A Novel N-Tert-Butyl Derivatives of Pseudothiohydantoin as Potential Target in Anti-Cancer Therapy

Tumors are currently more and more common all over the world; hence, attempts are being made to explain the biochemical processes underlying their development. The search for new therapeutic pathways, with particular emphasis on enzymatic activity and its modulation regulating the level of glucocorticosteroids, may contribute to the development and implementation of new therapeutic options in the treatment process. Our research focuses on understanding the role of 11β-HSD1 and 11β-HSD2 as factors involved in the differentiation and proliferation of neoplastic cells. In this work, we obtained the 9 novel N-tert-butyl substituted 2-aminothiazol-4(5H)-one (pseudothiohydantoin) derivatives, differing in the substituents at C-5 of the thiazole ring. The inhibitory activity and selectivity of the obtained derivatives in relation to two isoforms of 11β-HSD were evaluated. The highest inhibitory activity for 11β-HSD1 showed compound 3h, containing the cyclohexane substituent at the 5-position of the thiazole ring in the spiro system (82.5% at a conc. 10 µM). On the other hand, the derivative 3f with the phenyl substituent at C-5 showed the highest inhibition of 11β-HSD2 (53.57% at a conc. of 10 µM). A low selectivity in the inhibition of 11β-HSD2 was observed but, unlike 18β-glycyrrhetinic acid, these compounds were found to inhibit the activity of 11β-HSD2 to a greater extent than 11β-HSD1, which makes them attractive for further research on their anti-cancer activity.

Convenient Synthesis of Thiohydantoins, Imidazole-2-thiones and Imidazo[2,1-b]thiazol-4-iums from Polymer-Supported α-Acylamino Ketones

The preparation of 5-methylene-thiohydantoins using solid-phase synthesis is reported in this paper. After sulfonylation of immobilized Ser (t-Bu)-OH with 4-nitrobenzenesulfonyl chloride followed by alkylation with various bromoketones, the 4-Nos group was removed and the resulting polymer-supported α-acylamino ketones reacted with Fmoc-isothiocyanate. Cleavage of the Fmoc protecting group was followed by the spontaneous cyclative cleavage releasing the 5-methylene-thiohydantoin derivatives from the polymer support. Reduction with triethylsilane (TES) yielded the corresponding 5-methyl-thiohydantoins. When Fmoc-isothiocyanate was replaced with alkyl isothiocyanates, the trifluoroacetic acid (TFA) mediated cleavage from the polymer support, which was followed by the cyclization reaction and the imidazo[2,1-b]thiazol-4-iums were obtained. Their conversion in deuterated dimethylsulfoxide led to imidazole-2-thiones.

Inhibition of Cancer-Associated Mutant Isocitrate Dehydrogenases by 2-Thiohydantoin Compounds

Somatic mutations of isocitrate dehydrogenase 1 (IDH1) at R132 are frequently found in certain cancers such as glioma. With losing the activity of wild-type IDH1, the R132H and R132C mutant proteins can reduce α-ketoglutaric acid (α-KG) to d-2-hydroxyglutaric acid (D2HG). The resulting high concentration of D2HG inhibits many α-KG-dependent dioxygenases, including histone demethylases, to cause broad histone hypermethylation. These aberrant epigenetic changes are responsible for the initiation of these cancers. We report the synthesis, structure-activity relationships, enzyme kinetics, and binding thermodynamics of a novel series of 2-thiohydantoin and related compounds, among which several compounds are potent inhibitors of mutant IDH1 with Ki as low as 420 nM. X-ray crystal structures of IDH1(R132H) in complex with two inhibitors are reported, showing their inhibitor-protein interactions. These compounds can decrease the cellular concentration of D2HG, reduce the levels of histone methylation, and suppress the proliferation of stem-like cancer cells in BT142 glioma with IDH1 R132H mutation.

