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PubMed1998

Development of dual-acting agents for thromboxane receptor antagonism and thromboxane synthase inhibition. 2. Design, synthesis, and evaluation of a novel series of phenyl oxazole derivatives.

Synthesis and initial in vitro evaluation of a novel series of phenyl oxazole derivatives are described. An SAR study of the novel dual-acting TRA/TSI agent has revealed that the lipophilicity of the oxazole amide substituents greatly influences the TRA activity but not the TSI. The chain length of the alkenoic acid side chain affects both TRA and TSI. The optimal chain length for the combined activities was found to be n = 4 (heptenoic acid).

Drug Design↗
PubMed2005

Deprotonation of benzoxazole and oxazole using lithium magnesates.

The first deprotonations of oxazole and benzoxazole using lithium magnesates are described. The reactions occurred in tetrahydrofuran at room temperature using 1/3 equiv of lithium tributylmagnesate. As 2-lithiooxazole and 2-lithiobenzoxazole, lithium tri(2-oxazolyl)magnesate and lithium tri(2-benzoxazolyl)magnesate very rapidly and completely isomerized to the more stable 2-(isocyano)enolate and 2-(isocyano)phenolate type structures, respectively, a result shown by NMR analysis. The isolation of 2-substituted oxazoles and benzoxazoles in medium to good yields after electrophilic trapping was interpreted in two ways: (1) the equilibration between the open and closed structures is faster than the trapping of the open isomers, and the closed isomers are more reactive than the open ones, or (2) the open isomers react with electrophiles in a intramolecular Passerini type reaction. The nonreactivity of the 2-(isocyano)enolate type structure toward anisaldehyde in the absence of lithium bromide makes the intramolecular Passerini type reaction more plausible.

Journal Article↗
PubMed2004

Photoinduced [4 + 4] cycloadditions of o-quinones with oxazoles.

[reaction: see text] Photocycloadditions of 9,10-phenanthraquinone (PQ) with oxazoles (1a and 1b) gave [4 + 4] products 2 with the O=C-C=O functionality in PQ and the 2-azadiene moiety in oxazole as 4pi addends. Photoreactions of 1-acetylisatin (IS) with 1a, 1c, and 1d gave [4 + 4] product A, which underwent further [2 + 2] reactions with another (3)IS to furnish 5. These regioselective and diastereoselective [4 + 4] photocycloadditions are rationalized by the intervening of the key conformers for ISC and bond formation of the most stable 1,6-diradical intermediates.

Journal Article↗
PubMed1998

1H NMR studies of the bis-intercalation of a homodimeric oxazole yellow dye in DNA oligonucleotides.

We have used one and two dimensional 1H NMR spectroscopy to characterize the binding of a homodimeric oxazole yellow dye, 1,1'-(4,4,8,8-tetramethyl-4,8-diaza-undecamethylene)-bis-4-( 3-methyl-2,3-dihydro-(benzo-1,3-oxazole)-2-methylidene)-quinoliniu m tetraiodide (YOYO), to oligonucleotides containing the (5'-CTAG-3')2 and the (5'-CCGG-3')2 binding sites in either different oligonucleotides or in the same oligonucleotide. YOYO bis-intercalates strongly in all the oligonucleotides used and binds preferentially to a (5'-CTAG-3')2 binding site in the oligonucleotide d(CGCTAGCG)2 (1). YOYO also binds preferentially to a (5'-CCGG-3')2 sequence in the oligonucleotide d(CGCCGGCG)2 (2) but slightly less favorably than to the (5'- CTAG-3')2 sequence in 1. The binding of YOYO to the d(CGCTAGCCGGCG):d(CGCCGGCTAGCG) (3) oligonucleotide, containing two preferential binding sites, was also examined. YOYO forms mixtures of 1:1 and 1:2 complexes with oligonucleotide 3 in ratios dependent on the relative amount of YOYO and the oligonucleotides in the sample. The binding of YOYO to the oligonucleotide 3 occur sequence selective in the (5'-CTAG-3')2 site and the (5'- CCGG-3')2 site. We have also used two dimensional 1H NMR spectroscopy to determine the solution structure of the DNA oligonucleotide d(5'-CGCTAGCG-3')2 complexed with YOYO. The determination of the structure was based on a total relaxation matrix analysis of the NOESY cross peaks intensities. DQF-COSY spectra were used to obtain coupling constants for the deoxyribose ring protons. The coupling constants were transformed into angle estimates. The NOE derived distance and dihedral restraints were applied in restrained molecular dynamics calculations. Twenty final structures each were generated for the YOYO-complex from both A-form and B-form dsDNA starting structures giving a total of 40 final structures. Since many NOE contacts were observed between YOYO and dsDNA the resulting structure has a fairly high resolution and allows determination of local features in the dsDNA structure after YOYO binding. The root-mean-square (rms) deviation of the coordinates for the forty structures of the complex was 0.39 A. The local DNA structure is distorted in the complex. The helix is unwound by 106 degrees and has an overall helical repeat of 13 base pairs caused by the bis-intercalation of YOYO. The polypropylene amine linker chain is located in the minor groove of dsDNA. Even though the YOYO chromophore contains an oxygen atom instead of the larger sulphur atom in the corresponding compound, TOTO, the structures establish that YOYO require more space than TOTO in the intercalation sites. This is probably caused by the more rigid and planar chromophores in YOYO compared to TOTO.

