Mechanism of Action of the Fungicide Thiabendazole, 2-(4′-Thiazolyl) Benzimidazole

Thiabendazole, 2-(4'-thiazolyl) benzimidazole (TBZ) inhibited the growth of Penicillium atrovenetum at 8 to 10 mug/ml. Oxygen consumption with exogenous glucose was inhibited at 20 mug/ml, but endogenous respiration required more than 100 mug/ml. TBZ inhibited completely the following systems of isolated heart or fungus mitochondria: reduced nicotinamide adenine dinucleotide oxidase, succinic oxidase, reduced nicotinamide adenine dinucleotide-cytochrome c reductase, and succinic-cytochrome c reductase at concentrations of 10, 167, 10, and 0.5 mug/ml, respectively. Cytochrome c oxidase was not inhibited. Antimycin A and sodium azide caused the usual inhibition patterns for both fungus and heart terminal electron transport systems. In the presence of antimycin, the fungicide inhibited completely succinate-dichloro-phenolindophenol reductase and succinate-2, 2-di-p-nitrophenyl-(3, 3-dimethoxy-4, 4-biphenylene-5, 5-diphenylditetrazolium)-reductase at 2 and 4 mug of TBZ per ml, respectively. Coenzyme Q reductase required 15 mug/ml. TBZ reduced the uptake by P. atrovenetum of glucose and amino acids and decreased the synthesis of various cell components. At 120 mug/ml, the incorporation of labeled carbon from amino acids-U-(14)C was decreased: lipid, 73%; nucleic acids, 80%; protein, 80%; and a residual fraction, 89%. TBZ did not inhibit peptide synthesis in a cell-free protein-synthesizing system from Rhizoctonia solani. Probably the primary site of inhibition is the terminal electron transport system and other effects are secondary.     

Mechanism of killing of HeLa cells by the antitumor sulfonylurea,N-(4-methylphenylsulfonyl)-N′-(4-chlorophenyl)urea (LY 181984)

Summary The antitumor sulfonylureas appear to inhibit both mitochondrial activity in susceptible human colon lines and to inhibit the oxidation of NADH by isolated plasma membrane vesicles from HeLa cells. The results reported here describe the morphological appearance of HeLa cells treated with the antitumor sulfonylurea N-(4-methylphenylsulfonyl)-N-(4-chlorophenyl)urea (LY181984). The cells remain viable for several days although the rate of increase in cell number is slowed especially at high concentrations of the drug. Cells become smaller with normal nuclei or maintain a normal size but contain multiple or enlarged nuclei. The morphological observations suggest that the drug may somehow interfere with the ability of the cells to enlarge following cytokinesis. Between 72 and 96 h, the cells begin to die. Cell death is accompanied by a condensed and fragmented appearance of the nuclear DNA as revealed by fluorescence microscopy with 4,6-diamidino-2-phenylindole suggestive of apoptosis. Early transients in loss of pH control (4 min after sulfonylurea addition) and an increase in cytoplasmic calcium (4 h after sulfonylurea addition) were observed but were small and perhaps secondary to the mechanism responsible for the failure of the cells to grow and ensuing cell death.     

Synthesis,reactivity and biological activity of N(4)-boronated derivatives of 2′-deoxycytidine

By seeking new stable boron-containing nucleoside derivatives, potential BNCT boron delivery agents, a novel synthetic approach was tested, aimed at a boron attachment via a single bond to an aliphatic carbon of sp³ hybridization. The latter allowed successful modification of deoxycytidine in the reaction with 2-(iodomethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane of the deoxynucleoside amino group. For new compounds, detailed NMR, LDI HRMS (Laser Desorption/Ionization High-Resolution Mass Spectrometry) analyses along with in vivo phosphorylation studies, toxicity assays and DFT modelling are presented.     

Spectral and inhibitory interactions of (±)−3, 4-methylenedioxyamphetamine (MDA) and (±)−3, 4-methylenedioxymethampetamine (MDMA) with rat hepatic microsomes

Incubation of racemic methylenedioxyamphetamine (MDA) or methylenedioxymethamphetamine (MDMA) with rat hepatic microsomes, in the presence of NADPH, generated a spectrally observed inhibitory complex with cytochrome P-450. The complex inhibited product formation from MDA and MDMA as well as other P-450 dependent reactions such as benzphetamine demethylation and CO binding. In the absence of NADPH, MDMA and MDA generated type I and type IIa difference spectra, respectively, suggesting differences in their binding to the enzyme active site. The N-demethylation of MDMA was partially inhibited by methimazole suggesting involvement of the hepatic flavin-containing monooxygenase.     