Microwave assisted synthesis of novel functionalized hydantoin derivatives and their conversion to 5-(Z) arylidene-4H-imidazoles

2-(Alkyl-1-yl)-1H-imidazol-5(4H)-ones 5a-n were synthesized via nucleophilic substitution of the methylsulfanyl group of the corresponding 2-(methylthio)-1H-imidazol-5(4H)-ones 3a-c with suitably substituted secondary amines. The starting 2-thioxo- imidazolidin-4-ones 2a,2b were prepared by condensation of thiohydantoin and benzo[b]-thiophene-3-carbaldehyde or benzofuran-3-carbaldehyde under microwave irracdiation (MW) conditions. 2-Methylthio derivatives 3a-c were prepared by treatment of 2a-b with methyl iodide in the presence of aqueous sodium hydroxide.

Rhodanine and thiohydantoin derivatives for detecting tau pathology in Alzheimer's brains

A novel series of rhodanin (RH) and thiohydantoin (TH) derivatives were designed and synthesized for detecting tau pathology in the brains of patients with Alzheimer's disease (AD). In experiments in vitro using tau and β-amyloid (Aβ) aggregates, the TH derivative, TH2, showed high specific binding to tau aggregates. In hippocampal sections obtained from AD patients, TH2 intensely stained neurofibrillary tangles. In experiments using normal mice, [(125)I]TH2 showed good uptake (1.54%ID/g, 2 min postinjection) into and a rapid washout (0.25%ID/g, 60 min postinjection) from the brain. [(123)I]TH2 should be further investigated as a potential imaging agent for detecting tau pathology.

A rapid and efficient ultrasound-assisted synthesis of 5,5-diphenylhydantoins and 5,5-diphenyl-2-thiohydantoins

To obtain a rapid, efficient and mild synthesis of 5,5-diphenylhydantoin and 5,5-diphenyl-2-thiohydantoin derivatives, ultrasonic irradiation has been applied to the reaction mixtures containing substituted benzils and urea or thiourea derivatives catalyzed by KOH in DMSO/H(2)O, which allowed us to achieve products at room temperature in a good yield and short time without any side product. This convenient procedure will allow a further increase of the diversity within the hydantoin family.

Expedient Lewis Acid Catalyzed Synthesis of a 3-Substituted 5-Arylidene-1-methyl-2-thiohydantoin Library

An efficient and rapid solution phase combinatorial synthesis of a 3-substituted 5-arylidene-1-methyl-2-thiohydantoin library was developed. The salient feature for this library production procedure is the addition of the Lewis acid catalyst, indium(III) trifluoromethanesulfonate, which serves to facilitate the direct condensation of aldehydes with 3-substituted 1-methyl-2-thiohydantoins. Use of this Lewis acid catalyst has resulted in faster reaction times, higher conversions and better purity profiles for these condensation reactions as compared to traditional uncatalyzed reactions. The resulting 315 member library of 3-substituted 5-arylidene-1-methyl-2-thiohydantoin is described.

The lipophilicity estimation of 5-arylidene derivatives of (2-thio)hydantoin with antimycobacterial activity

The lipophilicity of antituberculotic 5-arylidene derivatives of (thio)hydantoin, thioacetazone and isoniazid has been determined by reversed-phase thin-layer chromatography (RP-TLC). Mixtures of acetone and water (with acetone content 60-85%) were used as the mobile phase. The R(M) (relative lipophilicity) of each compound (except isoniazid) decreased linearly with the increasing concentration of acetone. The partition coefficients (log P) of the compounds were calculated by the use of eight computer programs (ClogP, KowWin, XlogP, AlogPs, CAChe, Pallas, Interactive analysis and Slipper) and compared with the experimental lipophilicity (R(M0)). According to the observations the best tools for in silico predicting log P of (2-thio)hydantoins are programs KowWin and AlogPs.

On Formation of Thiohydantoins from Amino Acids under Acylation Conditions

Reactions of glycine, alanine, and phenylalanine with acetic anhydride and ammonium thiocyanate give the 1-acetyl-2-thiohydantoins 2a-c. These results appear to contradict prior literature reports pertaining to this reaction.

