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PubMed2005

Uptake-toxicity relationships of a series of N-substituted N'-(4-imidazole-ethyl)thiourea in precision-cut rat liver slices.

A previous study showed that the cytotoxicity of a series of N-p-phenyl-substituted N'-(4-imidazole-ethyl)thiourea in precision-cut rat liver slices increased with increasing electron-withdrawing capacity of the p-substituent and may be related to the Vmax/Km values of bioactivation of the thiourea-moiety by hepatic flavin-containing monooxygenases (FMOs). However, differences in the uptake of xenobiotics into precision-cut liver slices can also have consequences for the rates of metabolism of xenobiotics. In the present study, therefore, we investigated the rate and nature of uptake of 9 N-substituted N'-(4-imidazole-ethyl)thiourea into precision-cut rat liver slices. It was found that a five-fold difference exists among a series of N-substituted N'-(4-imidazole-ethyl)thiourea both in the initial rate of uptake and in the steady-state levels ultimately achieved in the precision-cut rat liver slices. It appeared that the most cytotoxic compounds were also the most readily absorbed compounds. The concentration-dependent initial rate of uptake could be described by a carrier-mediated saturable component and a non-saturable component. At cytotoxic concentrations, the non-saturable component accounted for more than 95% of the total uptake. From this study, it is concluded that differences in rate of uptake of thiourea-containing compounds may be a contributing factor to the differences in bioactivation by FMOs as the basis of the structure-toxicity relationships observed in precision-cut rat liver slices.

Animals↗
PubMed1996

Thiourea as a melanoma targeting agent.

It has previously been shown that various thiourea derivatives are incorporated into nascent melanin, and a few of these substances, e.g. 2-thiouracil and its radioiodinated analogue, have been used for selective targeting of melanotic melanoma. Possible localization of thiourea itself in melanoma, however, has not been investigated so far. We have therefore performed the present autoradiographic and impulse counting study on the disposition of 14C-thiourea in mice transplanted with B16 melanoma. The results demonstrated a pronounced, but partly heterogeneous, uptake of radioactivity in the melanoma tissue, with the highest concentration 4 h after the injection. Four days after the administration of a single dose, the retention of label was still high in certain tumoral areas. The lung was the only normal tissue with a similarly high uptake of radioactivity. Additional experiments in vitro showed that the incorporation of thiourea into melanin was dose-dependent. The binding to performed melanin was found to be low, which strongly indicates that the incorporation of thiourea into melanin mainly is due to interaction with intermediates of the melanin synthetic pathway.

Animals↗
PubMed1976

Permeability of individual human erythrocytes to thiourea.

The osmotic swelling to haemolysis of individual red blood cells by isosmotic thiourea has been studied using microcine photography. 2. Crenation occurs immediately upon addition of isosmotic thiourea. The cell becomes a crenated sphere without volume decrease. 3. Subsequently, the cell volume increases linearly with time with maximum swelling occurring at about 102 sec which is 81% of the total haemolysis time. 4. At maximum swelling, the cell volume is 92% greater than the initial cell volume. This volume increase is about double that measured with other permeating substances. 5. The much larger maximum volume implies that thiourea increases the area of the cell membrane. This increase varies from 0 to 75% for individual cells, with a mean of 22%. 6. Membrane expansion varies inversely as the initial cell membrane area and cell volume (r=0-790). 7. Using the increased surface area, increased maximum volume and the swelling time, the mean permeability is calculated to be 5-52 X 10(-7) cm/sec (S.D. of mean=+/-1-19 X 10(-7) cm/sec). The distribution of permeabilities represents a normal distribution. 8. The pre-lytic potassium loss ranged from 0 to 36% with a mean value of 16-5%. This is consistent with values reported in the literature for slow haemolysis. As with other permeants the distribution is skewed towards lower values. 9. Membrane permeability of individual cells varies with the amount of membrane expansion observed. Coefficient of correlation between permeability and expansion index is 0-674. 10. There is no correlation between permeability and the reciprocal of the haemolysis time (r=-0-035). The correlation between permeability and the reciprocal of the swelling time is also poor (r=0-303), probably owing to the variability in membrane expansion by thiourea in individual cells. 11. As has been shown previously for faster permeants, the permeability coefficient cannot be calculated from the haemolysis time. Because thiourea alters the membrane area and the haemolytic volume, the coefficient cannot be calculated from the swelling time unless the changes in the membrane area are also taken into account.

