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PubMed1996

Synthesis of an Enantiomerically Pure Serine-Derived Thiazole.

Previously reported methods for preparing enantiomerically pure thiazoles are inadequate for the synthesis of inherently labile O-alkyl serine-derived thiazoles. The intermediateN-Boc-(O-methylseryl) thiazolines are very susceptible to tautomerization, even under neutral conditions (Scheme 5). Herein, it is demonstrated that the choice of N-protecting group is critical to the preservation of enantiomeric purity. Thus, using an N-trityl protecting group, O-methyl serine was converted to the corresponding N-Boc-(O-methylseryl) thiazole 3 with no appreciable epimerization as indicated by (19)F and (1)H NMR of the corresponding Mosher's amide.

Journal Article↗
PubMed1991

Biosynthesis of the thiazole moiety of thiamin (vitamin B1) in higher plant chloroplasts.

The chloroplast stromal proteins from spinach condense the two heterocyclic moieties of vitamin B1--4-methyl-5-(beta-hydroxyethyl)thiazole and 2-methyl-4-amino-5-hydroxymethylpyrimidine--in the presence of MgATP. We have taken advantage of this observation to study thiazole synthesis. We present data indicating that pyruvate, glyceraldehyde 3-phosphate, tyrosine, cysteine, and MgATP are required for this synthesis and that pyruvate and glyceraldehyde 3-phosphate can be replaced by 1-deoxy-D-threo-2-pentulose. The thiazole synthesis occurs at a sustained, low rate of 140 pmol per mg of protein per hr.

Journal Article↗
PubMed2002

Flat versus twisted rotamers of 2,4-disubstituted thiazoles: the effect of intermolecular hydrogen bonds.

In the title compounds, 2-amino-4-(2-chloro-4,5-dimethoxyphenyl)-1,3-thiazole, C(11)H(11)ClN(2)O(2)S, (I), and 4-(2-chloro-4,5-dimethoxyphenyl)-2-methyl-1,3-thiazole, C(12)H(12)ClNO(2)S, (II), the dihedral angles between the thiazole moiety and the chloroaryl group are 51.61 (10) and 8.44 (14), respectively. This difference is a consequence of intermolecular hydrogen bonds forcing the stabilization of a twisted rotamer in (I). Substitution of the amino function by a methyl group precludes these contacts, giving a flat rotamer in (II).

Journal Article↗
PubMed2002

Synthesis and antitumor evaluation of new polysubstituted thiazole and derived thiazolo[4, 5-d]pyrimidine systems.

The synthesis of three categories of compounds containing the 1H-pyrazole ring linked to some dihydrothiazoles, thiazolidinones, and thiazolo[4, 5-d]pyrimidines through different linkages is described. Nine of the newly synthesized target compounds were selected by the NCI for in-vitro antitumor screening. Four compounds, namely 4a, 4b, 13, and 14, exhibited a broad spectrum of antitumor activity against most of the tested tumor cell lines. Compound 4a, 3-phenyl-4-amino-5-(3, 5-dimethyl-1-phenyl-1H-pyrazole-4-methylidenehydrazinocarbonyl)thiazole-2(3H)-thione proved to be the most active antitumor agent in the present study with GI(50), TGI, and LC(50) MG-MID values of 3.93, 41.7, and 91.2 microM, respectively. The same compound also exhibited high selectivity towards CNS SNB-75 and Ovarian IGROV1 cancer cell lines at both the GI(50) and TGI levels. Compound 4b, 3-(4-chlorophenyl)-4-amino-5-(3, 5-dimethyl-1-phenyl-1H-pyrazole-4-methylidenehydra-zinocarbonyl) thiazole-2(3H)-thione showed nearly the same pattern of activity as 4a but to a lesser extent. Compounds 13 and 14 displayed moderate antitumor activity against most of the tested tumor cell lines with GI(50) MG-MID values range of 20.4-80.6 microM and TGI MG-MID values of 55.5-95.5 microM.

Antineoplastic Agents↗
PubMed1994

New NO-donors with antithrombotic and vasodilating activities, VII: Z/E-isomerism in thiazole- and 1,3,4-thiadiazole-2-nitrosimines.