Fluorous parallel synthesis of a hydantoin/thiohydantoin library

Fluorous tagging strategy is applied to solution-phase parallel synthesis of a library containing hydantoin and thiohydantoin analogs. Two perfluoroalkyl (Rf)-tagged alpha-amino esters each react with six aromatic aldehydes under reductive amination conditions. Twelve amino esters then each react with 10 isocyanates and isothiocyanates in parallel. The resulting 120 ureas and thioureas undergo spontaneous cyclization to form the corresponding hydantoins and thiohydantoins. The intermediate and final product purifications are performed with solid-phase extraction (SPE) over FluoroFlash cartridges, no chromatography is required. Using standard instruments and straightforward SPE technique, one chemist accomplished the 120-member library synthesis in less than five working days, including starting material synthesis and product analysis.

Substituted 5,5'-diphenyl-2-thioxoimidazolidin-4-one as CB1 cannabinoid receptor ligands: synthesis and pharmacological evaluation

A set of 30 substituted 5,5'-diphenyl-2-thioxoimidazolidin-4-one (thiohydantoins) derivatives was synthesized, and their affinity for the human CB(1) cannabinoid receptor has been evaluated. These compounds are derived from the previously described cannabinoid ligands 5,5'-diphenylimidazolidine-2,4-dione (hydantoins). The replacement of the oxygen by a sulfur leads to an increase of the affinity while the function-i.e., inverse agonism-determined by [(35)S]GTPgammaS experiments remains unaffected. Finally, to evaluate the molecular parameters that could influence the affinity of the thiohydantoins, molecular electrostatic potential as well as lipophilicity calculations were undertaken on representative thiohydantoins and hydantoins derivatives. In conclusion, 5,5'-bis-(4-iodophenyl)-3-butyl-2-thioxoimidazolidin-4-one (31) and 3-allyl-5,5'-bis(4-bromophenyl)-2-thioxoimidazolidin-4-one (32) possess the highest affinity for the CB(1) cannabinoid receptor described to date for the hydantoin and thiohydantoins series when compared in a same bioassay.

Parallel solid-phase synthesis of disubstituted (5-biphenyltetrazolyl) hydantoins and thiohydantoins targeting the growth hormone secretagogue receptor

An efficient solid-phase protocol for the synthesis of substituted (5-biphenyltetrazolyl)-hydantoins and -thiohydantoins has been developed. Suzuki cross-coupling between resin-bound 2-(tetrazol-5-yl)-phenylborinane and 4-bromobenzaldehyde gave the corresponding tetrazolylbiphenyl aldehyde. Subsequent reductive amination using amino acid esters gave the pivotal resin bound amino acid esters which were transformed to hydantoins or thiohydantoins via two routes: (i) treatment with isocyanates or isothiocyanates or (ii) successive treatment with triphosgene and primary amines. Using molecular modeling, we were able to jump from L-692,429, a well known non-peptidyl growth hormone secretagogue (GHS), to biphenyltetrazolyl hydantoins, obtaining compounds with IC(50) values below 600 nM after two iterative cycles only.

Design, Synthesis, and Biological Evaluation of Thio-Containing Compounds with Serum HDL-Cholesterol-Elevating Properties

A novel series of substituted sulfanyldihydroimidazolones (1) that modulates high-density lipoprotein cholesterol (HDL-C) has been reported to have HDL-elevating properties in several animal models. Concerns about the chemical and metabolic stability of 1 directed us to explore the structure-activity relationship (SAR) of a related series of substituted thiohydantoins (2). Expansion of the scope of the thiohydantoin series led to exploration of compounds in related thio-containing ring systems 3-7 and the N-cyanoguanidine derivative 8. Compounds were tested sequentially in three animal models to assess their HDL-C elevating efficacy and safety profiles. Further evaluation of selected compounds in a dose-response paradigm culminated in the identification of compound 2.39 as a candidate compound for advanced preclinical studies.

