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A series of azole derivatives of 1,4-benzothiazine 7-14 was synthesized and evaluated for the in vitro and in vivo activity against Candida albicans. Secondary alcohol 10 and its ether derivative 13 showed very good efficacy against systemic candidiasis in a murine experimental model.
The somatic muscle cells of the parasitic nematode Ascaris suum possess GABA receptors that gate chloride conductances in a similar fashion to the mammalian GABAA receptor subtype. These receptors mediate muscle relaxation and are the site of action of the anthelmintic piperazine. The properties of this receptor differ from the properties of the GABA-gated chloride receptors in the mammalian host, in particular they are not as sensitive to mammalian GABA receptor antagonists such as bicuculline and picrotoxin. Using two-electrode intracellular electrophysiological recording techniques from Ascaris muscle cells, we have tested the potency of a series of azole derivatives for their ability to block the chloride-dependent GABA response. The lead compound, SN606078, 2-(2,6-dichloro-4-trifluoromethylphenyl)-4-(4,5-dicyano-1H-imidazo l-2-yl)-2H- 1,2,3-triazole, and 4 structurally related compounds reversibly blocked the conductance increase elicited by 30 microM GABA with IC50s of less than 10 microM. SN606078 (10 microM) decreased the slope of the dose-response curve for GABA, suggesting a non-competitive mechanism of action. In two-electrode voltage clamp experiments, 10 microM SN606078 blocked the outward current elicited by 20 microM GABA in a voltage-dependent manner with 72 +/- 2% inhibition at -20 mV and 49 +/- 6% inhibition at -40 mV. These observations indicate that SN606078 may act as an open-channel blocker of the GABA-gated chloride channel in A. suum.
A combination between 3D-QSAR and molecular mechanics (MM)-docking study was used as a tool to detail and model the mechanism of action of 46 antifungal azoles. Two methods of alignment of the ligands were performed: (i) alignment of the main skeleton without substituents and (ii) alignment of a defined substructure. The best model is characterized by q(2) with the values of 0.70 for yeastlike (yeast), 0.66 for filamentous fungi, and 0.70 for the selectivity against filamentous fungi. 3D-QSAR regression maps derived from six models were used to identify the regions responsible for the differences in the compounds activity against yeast and filamentous fungi. The binding energy of the important substructures (Local Binding Energy-LBE) and its standard deviation were calculated in order to demonstrate quantitatively the contribution of substituents reflecting the diversity of the antifungal activity. The comparisons of these results with the same regions of the contour maps indicated a good correspondence between the 3D-QSAR and MM (LBE) approaches allowing association between the maps and the participating residues in the active sites of P450DM of C. albicans and A. fumigatus. The pi-pi interactions of two or more aromatic groups of the ligands with Phe228 and Tyr132 prove to be most important for the differences in activity against C. albicans. In A. fumigatus there was a better occupation of the inner central I-spiral in the areas around the heme. For the activity against A. fumigatus the pi-pi interactions of aromatic groups of the compounds with Phe509, Phe228, and Tyr132 are significant for the activity.