Cell Membrane↗
PubMed1990

Concentration dependence of urea and thiourea transport in rat inner medullary collecting duct.

The vasopressin-dependent urea permeability of the rat terminal inner medullary collecting duct (IMCD) is much greater than can be explained by lipid-phase permeation or paracellular diffusion, suggesting the presence of vasopressin-stimulated facilitated transport pathway. We used the isolated perfused tubule technique to test whether the urea transport pathway exhibits saturation characteristics consistent with a facilitated pathway. When the luminal urea concentration was varied between 0 and 800 mM (no urea in peritubular bath), the relationship between the urea flux and the luminal concentration was linear with a y-axis intercept that was not significantly different from zero, indicating an absence of saturation in this concentration range. Higher concentrations of urea could not be tested due to technical limitations. However, when thiourea (a urea analogue that shares the urea transport pathway with urea) was substituted for urea in similar experiments, the apparent thiourea permeability fell with increasing thiourea concentration in the range 10-200 mM, indicative of saturation of the urea-thiourea transporter. When the urea concentration was varied in both bath and lumen, the lumen-to-bath urea flux approached a limiting value at 400-500 mM urea, consistent with saturation of the transporter. However, nonspecific inhibition of urea transport by bath urea could not be ruled out in those experiments. We conclude that the urea and thiourea transport pathway in the terminal IMCD exhibits saturation characteristics. However, the urea concentration required to saturate the pathway is apparently high, at least 400-500 mM in one set of experiments and probably greater than 800 mM in another.

Animals↗
PubMed1984

Thiourea causes endothelial cells in tissue culture to produce neutrophil chemoattractant activity.

We describe neutrophil chemoattractant activity that is produced by cultured bovine aortic and pulmonary arterial endothelial cells when incubated with thiourea, a substance that causes increased permeability pulmonary edema in animals. The chemoattractant activity was present in culture supernates and cell lysates of endothelial cells incubated with thiourea but was not present in untreated cells. Production of chemoattractant activity was not associated with cell death; viable cell counts and cell homogenate angiotensin converting enzyme levels were not affected, and Cr release was only slightly elevated after incubation with thiourea. At least 1.5 h of incubation with 0.5 mM thiourea was necessary for generation of neutrophil chemoattractant activity. Culture supernates from pulmonary vascular smooth muscle cells and lung fibroblasts did not show increased neutrophil chemoattractant activity after incubation with thiourea. The chemoattractant had both chemokinetic and chemotactic properties, was heat stable, and was extractable into organic solvents. Meclofenamate, a cyclooxygenase inhibitor, minimally inhibited chemoattractant production, whereas 5,8,11,14-eicosatetraynoic acid (ETYA), an inhibitor of both cyclooxygenase and lipoxygenase, completely abolished generation of chemoattractant activity, suggesting that the activity could be a product of arachidonic acid metabolism. These results demonstrate that endothelial cells can produce a substance(s) with neutrophil chemotactic activity. Production of neutrophil chemoattractant activity by endothelial cells could be important in polymorphonuclear leukocyte accumulation at injured vascular sites.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1973

Inhibition of vasopressin-stimulated urea transport across the toad bladder by thiourea.

The mammalian antidiuretic hormone, 8-arginine-vasopressin, was found to increase net mucosal-to-serosal urea flux across the isolated toad urinary bladder 13-fold. This urea flux was accompanied by a 24-fold increase in solute-linked water movement across the membrane. Net urea flux and urea-linked volume flux were inhibited by 50% or more when thiourea was added to the mucosal medium at concentrations equal to those of urea. In contrast, thiourea did not inhibit osmotic water flux across the bladder in the presence of vasopressin. These observations are consistant with the view that thiourea and urea compete for a common site on a membrane carrier molecule. When bladders were exposed to vasopressin on the serosa and subsequently fixed with 1% glutaraldehyde on the mucosa, they were found to retain 74% of their prefixation permeability to urea. Net urea flux across these fixed bladders (in the absence of vasopressin) was markedly inhibited by thiourea, whereas osmotic water flux was not inhibited. These studies suggest that vasopressin induces the formation of "urea-channels" in the membrane that can be preserved by glutaraldehyde and blocked by thiourea.

Animals↗
PubMed1981

Protection by sodium thiosulfate and thiourea against lethal toxicity of cis-diamminedichloroplatinum (II) in bacteria and mice.