In thiazole- (23 compounds) and 1,3,4-thiadiazole-2-nitrosimines (20 compounds) Z/E-isomers were described by 1H-NMR-spectroscopy. There is a mutual conversion of the isomers. The coalescence temp. (Tc) mostly is 310 K. In the thiazole series, however, for five compounds higher energy barriers are observed. This is due to substituents in 4-position with electron withdrawing properties. The Tc is increased when the compounds are dissolved in water instead of DMSO. Hereby it is concluded that the isomers have Ze or Ee configuration. It is made probable that the low field signal for the substituent in 3-position corresponds to the Ze-isomer, which has a slight preference. The free enthalpy of rotation, calculated approximately, is between 56.0 (1m) and 73.7 kJ/mol (1r).

Fibrinolytic Agents↗
PubMed2003

Synthesis and antimicrobial activity of [2-[2-(N, N-disubstituted thiocarbamoyl-sulfanyl)-acylamino] thiazol-4-yl]acetic acid ethyl esters.

[2-[2-(N, N-Disubstituted thiocarbamoyl-sulfanyl)acylamino ]thiazol-4-yl]acetic acid ethyl esters (3a-x) were synthesized by the reaction of potassium salts of N, N-disubstituted dithiocarbamoic acids with [2-(2-chloroalkanoyl)amino-thiazol-4-yl]acetic acid ethyl esters. The structures of the synthesized compounds were confirmed by elemental analyses, UV, IR, (1)H-NMR, and EI mass spectral data. The antimicrobial activities of all the compounds were investigated by microbroth dilution technique using Mueller-Hinton broth and Mueller-Hinton agar. In this study, Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 8739, Klebsiella pneumoniae ATCC 4352, Pseudomonas aeruginosa AT CC 1539, Salmonella typhi, Shigella flexneri, Proteus mirabilis ATCC 14153 and Candida albicans ATCC10231 were used as test microorganisms. Among the tested compounds 3a, d, e, f, h, k, w activity against S. epidermidis ATCC 12228 (MIC: 156 mg/L, 78 mg/L, 62.5 mg/L, 78 mg/L, 62.5 mg/L, 312 mg/L, 250 mg/L, respectively), compound 3d had some activity against S. aureus ATCC 6538 (MIC: 156 mg/L) and C. albicans ATCC 10231(MIC: 156 mg/L). Compounds 3l, 3x also evaluated for antituberculosis activity against Mycobacterium tuberculosis H37Rv using the BACTEC 460 radiometric system and BACTEC 12B medium. The preliminary results indicated that all of the tested compounds were inactive against the test organism.

Anti-Bacterial Agents↗
PubMed1986

Thiazole orange: a new dye for reticulocyte analysis.

The purpose of this study was to find a 488-nm excitable fluorescent dye for reticulocyte analysis by the use of fluorescence activated cell cytometry. The chemical structure of thioflavin T, a dye used for reticulocyte analysis with 457-nm excitation, was used as a model. Several dyes were synthesized and evaluated by quantum yield determination, fluorescence microscopy, and flow cytometry. The best results were obtained with a dye we have named "thiazole orange"; analysis of several blood samples with thiazole orange gave a correlation coefficient of 0.97 as compared to a manual determination of reticulocyte percentage.

Benzothiazoles↗
PubMed1986

The direct-acting mutagenicity of nitroimidazo[2,1-b]thiazoles in Salmonella typhimurium.

A series of nitroimidazo[2,1-b]thiazole derivatives was investigated for direct-acting mutagenic potency with the Salmonella assay. All of the nine derivatives tested were mutagenic. The compounds induced predominantly base displacements resulting in frame-shift mutations. The mutagenic activity did not require the S9 fraction but was largely dependent on "classical" bacterial nitroreductase. The primary basis of the mutagenic activity of nitroimidazo[2,1-b]thiazoles appears to be a reduction of the nitro-function to the corresponding hydroxylamine. Mutagenicity seems to be paralleled by an increase of the nitro groups: dinitroderivatives were more active than nitroderivatives. Other electrophiles and sterically constrained nitro groups could account for differences in genotoxicity.