Three new derivatives of the cytotoxic azole-bridged dinuclear platinum(II) complex [(cis-Pt(NH3)2)2(mu-OH)(mu-pz)][NO3]2 (1) have been prepared and structurally characterized. Their formulas are [(cis-Pt(NH3)2)2(mu-OH)(mu-1,2,3-ta)][NO3]2 (2) (1,2,3-ta = 1,2,3-triazolate), [(Pt(R,R-dach))(mu-OH)(mu-pz)(Pt(S,S- dach))][NO3]2 (3) (dach = 1,2-diaminocyclohexane, pz = pyrazolate), and [(Pt(R,R-dach))(mu-1,2,3- ta)2(Pt(S,S-dach))][NO3]2 (4). The compounds were characterized by 1H, 13C, and 195Pt NMR spectroscopy, and elemental analysis, and their crystal structures were determined. Relevant data for 2: triclinic, space group P1, a = 8.5225(15) A, b = 9.1977(18) A, c = 9.9771(7) A, alpha = 66.988(10) degrees, beta = 75.423(9) degrees, gamma = 67.321(13) degrees, Z = 2. 3: orthorhombic, space group Pca2(1), a = 17.7653(3) A, b = 12.4076(3) A, c = 10.7091(3) A, Z = 4. 4: orthorhombic, space group Pbca, a = 13.8944(1) A, b = 17.8668(1) A, c = 20.7647(2) A, Z = 8. In the crystal structures of 2, and 3, the intramolecular distances between the two Pt atoms are 3.4411(6) and 3.4873(5) A, and the dihedral angles between the platinum coordination planes are 14.1(3) and 9.3(4) degrees, respectively. In 2, an intramolecular hydrogen bond is observed between N9 of the ammine ligand and the noncoordinated nitrogen atom (N3) of the triazole ring (N9...N3: 2.962(10) A). 4 has a boat-form structure, and the two coordination planes cross at 83.64(10) degrees. A cytotoxicity assay of these dinuclear platinum(II) compounds on human tumor cell lines was performed. In most of the cell lines, 1 and 2 showed much higher cytotoxicity than those of cisplatin. On the other hand, 3 was found to be moderately active, and 4 was found only marginally cytotoxic. Implications of these findings are discussed in the context of a structure-activity relationship.
A series of azole derivatives carrying an N-acylmorpholine ring are described. The compounds were chemically designed to simulate the lanosterol D ring, taking advantage of the conformational preferences of 2-alkyl-1-acylmorpholines. Three structural variables, the nature of the N-benzoyl group, the phenyl substituents, and the degree of oxidation at carbon 2 of the morpholine, were optimized for maximum activity. Only the (5R,6R) isomers showed antifungal activity. Cyclic hemiacetal (-)-39a (UR-9746) and cyclic ether (-)-41 (UR-9751) were selected for further development. In vitro, (-)-41 was clearly more active than (-)-39a and somewhat less active than the acyclic counterpart (-)-7. In vivo activity was assessed by a systemic (mouse) and a vaginal (rat) candidosis model. In the former, (-)-39a, (-)-41, and (-)-7 at 1 mg/kg given 1, 4, and 24 h postinfection displayed 90-100% protection from mortality on day 9. Compound (-)-39a was slightly more potent than (-)-41 and similar in potency to (-)-7. The three compounds were superior in potency to fluconazole and similar in potency in SCH-42427 in this test. In the vaginal model, (-)-39a and (-)-41 given daily during 3 days after infection at 0.5 mg/kg showed high levels of protection on days 10 and 15. At 0.25 mg/kg, (-)-39a was slightly more potent than SCH-42427 and (-)-7 and superior in potency to (-)-41 and fluconazole in this model. Preliminary 28-day toxicity tests at 100 mg/kg/day po in rats indicated no or very mild adverse effects for the two UR compounds.
A series of 6-fluoro- and 6,8-difluoro-7-(azole substituted)-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids were prepared. Structure-activity relationship studies indicated that the antibacterial potency was better when the 6,8-substituents were fluorine atoms and the 7-substituent was either 1-imidazolyl, 20, or 4-methyl-1-imidazolyl, 25. From the results of studies on pharmacokinetic profile and toxicity, 20 and 25 were found to possess excellent antibacterial activities and to show high blood levels after oral administration to mice with low toxicity.
Three-dimensional (3D) quantitative structure-activity relationship (QSAR) and structure-activity relationship (SAR) analyses were applied concurrently to a data set of highly selective estrogen receptor beta (ERbeta) agonists. The data set consisted of diphenolic azoles characterized by similar structural skeletons but with different binding modes to the estrogen receptor site. Models were developed separately with respect to the relative binding affinities (RBAs) to ERalpha and ERbeta. Steric and electrostatic fields were calculated for a training set of 72 compounds using comparative molecular field analysis (CoMFA). The model developed for ERalpha RBA yielded R2 of 0.91 and q(cv)2 of 0.60. The model developed for ERbeta RBA yielded R2 of 0.95 and q(cv)2 of 0.40. Both models were validated successfully using an external test set of 32 compounds. A new concept of test set evaluation based on the variability of the biological response due to the variability of the living organism has been introduced. The CoMFA analysis was supported by a SAR study. In addition to the most favorable steric and electrostatic regions identified by CoMFA, a number of structural descriptors were identified as being important for binding. These are the number of substituents attached to the main skeleton of each compound, the largest distance between the oxygen atoms of each molecule, and the angle defined by the planes that split the phenyl or the naphthyl and the benzisoxazole or the benzoxazole moiety in a morphometrically longitudinal way.