The protective effect of sodium thiosulfate and thiourea on the lethal toxicity of the antitumor drug, cis-diamminedichloroplatinum (II) (cis-DDP), was investigated in bacteria and mice. Initially, the agents capable of antagonizing bactericidal activity of cis-DDP were screened using WP2 uvra, a strain of E. coli sensitive to this drug. Of the ten sulfur-containing compounds tested, thiourea and sodium thiosulfate exhibited potent protecting effects against cis-DDP cytotoxicity in bacteria. Propylthiouracil and methimazole showed intermediate levels of such protection, but the other 6 compounds had little or no protective effects. Thiourea and sodium thiosulfate were then subjected to the acute lethal toxicity test in mice to assess their protective activity in vivo. We found that cis-DDP i.v. lethality against mice can be blocked almost completely by excess amounts of thiourea or sodium thiosulfate. Thiourea protected against cis-DDP toxicity with a narrow range among the effective doses, while sodium thiosulfate was protective with a remarkably wide range of effective doses. The effectiveness of sodium thiosulfate was also indicated in experiments in which the LD50 dose of cis-DDP (16 mg/kg) i.p. increased over the level of greater than 200 mg/kg with concomitant administration of sodium thiosulfate i.p.

Animals↗
PubMed2001

[Effect of acryl thiourea on liver pathologic changes in mice infected with Schistosoma japonicum].

OBJECTIVE: To observe the effect of acryl thiourea, an inhibitor of phenol oxidase, on pathological changes in the liver of mice infected with Schistosoma japonicum. METHODS: From day 22 to day 42 postinfection with cercariae, the mice of the acryl thiourea group were each injected i.p. with acryl thiourea at a dose of 300 mg/kg every other day. The mice were killed on the 42nd day postinfection to observe the pathological changes in the liver. RESULTS: Compared to the infected control group, the liver tissue of the acryl thiourea group showed scattered foci of inflammatory cell infiltration, the mean diameter and area of the foci were significantly reduced (P < 0.01), and there were no eggs in the center of the foci except for some granules. CONCLUSION: After i.p. injections of acryl thiourea, no typical egg granuloma was found in the liver of infected mice. This was possibly due to the inhibition of schistosome phenol oxidase activity and so the female adult schistosomes could not produce normal eggs.

Animals↗
PubMed1979

Gas-liquid chromatographic determination of thiourea in citrus peels.

A gas-liquid chromatographic (GLC) method was developed for the detection and determination of thiourea in citrus peels. After the peel is extracted with ethyl ether, the ether extract is adsorbed on sodium sulfate together with water. Thiourea is recoverd from both the sodium sulfate and the peel residue with ethyl acetate-acetone(2+1). The extracted mixture is cleaned on an alumina column, the eluate is concentrated under vacuum, and thiourea is extracted from the concentrate with sodium carbonate solution. GLC was carried out on the prepared benzoyl derivative of thiourea. The average recoveries of thiourea from lemon peel were 85.3, 93.1, and 97.6% at the fortification levels of 1, 10, and 100 ppm, respectively. The detection limit was low as 0.08 ppm.

Chromatography, Gas↗
PubMed2002

Two thiourea-containing gold(I) complexes.

The crystal structures of two salts of bis(thiourea)gold(I) complexes, namely bis(thiourea-kappaS)gold(I) chloride, [Au(CH(4)N(2)S)(2)]Cl, (I), and bis[bis(thiourea-kappaS)gold(I)] sulfate, [Au(CH(4)N(2)S)(2)](2)SO(4), (II), have been determined. The chloride salt, (I), is isomorphous with the corresponding bromide salt, although there are differences in the bonding. The Au(I) ion is located on an inversion centre and coordinated by two symmetry-related thiourea ligands through the lone pairs on their S atoms [Au-S 2.278 (2) A and Au-S-C 105.3 (2) degrees ]. The sulfate salt, (II), crystallizes with four independent [Au(CH(4)N(2)S)(2)]+ cations per asymmetric unit, all with nearly linear S-Au-S bonding. The cations in (II) have similar conformations to that found for (I). The Au-S distances range from 2.276 (3) to 2.287 (3) A and the Au-S-C angles from 173.5 (1) to 177.7 (1) degrees. These data are relevant in interpreting different electrochemical processes where gold-thiourea species are formed.