Mutagenicity Tests↗
PubMed1991

4- or 5- (omega-aminoalkyl) thiazoles and derivatives; new selective H2-receptor agonists.

It is well known that both histamine and dimaprit show moderate H2-receptor agonistic activity (guinea pig right atrium). Quantum chemical calculations indicated that 2-aminothiazole derivatives that might be regarded as cyclic dimaprit analogues, should possess H2-receptor agonistic activity as well. In the present study a series of 4- or 5-(omega-aminoalkyl) thiazoles has been synthesized, showing a moderate to strong H2-receptor agonistic activity as compared to histamine whereas no activity on H1- and H3-receptors could be detected. In contrast to histamine and derivatives, which are supposed to "trigger" the H2-receptor via a tautomeric shift involving two protons viz. one proton of the active site of the receptor and one proton of the heteroaromatic ring system, the thiazole derivatives seem to stimulate the H2-receptor via a one proton mechanism. In a series of impromidine analogues the 3- [4(5)-imidazolyl]propyl moiety was replaced by the more H2-receptor specific 3-(4- or 5-thiazolyl)propyl fragment resulting in potent and selective full H2-receptor agonists.

Amines↗
PubMed1989

H2-receptor antagonist activity of N-methylthiourea, N-cyano-N'-methylguanidine, N-cyanoamidine, N-carbamoylamidine and N-sulfamoylamidine 5-substituted thiazole derivatives on guinea-pig atria.

The H2-antagonist activity of thiazole derivatives, substituted on position 5 with urea-equivalent groups, has been tested on guinea-pig isolated atria stimulated by dimaprit. By comparing the activities of the 2,5-disubstituted thiazole derivatives with those of the corresponding 2,4-disubstituted derivatives it can be seen that the side-chain position is critical to activity and differently influences activity in the various series. The heteroaromatic ring atom sequence N-C-S-C-side chain is always associated with a low antagonist activity.

Animals↗
PubMed2004

Synthesis and study of antibacterial and antifungal activities of novel 2-[[(benzoxazole/benzimidazole-2-yl)sulfanyl] acetylamino]thiazoles.

Several 2-[[(benzoxazole/benzimidazole-2-yl)sulfanyl]acetylamino]thiazoles derivatives were synthesized by reacting 4-substituted-2-(chloroacetylamino)thiazoles with benzoxazole/benzimidazole-2-thioles in acetone and in the presence of K2CO3. The chemical structures of the compounds were elucidated by IR, 1H-NMR, and FAB(+)-MS spectral data. Their antimicrobial activities against Micrococcus luteus (NRLL B-4375), Bacillus cereus (NRRL B-3711), Proteus vulgaris (NRRL B-123), Salmonella typhimurium (NRRL B-4420), Staphylococcus aureus (NRRL B-767), Escherichia coli (NRRL B-3704), Candida albicans and Candida globrata (isolates obtained from Osmangazi Uni. Fac.of Medicine) were investigated and in this investigation, a significant level of activity was illustrated.

Anti-Bacterial Agents↗
PubMed2000

Synthesis and antibacterial activity of some new non-proteinogenic amino acids containing thiazole residues.

Some new thioamides and thiazoles have been synthesized using canavanine, S-cysteine, homo-S-cysteinesulfonamides and their N-omega aminoethylated derivatives as adducts in order to investigate the structure-antimicrobial activity relationships. The compounds showed substantial antibacterial activity in vitro against various gram-positive (Staphylococcus aureus, Bacillus cereus etc.) and gram-negative (Escherichia coli, Proteus vulgaris etc.) bacteria. These findings indicate that the presence of the thiazole residue is an essential factor for the antibacterial effect.

Amino Acids↗
PubMed2006

Structure-based 3D-QSAR studies on thiazoles as 5-HT3 receptor antagonists.

