipids bearing a label near the terminus of the chain were very similar to that of 1, showing that the azethoxyl conformation is likely the predominant one in these labels in orienting systems. Computer simulations of the ESR spectra of 1 and 2 in egg lecithin vesicles provided values for molecular orientation and motion parameters consistent with those expected from a consideration of molecular models in the extended (all trans) conformation. Azethoxyl nitroxides have also proven useful in the investigation of motion restricted (boundary) lipid in a lipid-protein system. Thus, the values (69 +/- 10%) for the amount of boundary lipid in the chromatophore membranes from Rhodopseudomonas sphaeroides as determined using trans- 2 and cis- 2 are in good agreement with values using 16-doxylstearic acid (64 +/- 3%). The fact that all three labels show about the same fraction of boundary lipid in this system indicates that the lipid binding sites are relatively insensitive to the geometry of the lipid chain. Also, both 1 and 2 appear to be able to detect a third lipid environment not seen with the doxyl fatty acid. The apparent fluidity of this component lies between that of boundary and bilayer lipid. The unique orientation of the nitroxide principal axes with respect to the long molecular axis in azethoxyl nitroxides 1 and 2 allows detection of hindrance to rotation about the long molecular axis, in contrast to the analogous doxyl and proxyl fatty acids. Comparative reduction studies using ascorbate and dithiothreitol indicate that azethoxyl nitroxides are slightly more resistant toward reduction than proxyl nitroxides and much more resistant than doxyl nitroxides.

Ascorbic Acid↗
PubMed1983

Determination of acetaldehyde in human blood using thiourea to inhibit ethanol interference.

Determination of acetaldehyde in human blood by the semicarbazide method has been studied. An artefactual production of acetaldehyde from ethanol in blood and plasma of about 20 mumol/l was observed at concentrations of ethanol of about 60 mmol/l. This artefact was reduced to less than 1 mumol/l after addition of thiourea. The presumably non-enzymatic production of acetaldehyde from ethanol was demonstrated by the release of 3H from (1R)-[3H]ethanol added to the blood immediately after sampling. The results demonstrate that oxidation of ethanol is the major cause of the artefactual acetaldehyde formation. In human volunteers, metabolising ethanol, very low concentrations of acetaldehyde were found by the modified method, which includes thiourea.

Acetaldehyde↗
PubMed1983

Activation of xanthine dehydrogenase during the prenatal period through L-thyroxine, thiourea and cycloheximide.

Xanthine dehydrogenase activity in the liver of embryonic chicks has been shown to be inducible by L-thyroxine, thiourea, and cycloheximide. Results reported here indicate different mechanisms underlying the activation through L-thyroxine on the one hand, and through thiourea and cycloheximide on the other. Using hepatocyte suspension and homogenized liver, it has been shown that prenatal activation of xanthine dehydrogenase results in increased rate of uric acid formation from nucleic acids and purine derivatives, but not from amino acids.

Animals↗
PubMed1983

Motility pattern and lung respiration of embryonic chicks under the influence of L-thyroxine and thiourea.

Pressure changes in the air cell and at the egg shell have been used to monitor respiratory and somatic movements of embryonic chicks. During the prehatching period a phase of reduced activity is observed. Pulmonary respiration is initiated during this phase. Exogenous L-thyroxine exerts an accelerating effect on the hatching process and on the onset of the phase of reduced motility and of lung respiration. In thiourea-treated embryos the opposite effects on the hatching process and on the motility and respiration pattern are registered. When, however, the egg shell above the air cell was sealed with glue, times of hatching and of the beginning of lung respiration were similar to those of controls, although pipping the egg shell occurred earlier than normal. It is suggested that the effects of L-thyroxine and thiourea on the hatching process are caused by a premature or delayed onset, respectively, of pulmonary respiration.

Animals↗
PubMed1984

Lung respiration, somatic activity and gas metabolism in embryonic chicks prevented from hatching by thiourea.

Treating chick embryos with high doses of thiourea (32.8 mumol) on day 17 of incubation resulted in prevention of hatching and of active breathing. Furthermore, thiourea also prevented the increase of O2 consumption and the marked increase of somatic activity associated with the final hatching act. These findings provide evidence for the importance of active breathing in the prenatal period to initiate pipping and hatching of the avian embryo.

Animals↗
PubMed2005

Thiourea-based non-nucleoside inhibitors of HIV reverse transcriptase as bifunctional organocatalysts in the asymmetric Strecker synthesis.

The potential of novel and known pyridyl thiourea derivatives (non-nucleoside inhibitors (NNI) of HIV reverse transcriptase) as bifunctional organic catalysts in the asymmetric Strecker synthesis was investigated. It was shown that incorporation of the imidazolyl moiety in place of a pyridyl group results in a new thiourea derivative that displays a much higher catalytic activity.

Catalysis↗
PubMed2005

Synthesis, cytotoxicity, and DNA-topoisomerase inhibitory activity of new asymmetric ureas and thioureas.