Synthesis of (±)-4′-Ethynyl and 4′-Cyano Carbocyclic Analogues of Stavudine (d4T)

The synthesis of (±)-4′-ethynyl (8) and 4′-cyano (9) carbocyclic analogues of the anti-HIV agent stavudine (5, d4T) is reported. The carbocyclic unit (16) was constructed from readily available β-keto ester 10. The ethynyl or cyano group of 8 and 9 were prepared, after the introduction of thymine base to 16, by manipulation of the ester function. Evaluation of the anti-HIV activity of 8 and 9 was also carried out.     

Crystal structure of 4-(N-acetyl,2,3,4-tri-O-acetyl-β-l-arabinopyranosylamino)azobenzene

The crystals of the title compound, C₂₅H₂₇N₃O₈ (M_r497.55), are monoclinic, space group P2₁ with a = 11.680(2), b = 8.089(1), c = 13.804(3) Å, β = 92.52(2)°, V = 1302.7 ų, and Z = 2; D_c = 1.27 g.cm⁻³. The structure was solved by using direct methods. The refinement of all non-hydrogen atom parameters yielded R = 0.050. The compound has normal geometry with the ¹C₄ conformation of the pyranoid ring and the extended trans conformation of the azobenzene moiety.     

Production of zearalenone-4-glucoside,a-zearalenol-4-glucoside and ß-zearalenol-4-glucoside

The work at hand describes the production of the zearalenone (ZON) metabolites zearalenone-4-glucoside (ZON-4G), a-zearalenol-4-glucoside (oc-ZOL-4G) and ß-zearalenol-4-glucoside (ß-ZOL-4G). In a first step a genetically modified yeast strain, expressing theArabidopsis thaliana UDP-glu-cosyltransferase UGT73C6, was treated with ZON to produce ZON-4G. The substance was purified by solid phase extraction and subsequent reversed phase preparative HPLC prior to the reduction with sodium borohydride to yield 0C-ZOL-4G and ß-ZOL-4G. The identity and purity of the substances were confirmed by¹³C-and¹H-NMR as well as by HPLC-UV. In total, 50 mg of ZON were used to produce 5 mg of a-ZOL-4G with a purity of 98%, 6 mg of ß-ZOL-4G with a purity of 99% and 5 mg of ZON-4G with a purity of 99%.     

Occurrence of Endogenous Pollen Growth Inhibitors, 4-Hydroxybenzoic Acid and 4-(β-D-Glucopyranosyloxy)benzoic Acid,in the Pollen of Pinus densiflora†

A Pseudomonas strain capable of using pyrazinamide as the sole source of nitrogen was isolated from soil. An aromatic amidase from the bacterium was purified 400-fold to homogeneous on polyacrylamide gel electrophoresis. The enzyme had a molecular weight of 43,000 by gel filtration on Sephadex G-150 and consisted of two identical subunits. The isoelectric point was at 4.45. Among the compounds tested, pyrazinamide (relative activity, 100%), nicotinamide (60%), and 5-methylpyrazinamide (3.4%) were hydrolyzed at considerable rates. Benzamide, picolinamide, and isonicotinamide were not substrates. Apparent Km of the enzyme for pyrazinamide and nicotinamide were 5.6 × 10 ^?5 m and below 5 × 10^?6 m, respectively. The enzyme was not able to hydrolyze aliphatic amides. The enzyme was most active between pH 6.5 and 10 and 75°C, and was stable between pH 5.5 and 8.5 and below 45°C.     

Metabolism of (2Z,4E)-γ-Ionylideneethanol and (2Z,4E)-γ-Ionylideneacetic Acid in Cercospora cruenta

[2–¹⁴C]-(2Z,4E)-γ-Ionylideneethanol and [2–¹⁴C]-(2Z,4E)-γ-ionylideneacetic acid were converted by Cercospora cruenta to [2–¹⁴C]-(2Z,4E)-1′,4′-dihydroxy-γ-ionylideneacetic acid and [2-¹⁴C]-(2Z,4E)-4′-hydroxy-γ-ionylideneacetic acid, which are intermediates of ABA biosynthesis in C. cruenta.     

The biotransformation of α-(2, 4, 6-trimethylphenyl) ethylamine by rabbit liver preparations

Microsomal incubation of the parent amine, α-(2, 4, 6-trimethylphenyl) ethylamine, VI, produced imine, II, alcohol, IV, oxime, V, and several unknowns. The isolation of imine, II, produces evidence that imines may be involved in the microsomal deamination of primary amines. Separate incubations of the imine, II, produced oxime, V, and several unknowns, one of which is tentatively identified as the nitro derivative. Incubation of the oxime, V, gave the alcohol, IV, the “nitro” metabolite as above and 2 unknowns. Incubation of the hydroxylamine, VII, gave oxime, V, alcohol, IV, 2 unknowns and the “nitro” metabolite.     