Structure-based 3D-QSAR studies were performed on 20 thiazoles against their binding affinities to the 5-HT(3) receptor with comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). The thiazoles were initially docked into the binding pocket of a human 5-HT(3A) receptor homology model, constructed on the basis of the crystal structure of the snail acetylcholine binding protein (AChBP), using the GOLD program. The docked conformations were then extracted and used to build the 3D-QSAR models, with cross-validated r2omega values 0.785 and 0.744 for CoMFA and CoMSIA, respectively. An additional five molecules were used to validate the models further, giving satisfactory predictive r2 values of 0.582 and 0.804 for CoMFA and CoMSIA, respectively. The results would be helpful for the discovery of new potent and selective 5-HT(3) receptor antagonists.

Amino Acid Sequence↗
PubMedDate not supplied

Mutagenic activity of 5 thiazole compounds in the Salmonella/microsome and mouse lymphoma TK+/- assays.

To aid in the selection of chemical candidates for in vivo tests, the mutagenicity of 5 thiazole compounds was evaluated in the Salmonella plate incorporation assay and mouse lymphoma L5178Y TK+/- assay. Two of the compounds, 2-thiazolamine and 3-methyl-5-isothiazolamine, were positive in both assays; and one, thiazole, was negative. With the other 2 compounds the results were nonconcordant: 5-phenyl-2,4-thiazolediamine was negative in the Salmonella assay but positive in the mouse lymphoma assay, and C.I. Basic Red 29 was positive in the Salmonella assay while the response in the mouse lymphoma assay was considered equivocal.

Animals↗
PubMed2004

Effects of new ubiquinone-imidazo[2,1-b]thiazoles on mitochondrial complex I (NADH-ubiquinone reductase) and on mitochondrial permeability transition pore.

In this work we describe the synthesis of a series of imidazo[2,1-b]thiazoles and 2,3-dihydroimidazo[2,1-b]thiazoles connected by means of a methylene bridge to CoQ(0). These compounds were tested as specific inhibitors of the NADH:ubiquinone reductase activity in mitochondrial membranes. The imidazothiazole system when bound to the quinone ring in place of the isoprenoid lateral side chain, may increase the inhibitory effect (with an IC(50) for NADH-Q(1) activity ranging between 0.25 and 0.96 microM) whereas the benzoquinone moiety seems to lose the capability to accept electrons from complex I as indicated by very low maximal velocity elicited by the compounds tested. Moreover the low rotenone sensitivity for almost all of these compounds suggests that they are only partially able to interact with the physiological ubiquinone-reduction site. The compounds were investigated for the capability of increasing the permeability transition of the inner mitochondrial membrane in isolated mitochondria. Unlike CoQ(0), which is considered a mitochondrial membrane permeability transition inhibitor, the new compounds were inducers.

Animals↗
PubMed2005

QSAR study on thiazole and thiadiazole analogues as antagonists for the adenosine A1 and A3 receptors.

Thiazole and thiadiazole analogues have been recently proposed as a novel promising class of adenosine A1 and A3 receptor antagonists. When appropriately modified, they show selectivity toward A1 or A3 receptors, which results in a variety of therapeutic potentialities of these ligands. In this work, we carried out a QSAR study on thiazole and thiadiazole analogues as antagonists for adenosine A1 and A3 receptors. To develop reliable models, we focused attention on any possible pitfalls of each step of QSAR process and approached each stage following accurate procedures. Application of datasets by using CODESSA software led to QSAR equations based on three and four descriptors for the adenosine A1 and A3 receptor ligands, respectively. The obtained models allowed us to understand the main structural features that strongly correlate with the target property.

Adenosine A1 Receptor Antagonists↗
PubMed2004

Synthesis and structure-activity relationships of uracil derived human GnRH receptor antagonists: (R)-3-[2-(2-amino)phenethyl]-1-(2,6-difluorobenzyl)-6-methyluracils containing a substituted thiophene or thiazole at C-5.

The synthesis of a series of (R)-3-[2-(2-amino)phenethyl]-1-(2,6-difluorobenzyl)-6-methyluracils containing a substituted thiophene or thiazole at C-5 is described. SAR around C-5 of the uracil led to the discovery that a 2-thienyl or (2-phenyl)thiazol-4-yl group is required for optimal receptor binding. The best compound from the series had a binding affinity of 2 nM (K(i)) for the human GnRH receptor. A novel and convenient preparation of N-1-(2,6-difluorobenzyl)-6-methyluracil is also described.

Humans↗