Microwave-enhanced liquid-phase synthesis of thiohydantoins and thioxotetrahydropyrimidinones

An efficient, microwave-assisted method for the liquid-phase combinatorial synthesis of 3,5-disubstituted thiohydantoins and 3,5-disubstituted 2-thioxotetrahydropyrimidin-4-ones has been developed. In synthesizing thiohydantoins, Fmoc-protected amino acids were coupled with polymer support and then deprotected to give primary amines. While in synthesizing thioxotetrahydropyrimidinones, 3-chloropropionyl chloride was immobilized to the support and subsequently reacted with various amines to form secondary amines. The PEG bound primary/secondary amines then were incorporated with various isothiocyanates to give thiourea intermediates and concomitant cyclization/cleavage steps occurred under mild basic condition. The desired products were then liberated from the soluble matrix in good yield and purity. All reactions described here were performed under microwave irradiation.

Solid-phase synthesis of linear ureas tethered to hydantoins and thiohydantoins

An efficient method for the solid-phase synthesis of hydantoins and thiohydantoins tethered to ureas, starting from a resin-bound amino acid, is presented. Following reduction of the amide with borane-THF, a second amino acid was selectively coupled to the primary amine followed by treatment of the secondary amine by an isocyanate to generate the corresponding urea. Hydantoin and thiohydantoin formation was achieved through the use of carbonyldiimidazole and thiocarbonyldiimidazole, respectively. Cleavage from the solid support using hydrogen fluoride, followed by extraction and lyophilization, provided the desired urea-linked heterocyclic compounds in good yield and high purity.

Synthesis of 2-thiohydantoins and their S-glucosylated derivatives as potential antiviral and antitumor agents

A series of 3-alkyl-5-((Z))-arylidene-2-thiohydantoins 4a-1 were synthesized from the direct condensation of the aromatic aldehydes with 3-alkyl-2-thiohydantoins 3a-c, which in turn were prepared from the reaction of glycine (1) and alkyl isothiocyanates 2a-c. The alkylation of 4a-1 with methylthioethyl chloride gave 5-((Z))-arylidene-3-alkyl-S-(2-methylthioethyl)-2-thiohydantoins 5a-e. S-Glucosylation took place on the reaction of 4a-1 with 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide under anhydrous alkaline conditions. These structures have been confirmed from a model study of the coupling of 4a with methylthioethyl chloride and alpha-D-glucose pentaacetate, respectively under Lewis acid conditions.

Solution-phase combinatorial chemistry

The use of solution phase techniques has been explored as an alternative to solid-phase chemistry approaches for the preparation of arrays of compounds in the drug discovery process. Solution-phase work is free from some of the constraints of solid-phase approaches but has disadvantages with respect to purification. This article will also illustrate some of the advances made in recent years in solution phase array chemistry including using supported reagents and simple extractive protocols for the effective preparation of high quality samples.

Multiple solid-phase synthesis of hydantoins and thiohydantoins

A novel general protocol for the construction of hydantoins and thiohydantoins on a solid support has been developed. Using this novel methodology, the synthesis of a diverse 96-compound library has been achieved. Resin-bound dipeptides are cyclised via the formation of an intermediate isocyanate or isothiocyanate on resin as the key step in the strategy.

A method for preparation of amino acid thiohydantoins from free amino acids activated by acetyl chloride for development of protein C-terminal sequencing

A novel and efficient method to prepare amino acid thiohydantoins, which are required as reference standards for development of C-terminal protein sequencing, is reported. Amino acid thiohydantoins were prepared using a straightforward method involving reaction of 20 free amino acids with acetyl chloride as activating reagent and trimethylsilyl isothiocyanate (TMS-ITC) as derivatizing reagent. The products were characterized by HPLC, uv spectra, amino acid analysis, MS, and NMR. Different reaction conditions were investigated and the chemical mechanism of the formation of amino acid thiohydantoins was illustrated.

Fused 2-thiohydantoin derivatives: evaluation as potential antioxidants

A series of fused 5,5-diphenyl and 5-arylidene-2-thiohydantoin derivatives were examined for their oxygen free radical inhibitory and radical scavenging properties (RSC) using both an enzymic and non-enzymic biological generators of free radicals. Non-enzymic lipid peroxidation (OH. radicals) was assayed as the amount of malondialdehyde (MDA) that had been formed during incubation of boiled rat liver microsomes in the presence of ascorbic acid and ferric ions. Superoxide anions (.O2- anion radicals) were generated enzymatically in the xanthine-xanthine oxidase system. Among the 20 investigated compounds only four fused arylidene 2-thiohydantoin derivatives showed weak antioxidant activity scavenging OH. radicals. There is a relationship between the electrophilic OH. radical scavenging properties (RSC) of the tested molecules and the value of their HOMO energy derived from semiempirical MO calculations.