Journal Article↗
PubMed2000

X-ray diffraction study of copper(I) thiourea complexes formed in sulfate-containing acid solutions

The formation of three different copper(I) thiourea complexes in sulfate-containing acid solutions was observed. The ratio between Cu(I) and thiourea (tu) in these complexes depends on the amount of thiourea and copper sulfate in the solution. The crystal and molecular structure of a new complex, [Cu(2)(tu)(6)](SO(4)).H(2)O, was determined, and the formation and structures of [Cu(2)(tu)(5)](SO(4)).3H(2)O and [Cu(4)(tu)(7)](SO(4))(2).H(2)O were confirmed. The compound [Cu(2)(tu)(6)](SO(4)).H(2)O crystallizes in the P1; space group, with a = 11.079 (2), b = 11.262 (1), c = 12.195 (2) A, alpha = 64.84 (1), beta = 76.12 (1), gamma = 66.06 (1) degrees, and Z = 2. The Cu-thiourea complex is arranged as a Cu(I) tetranuclear ion, [Cu(4)(tu)(12)](4+), sited on a crystallographic inversion center. All copper ions are in a tetrahedral coordination with thiourea ligands and located at alternate sites on an eight-membered, crown-like ring.

Journal Article↗
PubMed1978

Bioassay of 1-phenyl-2-thiourea for possible carcinogenicity.

A bioassay of 1-phenyl-2-thiourea for possible carcinogenicity was conducted using Fischer 344 rats and B6C3F1 mice. 1-Phenyl-2-thiourea was administered in the feed, at either of two concentrations, to groups of 50 male and 50 female animals of each species. The high and low concentrations of 1-phenyl-2-thiourea utilized in the chronic bioassay were, respectively, 120 and 60 ppm for rats and 300 and 150 ppm for mice. Twenty animals of each species and sex were placed on test as controls. A 78-week period of chemical administration was followed by an additional observation period of 26 weeks for rats and 13 weeks for mice. Adequate numbers of animals in all groups survived sufficiently long to be at risk from late-developing tumors. Distinct dose-related depression of mean body weight gain was observed in male and female mice when compared with their controls, but growth retardation was not observed in any dosed rat group. In addition, since no significant accelerated mortality or other toxic effects were associated with the dietary administration of 1- phenyl-2-thiourea to rats, it is possible that the compound was not administered to these animals at the maximum tolerated concentrations. There were no tumors in either sex of rats or mice for which a significant positive association could be established between chemical administration and tumor incidence. Under the conditions of this bioassay, 1-phenyl-2-thiourea was not carcinogenic to Fischer 344 rats or B6C3F1 mice.

Journal Article↗
PubMed2001

C-H activation with elemental sulfur: synthesis of cyclic thioureas from formaldehyde aminals and S8.

The C-H activation of cyclic formaldehyde aminals LCH2 (L = RN-CH2CH2CH2-NR and RNCH2CH2-NR, R = Me, Et, iPr, tBu, or Ph) with S8 proceeds at unusually low temperatures (T< 160 degrees C) and results in the formation of the respective thioureas LC=S and H2S. The reaction constitutes a new, solvent-free method for the synthesis of thioureas that eliminates the toxic and highly flammable CS2. For R = tBu, the ionic carbenium thiocyanates [LCH]+ SCN- dominate the product spectrum and the respective thioureas are obtained in low yield. The reactivity of the analogous sulfur and oxygen ring systems towards S8 was investigated. 1,3-Dithiolane is cleanly converted into 1,3-dithiolane-2-thione (S8, 14 d, 190 degrees C) and resembles the cyclic formaldehyde aminals in this respect. 1,3-Dioxolane (L = OCH2CH2O) is completely inert towards sulfur even under forceful reaction conditions (190 degrees C, 14 d). The formation of thioureas from aminals was investigated at the CBS-4 and B3LYP/6-31G(d) levels of theory.

Formaldehyde↗
PubMed2001

Thiourea enhances mapping of the proteome from murine white adipose tissue.