Benzoxazoles↗
PubMed1998

Synthesis and biological evaluation of a series of substituted pyrazolo[3,4-d]-1,2,3-triazoles and pyrazolo[3,4-d]oxazoles.

In view of the biological relevance of triazole-based heterocyclic structures as antifungal, antiviral, and antitumor agents, we have synthesized a series of substituted pyrazolo[3,4-d]-1,2,3-triazoles (2e-h, 2j, 4b) which we evaluated for their cytostatic and antiviral (HIV-1 included) activity and for their capability to inhibit the multiplication of various human pathogenic fungi and bacteria. Moreover, the biological activities of a few compounds, namely pyrazolo[3,4-d]oxazoles (3a-e) and pyrazolo[3,4-d]-1,2,3-triazoles (2a-d, 4a, 5), previously obtained by us but not investigated for their biological activity, were also studied. Only compounds 3a-e were endowed with a significative antiproliferative activity on the human lymphoblastoid cell line MT-4 cells. All pyrazole derivatives proved ineffective in protecting cell cultures against the HIV-1-induced cytopathogenicity, and none of the compounds was active against the bacteria and fungi tested.

Anti-Bacterial Agents↗
PubMed2006

Preclinical pharmacokinetics and metabolism of 6-(4-(2,5-difluorophenyl)oxazol-5-yl)-3-isopropyl-[1,2,4]-triazolo[4,3-a]pyridine, a novel and selective p38alpha inhibitor: identification of an active metabolite in preclinical species and human liver microsomes.

The disposition of 6-(4-(2,5-difluorophenyl)oxazol-5-yl)-3-isopropyl-[1,2,4]-triazolo[4,3-a]pyridine (1), a potent and selective inhibitor of mitogen activated protein (MAP) kinase p38alpha, was characterized in several animal species in support of its selection for preclinical safety studies and potential clinical development. 1 demonstrated generally favorable pharmacokinetic properties in all species examined. Following intravenous (i.v.) administration, 1 exhibited low volumes of distribution at steady state (Vd(ss)) ranging from 0.4-1.3 l/kg (2.4-26 l/m(2)) in the rat, dog and monkey. Systemic plasma clearance was low in cynomolgus monkeys (6.00 ml/min/kg, 72.0 ml/min/m(2)) and Sprague-Dawley rats (7.65+/-1.08 ml/min/kg, 45.9+/-6.48 ml/min/m(2) in male rats and 3.15+/-0.27 ml/min/kg, 18.9+/-1.62 ml/min/m(2) in female rats) and moderate in beagle dogs (12.3+/-5.1 ml/min/kg, 246+/-102 ml/min/m(2)) resulting in plasma half-lives ranging from 1 to 5 h in preclinical species. Moderate to high bioavailability of 1 was observed in rats (30-65%), dogs (87%) and monkeys (40%) after oral (p.o.) dosing consistent with the in vitro absorption profile of 1 in the Caco-2 permeability assay. In rats, the oral pharmacokinetics were dose dependent over the dose range studied (5, 50 and 100 mg/kg). The principal route of clearance of 1 in rat, dog, monkey and human liver microsomes and in vivo in preclinical species involved oxidative metabolism mediated by cytochrome P450 enzymes. The major metabolic fate of 1 in preclinical species and humans involved hydroxylation on the isopropyl group to yield the tertiary alcohol metabolite 2. In human liver microsomes, this transformation was catalysed by CYP3A4 as judged from reaction phenotyping analysis using isozyme-specific inhibitors and recombinant CYP enzymes. Metabolite 2 was also shown to possess inhibitory potency against p38alpha in a variety of in vitro assays. 1 as well as the active metabolite 2 were moderately to highly bound to plasma proteins (f(u) approximately 0.1-0.33) in rat, mouse, dog, monkey and human. 1 as well as the active metabolite 2 did not exhibit competitive inhibition of the five major cytochrome P450 enzymes namely CYP1A2, 2C9, 2C19, 2D6 and 3A4 (IC(50)>50 microM). Overall, these results indicate that the absorption, distribution, metabolism and excretion (ADME) profile of 1 is relatively consistent across preclinical species and predict potentially favorable pharmacokinetic properties in humans, supporting its selection for toxicity/safety assessment studies and possible investigations in humans as an anti-inflammatory agent.