A new series of N-3,3-diphenylpropyl-N-(p-X-benzyl)-N'-phenylureas (5a-g) and thioureas (6a-g) were synthesized by the reaction of secondary amines and phenyl isocyanate or isothiocyanate. The cytotoxic effects of the urea and thiourea derivatives were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay against Ehrlich carcinoma and K562 human leukemia cells. Moreover, the activity of compounds in the inhibition of DNA topoisomerases I and II-alpha was tested. The results indicated that the compounds presented important and promising antiproliferative action.

Animals↗
PubMed2004

Identification of 4-piperazin-1-yl-quinazoline template based aryl and benzyl thioureas as potent, selective, and orally bioavailable inhibitors of platelet-derived growth factor (PDGF) receptor.

4-[4-(N-Substituted-thio-carbamoyl)-1-piperazinyl]-6-methoxy-7-alkoxyamino-quinazoline derivatives such as 14 (CT53986) have been identified to be potent and selective inhibitors of the phosphorylation of PDGFR. SAR-investigations are described in the arylamine segment, C-7 appendage, and the thiourea moiety. Bioisosteres of thiourea (cyanoguanidine), and of quinazoline (quinoline-3-carbonitrile) were synthesized and are compared for their in vitro inhibitory activity. PK profiles of the optimized compounds in rat, dog, and cynomolgus monkey are described.

Administration, Oral↗
PubMed2006

Synthesis and biological evaluation of 1beta-methylcarbapenems having cyclic thiourea moieties and their related compounds.

The synthesis of a new series of 1beta-methylcarbapenems having cyclic thiourea moieties is described. Their in vitro antibacterial activities against both Gram-positive and Gram-negative bacteria were tested and the effect of substituent on the pyrrolidine ring was investigated. A particular compound (IIId) having piperazine thiourea moiety showed the most potent antibacterial activity.

Anti-Bacterial Agents↗
PubMed2005

The intercalation to DNA of bipyridyl complexes of platinum(II) with thioureas.

The non-covalent interaction of the complexes [Pt(bpy)(R,R'NCSNR'',R''')(2)]Cl(2) (bpy=2,2'-bipyridine; R=R'=R''=R'''=H; R=Me, R'=R''=R'''=H; R=n-Bu, R'=R''=R'''=H; R=p-tolyl, R'=R''=R'''=H; R=Et, R'=H, R''=Et, R'''=H) with calf thymus DNA has been studied at pH 7 and 25 degrees C. The processes give rise to: (i) reversible bathochromic shifts and strong hypochromicity of the absorption bands of the complexes, (ii) induced circular dichroism and (iii) an increase both in the melting temperature and viscosity of the DNA comparable to that observed for other well known metallointercalators. The binding constants, K(B), have been determined spectrophotometrically using the McGhee von Hippel equation. Plot of logK(B) vs -log[Na(+)] for the complex with unsubstituted thiourea gives a straight line with a slope value close to that expected for a dicationic intercalator. The binding affinity of the various complexes for DNA is independent of the thiourea nature; this suggests that the intercalation occurs through stacking of the bpy moiety while the ancillary ligands lie outside the nucleobases far away from the sugar phosphate backbone. The data show also that the electronic effects of the ligand substituents are not transmitted to the intercalating unit.

2,2'-Dipyridyl↗
PubMed2006

Fluoride-selective colorimetric sensor based on thiourea binding site and anthraquinone reporter.

A structurally simple colorimetric sensor, N-4-nitrobenzene-N'-1'-anthraquinone-thiourea (1), for anions was synthesized and characterized by (1)H NMR, ESI mass and IR methods. In acetonitrile, the addition of F(-) changed 1 solution from colorless to yellow. In the presence of other anions such as CH(3)CO(2)(-), H(2)PO(4)(-), HSO(4)(-) and Cl(-), however, the absorption spectrum of 1 was slightly red shifted with no obvious color changes observed. The association constants of anionic complexes followed the order of F(-)>>CH(3)CO(2)(-)>H(2)PO(4)(-)>HSO(4)(-)>Cl(-)>Br(-), which was different from the order of anion basicity. AM1 calculation results indicated that the most stable configuration of 1 existed in the Z-E-conformation with a six-membered ring via intramolecular hydrogen bond. This made thiourea moiety of 1 in an unfavorable conformation to bond with oxygen-anionic substrates such as CH(3)CO(2)(-) and H(2)PO(4)(-), thus leading to a high selectivity and sensitivity for the detection of F(-).

Anions↗
PubMed2002

Thiourea toxicity in mouse C3H/10T1/2 cells expressing human flavin-dependent monooxygenase 3.