Adipose tissue imposes problems in two-dimensional (2-D) analysis due to its extremely high content of fat. To improve protein separation detergents and chaotropes were varied in the IEF step. The most important factor for obtaining distinct spots in the 2-D gel was whether thiourea was included or not. Many high molecular weight spots became resolved by using thiourea, while no spots disappeared or showed inferior characteristics, thus approximately twice as many spots were possible to quantify. Hydrophobic indices were compared for a set of proteins that gave rise to sharper spots with proteins that were not improved on the use of thiourea. The comparison did not give any statistically significant difference between the two groups of proteins. One of the effects obtained by inclusion of thiourea was that the dominating protein, serum albumin, appeared as more condensed spots allowing other minor proteins to be detected. This work resulted in a protocol which greatly enhances the resolution of proteins in adipose tissue. A 2-D map of mouse white adipose tissue from epididymal fat pads was constructed in which 140 spots were identified by mass spectrometry. This work lays the ground for our further studies on white adipose tissue in metabolic diseases such as obesity and dyslipidemia.

Adipose Tissue↗
PubMed1985

Thiourea induces DNA repair synthesis in primary rat hepatocyte cultures and gene mutations in V79 Chinese hamster cells.

Thiourea was investigated for its capacity to cause DNA alterations in cultured mammalian cells. The induction of DNA repair in primary rat hepatocyte cultures and of gene mutations in V79 Chinese hamster cells were used as biological endpoints. In hepatocytes, thiourea elicited a linear increase in DNA repair replication in the concentration range tested (5-25 mM). In V79 cells, thiourea (10-40 mM) significantly increased the frequency of 8-azaguanine-resistant mutants. The present results show that thiourea is weakly, but definitely, genotoxic and mutagenic in cultured mammalian cells.

Animals↗
PubMed1985

Interaction of thiourea with band 3 in human red cell membranes.

Although urea transport across the human red cell membrane has been studied extensively, there is disagreement as to whether urea and water permeate the red cell by the same channel. We have suggested that the red cell anion transport protein, band 3, is responsible for both water and urea transport. Thiourea inhibits urea transport and also modulates the normal inhibition of water transport produced by the sulfhydryl reagent, pCMBS. In view of these interactions, we have looked for independent evidence of interaction between thiourea and band 3. Since the fluorescent stilbene anion transport inhibitor, DBDS, increases its fluorescence by two orders of magnitude when bound to band 3 we have used this fluorescence enhancement to study thiourea/band 3 interactions. Our experiments have shown that there is a thiourea binding site on band 3 and we have determined the kinetic and equilibrium constants describing this interaction. Furthermore, pCMBS has been found to modulate the thiourea/band 3 interaction and we have determined the kinetic and equilibrium constants of the interaction in the presence of pCMBS. These experiments indicate that there is an operational complex which transmits conformational signals among the thiourea, pCMBS and DBDS sites. This finding is consistent with the view that a single protein or protein complex is responsible for all the red cell transport functions in which urea is involved.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1984

Thiourea: the antioxidant of choice for the purification of proteins from phenol-rich plant tissues.

Metabisulfite, diethyldithiocarbamate, and thiourea are potent phenoloxidase inhibitors commonly used during the extraction of plant proteins. Their effects on several amino acid derivatives and peptides are reported. Important and pH-dependent changes are induced by metabisulfite in the uv-absorption spectrum of N-acetyltryptophanamide but not of N-acetyltyrosinamide. Similar spectral changes are also induced in tryptophanyl-containing peptides. Neither diethyldithiocarbamate nor thiourea modified the spectral properties of tryptophan or tyrosine. Cysteinyl groups are rapidly modified by diethyldithiocarbamate, especially in the lower pH range, but not by metabisulfite or thiourea. Diethyldithiocarbamate as well as metabisulfite interfere with cysteinyl groups. It is concluded that thiourea is the most appropriate reagent for use as a phenoloxidase inhibitor.

Antioxidants↗
PubMed1984

Effect of thiourea on PCMBS inhibition of osmotic water transport in human red cells.

The organomercurial reagent p-chloromercuribenzene sulfonate (PCMBS) is an inhibitor of osmotic water permeability in the human red cell membrane. We have found that thiourea, when added along with PCMBS to a red cell suspension, interferes with this inhibition and at high enough concentrations prevents the inhibition from developing altogether. For a 2 mM PCMBS concentration Ki = 3 +/- 1 mM. When thiourea is added at a later time, the PCMBS inhibition, which normally takes about 20 min to develop fully, is halted and remains fixed at the value attained by that time. Thiourea also inhibits the reversal of PCMBS inhibition by a 10 mM concentration of cysteine, the half-time for reversal increasing by more than an order of magnitude when [thiourea] = 50 mM. Possible implications for the nature of the water and urea transport pathways across the red cell membrane are discussed.

4-Chloromercuribenzenesulfonate↗