Administration, Oral↗
PubMedDate not supplied

Fluorescence and chemiluminescence detection of oxazole-labelled amines and thiols.

Fluorescence and chemiluminescence analyses of amino acids and thiols derivatized with 2-fluoro-4,5-diphenyloxazole (DIFOX) and 2-chloro-4,5-bis(p-N,N-dimethylaminosulphonylphenyl)oxazole (SAOX-Cl) were investigated. Thirteen diphenyloxazole (DIOX)-derivatized amino acids were separated within 38 min by a linear gradient elution from 100% A [0.05 M phosphate (pH 7.0): CH3CN (75:25)] to 100% B [0.05 M phosphate (pH 7.0):CH3CN (1:1)] over 30 min and an isocratic elution of 100% B for 30 min. The detection limits (S/N = 2) with fluorescence detection were in the range of 19-64 fmol. Thiols derivatized with SAOX-Cl were separated by an isocratic elution using 0.1 M H3PO4:CH3CN (65:35) and detected fluorimetrically. The detection limits (S/N = 2) of reduced glutathione, N-acetylcysteine, 2-mercaptopropionylglycine, cysteine, homocysteine and captopril were 1.2, 1.5, 1.9, 5.7, 6.4 and 7.9 fmol, respectively. Peroxyoxalate chemiluminescence (CL) intensities of sulphonyl-5-N,N-dimethylaminonaphthalene (DNS), SAOX and DIOX derivatives were compared using three different oxalate esters (DFPO, TCPO and TDPO) by flow injection analysis. The relative chemiluminescence intensity (RCL) of SAOX-proline and DIOX-proline were 76-80% and 19-25% of DNS-proline (100%), respectively. Other SAOX and DIOX derivatives showed lower CL intensities (< 12%). Extremely low CL intensities were obtained for the fluorescent tagging reagents (< 0.11%) and their hydrolysis products (< 0.80%). Secondary amino acids and peptides, derivatized with DIFOX in aqueous media at room temperature for 1 h, were detected using DFPO/H2O2. TCPO/H2O2 and TDPO/H2O2 after separation by high performance liquid chromatography.(ABSTRACT TRUNCATED AT 250 WORDS)

Amines↗
PubMed2026

Unlocking antifungal mechanisms of natural 3-(oxazole-5-yl) indole compound derived from Streptomyces syringium against plant gray mold caused by Botrytis cinerea.

BACKGROUND: Plant fungal diseases cause significant agricultural losses, and Streptomyces-derived antifungal compounds offer a promising biocontrol strategy. This study aimed to isolate and characterize bioactive metabolites from Streptomyces syringium LZ036 and evaluate their activity and mechanism of action against Botrytis cinerea. RESULTS: A strain LZ036 with broad-spectrum antifungal activity was identified as Streptomyces syringium. The 3-(oxazole-5-yl) indole compound NL3 isolated from this strain exhibited potent broad-spectrum antifungal activity, especially against Botrytis cinerea. Compound NL3 inhibited fungal growth and development by inducing severe oxidative damage and membrane disruption. And it could trigger jasmonic acid (JA)-dependent induced systemic resistance (ISR) in plants. Transcriptomic analysis of compound NL3-treated Botrytis cinerea revealed genome-wide transcriptional alterations, including disruption of energy metabolism and mitochondrial function. Key genes related to mitogen-activated protein kinase (MAPK) signaling pathway down-regulated significantly, among which the catalytic S_TKc domain of Bcste7 exhibited a predicted interaction with compound NL3 through hydrophobic interactions and hydrogen bonding. CONCLUSION: The Streptomyces syringium-derived compound NL3 shows high potential as a green fungicide, acting through multiple mechanisms. These findings advance the development of Streptomyces-based antifungal agents. &#xa9; 2026 Society of Chemical Industry.