5-substituted-2-thiohydantoin analogs as a novel class of antitumor agents

Certain series of 2-thiohydantoin derivatives, carrying various substituents at position 5 such as 5-bromo-2-thienylmethylene, 5-(2-carboxyphenylthio)-2-thienylmethylene and 2-methylene-4H-thieno[2,3-b][1]benzothiopyran-4-one, were evaluated for their antitumor activity. Compound 5-(5-bromo-2-thienylmethylene)-3-morpholinomethyl-2-(2,3,4,6 -tetra-O-acetyl -beta-D-glucopyranosylthio)hydantoin proved to possess a broad spectrum antitumor activity against a wide range of different human cell lines of nine tumor subpanels causing both cytostatic and cytotoxic effects, resulting in full panel median growth inhibition (GI50) and total growth inhibition (TGI), with a median lethal concentration (LC50) at 15.1, 41.7 and 83.2 microM, respectively. On the other hand, compound 5-(5-bromo-2-thienylmethylene)-2-thiohydantoin and compound 5-(5-bromo-2-thienylmethylene)-3-phenyl-2- (2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl-thio)hydantoin showed potential selectivity against leukemia cell lines. Further derivatization of these compounds, deduced from the obtained tentative structure-activity relationships, may lead to more potent agents.

Automated carboxy-terminal sequence analysis of polypeptides containing C-terminal proline

Proteins and peptides can be sequenced from the carboxy-terminus with isothiocyanate reagents to produce amino acid thiohydantoin derivatives. Previous studies in our laboratory have focused on automation of the thiocyanate chemistry using diphenyl phosphoroisothiocyanatidate (DPP-ITC) and pyridine to derivatize the C-terminal amino acid to a thiohydantoin and sodium trimethylsilanolate for specific hydrolysis of the derivatized C-terminal amino acid (Bailey, J. M., Nikfarjam, F., Shenoy, N. S., and Shively, J. E. (1992) Protein Sci. 1, 1622-1633). A major limitation of this approach was the inability to derivatize C-terminal proline. We now describe chemistry based on the DPP-ITC/pyridine reaction which is capable of derivatizing C-terminal proline to a thiohydantoin. The reaction of DPP-ITC/pyridine with C-terminal proline rapidly forms an acyl isothiocyanate which is capable of forming a quaternary amine containing thiohydantoin. Unlike formation of peptidylthiohydantoins with the other 19 commonly occurring amino acids in which cyclization to a thiohydantoin is concomitant with loss of a proton from the amide nitrogen, proline has no amide proton and as a result the newly formed proline thiohydantoin contains an unprotonated ring nitrogen. This cyclic structure if left unprotonated will regenerate C-terminal proline during the cleavage reaction. However, if protonated by the addition of acid, the proline thiohydantoin ring is stabilized and can be readily hydrolyzed to proline thiohydantoin and a shortened peptide by the addition of water vapor or alternatively by sodium or potassium trimethylsilanolate, the reagent normally used for the cleavage reaction. By introducing vaporphase trifluoroacetic acid (TFA) for the protonation reaction and water vapor for the hydrolysis reaction we have been able to automate the chemistry required for derivatization of C-terminal proline.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on the synthesis and structure-activity relationships of 5-(3'-indolal)-2-thiohydantoin derivatives as aldose reductase enzyme inhibitors

A new series of 5-(3'-indolal)-2-thiohydantoin derivatives was synthesized and tested for the ability to inhibit bovine lens aldose reductase (AR) enzyme. The compounds were prepared by condensation of substituted indole-3-aldehyde derivatives with 2-thiohydantoin. The capacity of inhibiting the semi-purified bovine lens enzyme in vitro was observed for several of the compounds tested. One of them was found to be effective in reducing the enzyme activity compared with a corresponding well-known AR inhibitor.