Structure-activity studies have been performed in an attempt to improve the potency of a novel series of azole-based endothelin-A (ET(A)) selective antagonists. Modifications of the hydrophobic group on the terminal urea produced substantial effects on receptor affinity; in particular, the choice of cyclohexyl- or arylureas led to substantial improvements in activity. Conformational restriction of these groups provides an additional benefit. N-Methylation of the indole moiety which is part of the heterocyclic dipeptide surrogate also improves potency. The effects of these two modifications appear to be synergistic, with the best of the resultant doubly modified analogs (e.g. 14q, 15y, and 15ff) exhibiting an 80-200-fold improvement over the original leads.
The oral absorption profile of a family of azole-based ET(A)-selective antagonists has been improved through a rational series of structural modifications which were suggested by analysis of the physicochemical parameter delta log P. Comparison of urea 2 with a series of well-absorbed compounds using delta log P analysis suggested that 2 has an excess capacity for forming hydrogen bonds with solvent. A series of urea modifications were explored as a means of reducing H-bonding capacity while maintaining affinity for the ET(A)-receptor. The correlation between delta log P values and absorption in an intraduodenal (id) bioavailability model was good; this strategy uncovered replacements for each of the urea NH groups which simultaneously improve both potency and drug absorption. A combination of these optimized modifications produces carbamate 16h, a highly-selective ET(A) antagonist with a potency/bioavailability profile consistent with an oral route of administration.
Alternative substrates for DNA and RNA polymerases offer an important set of biochemical tools. Many of the standard methods for nucleoside triphosphate synthesis fail in the cases of nonpurine and nonpyrimidine nucleosides. An efficient preparation of the 5'-O-tosylates for both the deoxy- and ribonucleosides enabled preparation of the diphosphate esters by displacement with tris(tetra-n-butylammonium) pyrophosphate. Enzymatic synthesis of the azole carboxamide deoxyribonucleoside triphosphate was based on ATP as the phosphate donor, nucleoside diphosphate kinase as the catalyst, coupled with phosphoenol pyruvate (PEP) and pyruvate kinase as an ATP regeneration system. Ribonucleoside triphosphate synthesis required PEP as the phosphate donor and pyruvate kinase as the catalyst. An optimized purification procedure based upon boronate affinity gel was developed to yield highly purified nucleoside triphosphates. The strategy outlined here provides a new and efficient method for preparation of nucleoside 5'-triphosphate and is likely applicable to a broad variety of base and sugar modified nucleoside analogues.
The reactivity of 6-haloimidazo[1,2-a]pyridine toward different azoles is reported. The process was shown to be highly dependent on the reaction conditions. Using copper(I) catalyst, the product of ipso substitution was obtained. In the absence of copper, with cesium carbonate in N,N-dimethylformamide, a cine substitution took place.
[Chemical reaction: see text] Various substituted 2-aminotetrahydroazolopyridines and 2-aminohexahydroazolopyridines have been prepared by bromine-mediated addition of protected guanidine or urea to hydropyridine derivatives. The pH-dependent regioselective cleavage of the resulting aminal function led to the 2-aminoazole products III. The yields of the bicycles of type II, and their conversion into azoles III depends on the electronic properties of the substituents on the nitrogen of the tetrahydopyridine.
[reaction: see text] We herein report a new cobalt-catalyzed method for arylation of azole heteroarenes, including thiazole, oxazole, imidazole, benzothiazole, benzoxazole, and benzimidazole. The direct arylation of thiazole and oxazole was achieved both with iodo- and bromoarenes as the aryl donors in the presence of cobalt catalyst [Co(OAc)(2)/IMes] and cesium carbonate, while imidazole required the use of zinc oxide as the base. A complete reversal of arylation from C-5 to C-2 was accomplished using the bimetallic Co/Cu/IMes system. A direct comparison of the new cobalt method and the previously developed palladium protocol revealed significant differences, in terms of both chemical yield and selectivity.