3&#x2010;(oxazole&#x2010;5&#x2010;yl) indole compo↗
PubMed1994

Oxazole, pyrazole and piperidine derivatives having an o-hydroxyaryl moiety with anticipated molluscicidal activity.

The condensation reactions of hippuric acid and its furyl derivative with salicylaldehydes or that of salicylhippuric acid analogues with furaldehyde led to the corresponding oxazoles. These were subsequently treated with hydrazine hydrate, hydroxylamine or subjected to alkaline hydrolysis to yield new o-hydroxyaryl or salicyl containing derivatives. 5-Substituted salicylanilides were treated with piperidine and formaldehyde in a Mannich type reaction affording the corresponding 3-(N-piperidinomethyl) salicylanilides. It was noticed that the presence of an electron donating group in position 3 in the salicylanilide moiety decreases the molluscicidal activity.

Animals↗
PubMed2006

Synthesis and G-quadruplex stabilizing properties of a series of oxazole-containing macrocycles.

The synthesis of 24-membered macrocycles containing four, six, and seven oxazole moieties is described. Selected compounds were evaluated for their ability to specifically bind and stabilize G-quadruplex DNA and for cytotoxic activity. An unexpected oxidative cleavage reaction afforded a macrocyclic imide that was also evaluated for G-quadruplex stabilizing and cytotoxic activity.

DNA↗
PubMed2006

Structure-activity relationships of triazolopyridine oxazole p38 inhibitors: identification of candidates for clinical development.

The synthesis, structure-activity relationship, in vivo activity, and metabolic profile for a series of triazolopyridine-oxazole based p38 inhibitors are described. The deficiencies of the lead structure in the series, CP-808844, were overcome by changes to the C4 aryl group and the triazole side-chain culminating in the identification of several potential clinical candidates.

Chemistry, Pharmaceutical↗
PubMed2006

Discovery and structure-activity relationship of 2-phenyl-oxazole-4-carboxamide derivatives as potent apoptosis inducers.

As a continuation of our efforts to discover novel apoptosis inducers as anticancer agents using a cell-based caspase HTS assay, 2-phenyl-oxazole-4-carboxamide derivatives were identified. The structure-activity relationships of this class of molecules were explored. Compound 1k, with EC(50) of 270 nM and GI(50) of 229 nM in human colorectal DLD-1 cells, was selected and demonstrated the ability to cleave PARP and displayed DNA laddering, the hallmarks of apoptosis. Compound 1k showed 63% tumor growth inhibition in human colorectal DLD-1 xenograft mouse model at 50 mpk, bid.

Amides↗
PubMed2004

In vitro scavenging activity for reactive oxygen and nitrogen species by nonsteroidal anti-inflammatory indole, pyrrole, and oxazole derivative drugs.

This study was undertaken to evaluate the scavenging activity for reactive oxygen species (ROS) and reactive nitrogen species (RNS) by several nonsteroidal anti-inflammatory drugs (NSAIDs), namely indole derivatives (indomethacin, acemetacin, etodolac), pyrrole derivatives (tolmetin and ketorolac), and an oxazole derivative (oxaprozin). The inhibition of prostaglandin synthesis constitutes the primary mechanism of the anti-inflammatory action of these drugs. Nevertheless, it has been suggested that the anti-inflammatory activity of NSAIDs may be also partly due to their ability to scavenge ROS and RNS and to inhibit the respiratory burst of neutrophils triggered by various activator agents. Thus, the scavenging activity of these NSAIDs was evaluated against an array of ROS (O(2)(-), HO, HOCl, and ROO) and RNS (NO and ONOO(-)) using noncellular in vitro systems. The results obtained demonstrated that tolmetin, ketorolac, and oxaprozin were not active against O(2)(-), while acemetacin, indomethacin, and etodolac exhibited concentration-dependent effects. Oxaprozin was also the least active scavenger for HO, among all the tested NSAIDs shown to be active. The scavenging effect for HOCl was not observed for any of the tested NSAIDs. The ROO was effectively scavenged by etodolac, with the other tested NSAIDs being much less active. NO and ONOO(-) were scavenged by all the tested NSAIDs. These effects may strongly contribute to the anti-inflammatory therapy benefits that may be attained with some of the studied NSAIDs.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Substituted oxazole benzenesulfonamides as potent human beta3 adrenergic receptor agonists.