Studies in C-terminal sequencing: new reagents for the synthesis of peptidylthiohydantoins

In previous studies aimed at the sequencing of peptides and proteins from the carboxy terminus, we have derivatized the C-terminus to a thiohydantoin using acetic anhydride and trimethylsilylisothiocyanate (TMS-ITC) and subsequently hydrolyzed it to form a shortened peptide capable of further degradation and an amino acid thiohydantoin which can be identified by reverse-phase HPLC. Current limitations to this chemistry include an inability to derivatize proline and low yields with asparagine and aspartic acid residues (Bailey et al., 1992). In an attempt to solve some of these problems, we have investigated the use of reagents other than acetic anhydride for the activation of the C-terminal carboxylic acid. These include 2-fluoro-1-methylpyridinium tosylate, 2-chloro-1-methylpyridinium iodide, and acetyl chloride. Addition of TMS-ITC to peptides activated by the 2-halo-pyridinium salts formed the expected peptidylthiohydantoin, but in addition formed a peptide chemically modified at the C-terminus which was blocked to C-terminal sequence analysis. This derivative was not obtained when either acetic anhydride or acetyl chloride was used for activation. Formation of this derivative was found to require the presence of an isothiocyanate reagent in addition to the halo-pyridinium salt. Sodium thiocyanate, TMS-ITC, and a new reagent for thiohydantoin synthesis, tributyltinisothiocyanate (TBSn-ITC), were all found to be capable of forming this analogue. Structural elucidation of the C-terminally modified amino acid revealed it to be a 2-imino-pyridinium analogue. Formation of this C-terminally blocked peptide could be minimized by the use of the 2-chloro-pyridinium reagent, rather than the 2-fluoro reagent, and by performing the reaction at a temperature of 50 degrees C or lower. The 2-halo-pyridinium reagents offer potential advantages over the use of acetic anhydride for activation of the C-terminal carboxylic acid. These include: milder reaction conditions, faster reaction times, and the ability to sequence through C-terminal aspartic acid. The TBSn-ITC reagent was found to be comparable to TMS-ITC for formation of peptidylthiohydantoins.

Formation of proline thiohydantoin with ammonium thiocyanate: progress towards a viable C-terminal amino-acid-sequencing procedure

Pure amino acid thiohydantoins are required as reference standards for development of C-terminal-sequencing procedures based on thiohydantoin formation of the C-terminal amino acids of peptides and proteins. Proline thiohydantoin was prepared using a straightforward method involving reaction of acetylproline with ammonium thiocyanate. It was characterized by UV spectrophotometry, mass spectrometry and back-hydrolysis to the free amino acid. These data establish unequivocally that the thiocyanate procedure is applicable to proline as well as to the other common amino acids. This work also validates earlier claims that proline thiohydantoin can be prepared by reaction with thiocyanic acid.

Studies on cardiotonic agents. IV. Synthesis of novel 1-(6,7-dimethoxy-4-quinazolinyl)piperidine derivatives carrying substituted hydantoin and 2-thiohydantoin rings

A series of novel 1-(6,7-dimethoxy-4-quinazolinyl)piperidines carrying substituted hydantoin and 2-thiohydantoin rings was synthesized and examined for cardiotonic activity in anesthetized dogs. Introduction of isopropyl and sec-butyl group at the 5-position of the hydantoin and thiohydantoin rings led to potent inotropic activity. Effects of insertion of an alkyl chain between the piperidine and the hydantoin rings were also examined. The structural requirements necessary for optimal cardiotonic activity within the series were investigated.