[reaction: see text] 6-(Imidazol-1-yl)-, 6-(benzimidazol-1-yl)-, and 6-(1,2,4-triazol-4-yl)purine nucleosides undergo a nickel-mediated C-C cross-coupling of azole-substituted purine derivatives with arylboronic acids to give good yields of 6-arylpurine nucleosides.
The antifungal activity of nyasol (NYS) alone or with various antifungal agents was measured in vitro against Candida albicans, Aspergillus fumigatus, and Trichophyton mentagrophytes. NYS is a compound recently purified from a medicinal plant, Anemarrhena asphodeloides. Among 12 agents, miconazole (MCZ), ketoconazole (KCZ), clotrimazole (CTZ), and cerulenin showed marked synergistic effects against C. albicans. The fractional inhibition concentration (FIC) indices against 4 strains of C. albicans were 0.067-0.31 for MCZ plus NYS, 0.078-0.31 for KCZ plus NYS, and 0.098-0.13 for CTZ plus NYS. These values indicate the possibility of using NYS as an adjuvant to azole agents in the chemotherapy of candidiasis.
1. The capacity of a number of antifungal azoles, CNS-active drugs (anticonvulsants, antidepressants, antipsychotics and benzodiazepine hypnosedative-anxiolytics) and nonsteroidal anti-inflammatory agents (NSAIDs) to inhibit human liver microsomal 4-nitrophenol (4NP) hydroxylation, a marker of CYP2E1 activity, was investigated. 2. The imidazoles bifonazole, clotrimazole, econazole and miconazole were un- or non-competitive inhibitors of 4NP hydroxylation, with apparent Ki values ranging from 4 to 25 microM. Fluonazole, itraconazole and ketoconazole caused minor or negligible inhibition. 3. Of the CNS-active drugs screened, significant inhibition occurred only with tricyclic antidepressants, phenothiazine antipsychotics and two benzodiazepines (flurazepam and medazepam). Un- or non-competitive inhibition was similarly observed for the tricyclic antidepressants, phenothiazines, flurazepam and medazepam, with apparent Ki values ranging from 175 to 1000 microM. 4. Diclofenac and flufenamic acid were the only NSAIDs found to inhibit 4NP hydroxylation substantially; kinetic analysis was suggestive of activation-inhibition phenomena. 5. These data indicate that, although not substrates for CYP2E1, some clinically used drugs have the capacity to inhibit this enzyme and hence have the potential to modulate the toxicity of non-drug xenobiotics metabolized by CYP2E1.
Low, reproducible minimal inhibitory concentrations against Candida species, with sharp, precise end points in complex media were achieved for imidazoles (clotrimazole, econazole, miconazole, tioconazole and ketoconazole) and triazoles (fluconazole, itraconazole, vibunazole, ICI 153066) by including in the test medium antibacterial antibiotics that bind to the 80S eukaryotic ribosome and inhibit protein synthesis, i.e. blasticidin, cycloheximide, doxycycline, neomycin and gentamicin. The presence of these antibiotics reduced MICs, on average, by 50- to 250-fold. Other protein synthesis inhibitors (rifampicin, erythromycin, lincomycin, clindamycin, chloramphenicol and fusidic acid) were not effective, and the antibiotics did not affect MICs for Aspergillus species. The low azole MICs were in close agreement with MICs obtained in a defined, tissue culture-based medium lacking added antibiotics.
We enrolled 382 college-age women in a cross-sectional survey to investigate the relationship between use of over-the-counter (OTC) azole-based antifungal drugs and vaginal colonization by drug-resistant Candida. This study showed no correlation (P=.506) between previous OTC exposure and colonization of drug-resistant Candida in vaginal flora. However, a small number of resistant Candida species isolates were obtained from women with a history of multiple exposures to OTC antifungals; given the widespread use of these products, this may be an emerging concern.