Human flavin-dependent monooxygenase (FMO) isoforms 1 and 3 were expressed by retroviral gene transfer in mouse C3H/10T1/2 cells. FMO function was determined by the sulfoxidation of p-tolylmethylsulfide (TMS). Enzyme activity ranged from 4 to 30 nmol p-tolylmethylsulfoxide (TMSO)/30 min/mg cell protein for FMO 3 clones; for FMO 1 clones, the range was 1-6 nmol TMSO/30 min/mg. Cytotoxicity in these clones after exposure to thiocarbamate compounds was assessed by clonogenic assay. Thiourea (TU), phenylthiourea (PTU), and alpha-naphthylthiourea (ANTU) were toxic to FMO 3 cells but not to parental and FMO 1 clones; 50% toxicity was attained at 1x10(-4) M TU, 5x10(-6) M PTU, and 1x10(-6) M ANTU. Toxicity was observed after a minimum exposure time of 6 hr. Parental cells were resistant to toxicity for exposure times spanning the entire clonogenic assay period (10 days). Ethylene thiourea (ETU) was not toxic to FMO 3 cells, but preincubation with 1x10(-3) M ETU blocked TU toxicity. Reducing GSH levels by preincubation with 1x10(-5) M buthionine sulfoxime (BSO) increased TU sensitivity in FMO 3 cells from 1x10(-4) to 1x10(-6) M to achieve 50% toxicity. BSO also increased the sensitivity of "low expressor" FMO 3 clones to TU, but did not alter the refractoriness of either parental or FMO 1 expressing cells to TU. N-Acetylcysteine afforded modest protection to TU toxicity by shifting 50% cytotoxicity for TU from 5x10(-5) to 1x10(-3) M. TU mutagenicity was assayed by the development of ouabain resistance in parental and FMO 3 C3H/10T1/2 cells. Exposure to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, direct acting mutagen) and TU was executed with and without prior sensitization with BSO. The mutation frequency for MNNG was 76/1x10(6) surviving cells, whereas no mutants were observed for TU-exposed cultures. The results of this study show that, in isolation, the major human hepatic form of FMO is capable of promoting thiocarbamate toxicity. Consistent with the known reactivity of thiocarbamate intermediates with GSH, treatments that alter GSH levels also altered toxicity in either the protective or sensitizing direction. These cell lines expressing variable levels of FMO 3 and TU sensitivity should prove useful as in vitro systems for dissecting the thiocarbamate toxicity pathway.

Animals↗
PubMed2002

Synthesis and antituberculosis activity of new N-phenyl-N'-[4-(5-alkyl/arylamino-1,3,4-thiadiazole-2-yl)phenyl]thioureas.

In this study, eight original N-phenyl-N'-[4-(5-alkyl/arylamino-1,3,4-thiadiazole-2-yl)phenyl]thiourea derivatives were synthesized and tested for antituberculosis activity. Antituberculosis activities of the synthesized compounds were screened in vitro using BACTEC 460 Radiometric System against Mycobacterium tuberculosis H37Rv at 6.25 microg/ml. The highest inhibition observed with the synthesized compounds is 67% for N-phenyl-N'-[4-(5-cyclohexylamino-1,3,4-thiadiazole-2-yl)phenyl]thiourea.

Antitubercular Agents↗
PubMed1997

Thiourea and dimethylthiourea inhibit peroxynitrite-dependent damage: nonspecificity as hydroxyl radical scavengers.

Thiourea and, more recently, dimethylthiourea, have been used as hydroxyl radical (OH.) scavengers in experiments both in vitro and in vivo. We show that both compounds can inhibit nitration of the amino acid tyrosine on addition of peroxynitrite, and also the inactivation of alpha1-antiproteinase by peroxynitrite. Hence, protective effects of (dimethyl) thiourea could be due to inhibition of peroxynitrite-dependent damage as well as to OH. scavenging, and these compounds must not be regarded as specific OH. scavengers.

Enzyme Inhibitors↗
PubMed2000

Stereochemistry of halopyridyl and thiazolyl thiourea compounds is a major determinant of their potency as nonnucleoside inhibitors of HIV-1 reverse transcriptase.

Chiral derivatives of two cyclohexylethyl halopyridyl thiourea compounds (HI-509 and HI-510), two alpha-methyl benzyl halopyridyl compounds (HI-511 and HI-512), and a cyclohexyl ethyl thiazolyl thiourea compound (HI-513) were synthesized as nonnucleoside inhibitors (NNI) of human immunodeficiency virus (HIV) reverse transcriptase (RT). The R stereoisomers of all five compounds inhibited the recombinant RT in vitro with 100-fold lower IC50 values. HI-509R, HI-510R, HI-511R, HI-512R and HI-513R were active anti-HIV agents and inhibited HIV-1 replication in human peripheral blood mononuclear cells at nanomolar concentrations, whereas their enantiomers were inactive. Each of these five compounds was also active against NNI-resistant HIV-1 strains, with HI-511R being the most active agent. When tested against the NNI-resistant HIV-1 strain A17 with a Y181C mutation in RT, HI-511R was found to be 10,000-times more active than nevirapine, 5000-times more active than delavirdine, and 50-times more active than trovirdine. HI-511 R inhibited the HIV-strain A17 variant, containing RT mutations Y181C plus K103N, with an IC50 value of 2.7 microM, whereas the IC50 values of nevirapine, delavirdine, and trovirdine against this highly NNI-resistant HIV-1 strain were >100 microM.

Anti-HIV Agents↗