As a part of our investigation into the development of orally bioavailable beta3 adrenergic receptor agonists, we have identified a series of substituted oxazole derivatives that are potent beta3 agonists with excellent selectivity against other beta receptors. Several of these compounds showed excellent oral bioavailability in dogs. One example, cyclopentylethyloxazole 5f is a potent beta3 agonist (EC50 = 14 nM, 84% activation) with 340-fold and 160-fold selectivity over beta1 and beta2 receptors, respectively, and has 38% oral bioavailability in dogs.

Adrenergic beta-3 Receptor Agonists↗
PubMed2001

2,4-Disubstituted oxazoles and thiazoles as latent pharmacophores for diacylhydrazine of SC-51089, a potent PGE2 antagonist.

8-Chlorodibenz[b,f][1,4]oxazepine-10(11H)-carboxylic acid, 2-[1-oxo-3-(4-pyridinyl)propyl]hydrazide, monohydrochloride (1, SC-51089) is a functional PGE2 antagonist selective for the EP1 receptor subtype with antinociceptive activity. Analogues of SC-51089, in which the diacylhydrazine moiety has been replaced with 2,4-disubstituted-oxazoles and-thiazoles, are described.

Dinoprostone↗
PubMed1998

Alpha 1-adrenergic receptor subtype determinants for 4-piperidyl oxazole antagonists.

Mutational studies in conjunction with ligand binding assays were used to examine the basis of alpha1-adrenergic receptor subtype selectivity for a series of 4-piperidyloxazole antagonists. A set of chimeric alpha 1A receptors were created by systematically substituting individual transmembrane domains from alpha 1D adrenergic receptors. The oxazole antagonists exhibited significant reductions in affinity against the receptor construct alpha 1A/D(TM2), and moderate reductions in affinity versus constructs alpha 1A/D(TM5), alpha 1A/B(TM5), and alpha 1A/D(TM6). Antagonist affinities for these chimeras exceeded those found for wild type alpha 1D and alpha 1B. Site-directed mutagenesis methods were then used to explore the role that individual residues in TM2 and TM5 play in ligand binding affinity and selectivity. These studies revealed that mutations at position 86 in the second transmembrane domain and position 185 in the fifth transmembrane domain of the alpha 1A receptor have a major impact on receptor subtype selectivity.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1998

ATP/GTP hydrolysis is required for oxazole and thiazole biosynthesis in the peptide antibiotic microcin B17.

In the maturation of the Escherichia coli antibiotic Microcin B17, the product of the mcbA gene is modified posttranslationally by the multimeric Microcin synthetase complex (composed of McbB, C, and D) to cyclize four Cys and four Ser residues to four thiazoles and four oxazoles, respectively. The purified synthetase shows an absolute requirement for ATP or GTP in peptide substrate heterocyclization, with GTP one-third as effective as ATP in initial rate studies. The ATPase/GTPase activity of the synthetase complex is conditional in that ADP or GDP formation requires the presence of substrate; noncyclizable versions of McbA bind to synthetase, but do not induce the NTPase activity. The stoichiometry of ATP hydrolysis and heterocycle formation is 5:1 for a substrate that contains two potential sites of modification. However, at high substrate concentrations (>50Km) heterocycle formation is inhibited, while ATPase activity occurs undiminished, consistent with uncoupling of NTP hydrolysis and heterocycle formation at high substrate concentrations. Sequence homology reveals that the McbD subunit has motifs reminiscent of the Walker B box in ATP utilizing enzymes and of motifs found in small G protein GTPases. Mutagenesis of three aspartates to alanine in these motifs (D132, D147, and D199) reduced Microcin B17 production in vivo and heterocycle formation in vitro, suggesting that the 45 kDa McbD has a regulated ATPase/GTPase domain in its N-terminal region necessary for peptide heterocyclization.

Adenosine Triphosphatases↗