Novel inhibitors of enkephalin-degrading enzymes. II: N5'-substituted-4-thioxohydantoic acids as aminopeptidase inhibitors

Some 2-substituted-(2'-aminophenyl)-4-thioxohydantoic acids (o-amino PTC-amino acids) have antinociceptive activity when administered (icv) alone (IC50 = 0.04-0.87 microM/animal) and show a striking prolongation of the antinociceptive action of (D-Ala-2 D-Leu5)-enkephalin (DADL) in combination. The effects are thought to be mediated via opioid receptors since they are naloxone-reversible. Although inhibitors of the enkephalin degrading puromycin-insensitive, bestatin-sensitive aminopeptidase (possibly aminopeptidase M) their action is weak (IC50 = 32 microM leucine, 536 microM, glycine) and they might be considered to have a direct antinociceptive effect on opioid receptors. The titled compounds constitute novel 'lead' compounds for the development of potent aminopeptidase M inhibitors.

Synthesis of 3-dialkylaminopropyl-2-thiohydant derivatives as potential antiarrhythmic agents

A series of 3-dialkylaminopropyl-5-monosubstituted-2-thiohydantoins were synthesized as potential antiarrhythmic agents; their pharmacological activity is comparable to that of quinidine, but weaker than that of phenytoin.

Preparation and antidiabetic activity of cyclic sulfonylthiourea derivatives

3-Substituted 5-methyl-1-(p-[(3,5-dimethyl)pyrazol-1-yl]-, 5-methyl-1-(p-[(5-methyl-3-carboxy)pyrazol-1-yl]-, 1-(p-[(3-methyl-5-phenyl)pyrazol-1-yl]-, and 1-(p-[(3-methyl-4-bromo-5-phenyl)pyrazol-1-yl]benzenesulfonyl)-2-thiohydantoin and their 5-methyl-2-thiohydantoin and 5,6-dihydro-4(3H)-oxo-2(1H)-pyrimidinethione derivatives were prepared for evaluation as hypoglycemic agents. Biological testing showed that some of these compounds possessed antidiabetic activity.

Use of thiocyanic acid to form 2-thiohydantoins at the carboxyl terminus of proteins

The chemistry of the formation of 2-thiohydantoins on the carboxyl terminal of peptides or proteins was investigated. It was found that thiocyanic acid was much more reactive for the formation of 2-thiohydantoins than were the thiocyanate salts. The physical reasons for this observation are explained. The kinetics of the reaction of a number of proteins, and some of their fragments, with thiocyanic acid were also determined. Simple and safe procedures for the preparation of anhydrous thiocyanic acid solutions were devised. The prospective application of these procedures to sequencing from the carboxyl terminal of a polypeptide is discussed.

Quantitative mass spectral identification of p-bromophenylthiohydantoins from Edman degradations by tetradeuterated internal standards

p-Bromophenylisothiocyanate is a reagent well suited for the Edman degradation of peptide chains[1-5]. The relative rate of the coupling reaction at the N-terminus is slightly more rapid than with phenyl- or methylisothiocyanate, but less rapid than with pentafluorophenylisothiocyanate. The latter reagent, however, is rapidly hydrolyzed under the conditions of the coupling reaction. The p-bromo substituent facilitates mass spectral identification of the p-bromophenylthiohydantoins obtained, due to its characteristic double peak[1-4]. Quantitation of the amount of p-bromophenylthiohydantoin obtained can easily be achieved in the parent mass spectrum by addition of a known amount of tetradeutero-p-bromophenylthiohydantoin as an internal standard. The tetradeuterated standards give rise to molecular ion peaks four mass units higher than the corresponding undeuterated probes. Standard and probe volatilize almost equally well. The composition in the vapor indicated by the H/D ratio reflects the molar concentrations over the entire range of probe evaporation. A procedure for the preparation of the tetradeutero-p-bromophenyl-isothiocyanate and the respective tetradeuterated amino acid p-bromophenylthiohydantoins is given.

A search for new anticonvulsant compounds among 3-aryl-5-benzylidene derivatives of 2-thiohydantoin

13 New 3-aryl-5-benzylidene-2-thiohydantoins were obtained by condensation of 3-o-tolyl- and 3-m-tołyl-2--thiohydantoin with aromatic aldehydes. The structure of the obtained compounds was confirmed by IR spectra. Derivatives of 2-thiohydantoin 1-13 show weak anticonvulsant activity in pentetrazole test and show no protecting activity against the maximal electric shock.