Microbial transformation of 1,6-dichloro-1,6-dideoxy-β,D-fructofuranosyl-4-chloro-4-deoxy-α,D-galactopyranoside (TGS) by soil populations

Summary Soil microorganisms from one site were shown to be consistently capable of the transformation of 1,6-dichloro-1,6-dideoxy-,d-fructofuranosyl-4-chloro-4-deoxy-,d-galactopyranoside (TGS) in laboratory batch cultures. With fresh soils, all of the available chloride ions were released from the molecule. Subcultures of a TGS-dehalogenating bacterial community produced a progressive decline in the dehalogenating capabilities towards the substrate. The soil organisms did not utilise TGS as a carbon source. The transformation was achieved by co-metabolism and was probably supported by an unknown component in the soil. Four bacterial species were isolated from the TGS-dehalogenating soil community: twoBacillus species, anAcinetobacter group isolate and aMicrococcus group isolate. Thin-layer chromatography confirmed the disappearance of the chlorosugar and high-performance liquid chromatography demonstrated that neither of the constituent monosaccharides—1,6-dichlorofructose nor 4-chlorogalactosucrose was accumulated as an intermediate.

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Resumen Microorganismos de suelo de cierto lugar demostraron consistemente ser capaces de realizar la transformación de 1,6-dicloro-1,6 dideoxi--D-fructofuranosil-4-cloro-4-deoxi-,D-alactopiranosa (TGS) in culturas de laboratorio de tipo discontinuo. Con muestras frescas de suelo, todos los iones cloruro fueron liberados de la molecula. Subculturas de una comunidad bacterial capaz de dehalogenizar TGS produjeron una declinación progresiva de la capacidad de dehalogenizar el substrato. Los microorganismos no utilizaron el TGS como fuente de carbono. La transformación se realiza por co-metabolismo y probablemente se base en un componente del suelo, no determinado. Cuatro especies bacteriales fueron aisladas de la comunidad de bacterias de suelo con capacidad de dehalogenar el TGS: dos especies deBacilo, unaAcinelobacteria y unMicrococo. Estudios de cromatografía de capa delgada confirmaron la desaparición del clorosacárido, y estadios de cromatografía liquida demostraron que ninguno de los componentes monoscáridos — 1,6-diclorofructuosa y 4-clorogalactosucrosa — eran acumulados como productors intermedios.

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Résumé Les microorganismes du sol d'un certain endroit ont été démontrés être capable, sans exception, de la transformation de 1,6-dichloro-1,6-dideoxy-,D-fructofuranosyl-4-chloro-4-deoxy-,D-galactopyranoside (TGS) en cultures de laboratoire du type discontinu. Avec des prélèvements frais du sol, tous les ions disponibles de chlorure ont été libérés de la molécule. Des souscultures d'une communauté bactérienne capable de déhalogeniser le TGS ont produit un déclin progressif de la capacité de déhalogeniser le substrat. Les microorganismes du sol n'ont pas utilisé le TGS comme source de carbone. La transformation s'est accomplie par cometabolisme et, probablement, s'est basée sur un component indéterminé du sol. Quatre espèces bactériennes ont été isolées de la communauté de bactéries du sol capable de déhalogeniser le TGS: deux espèces deBacillus, unAcinetobacter et unMicrococcus. Des études de chromatographie de couches fines ont confirmées la disparition du chlorosaccharide, tandis que des études de chromatographie liquide de haut rendement ont démontrées que, des monosaccharides constituants, ni 1,6-dichlorofructose ni 4-chlorogalactosucrose, n'ont été accumulés comme produits intermédiaires.

     

Fragmentation of realgar,As4S4, controlled by transition metalligand systems

The chemical behavior of the realgar molecule, As₄S₄, toward various (triphos)M moieties has been investigated. The reaction of As₄S₄ with [{MCl(cod)}₂] (M=Rh or Ir; cod=1,5-cyclooctadiene) in the presence of the ligand triphos [triphos=1,1,1- tris(diphenylphosphinomethyl)ethane] yields compounds of formula [(triphos)M(η³-As₃S₃)]·C₆H₆ containing the new As₃S₃ unit, which is trihapto bonded to the metal atom through one sulfur and two arsenic atoms. Such a As₃S₃ fragment is the largest one so far extruded from the realgar molecule. The As₄S₄ molecule undergoes more drastic disruptions in the reactions with Co(BF₄)₂·6H₂O and Ni(BF₄)₂·6H₂O in the presence of triphos. These results suggest that the fragmentation of the As₄S₄ molecule is controlled by the nature of the metal atom involved in the reaction.     

Studies on Glycosides of 3, 4, 6-Trisubstituted Pyrazolo-[3, 4-D]Pyrimidines. Synthesis of 2′-Deoxyribonucleosides

Abstract

A synthesis of 4,6-dimethylthio-1-(2-deoxy-β-D-erythro-pentofuranosyl)pyrazolo[3,4-d]pyrimidine-3-carbonitrile (4) is described using the stereospecific sodium salt glycosylation procedure. Condensation of the sodium salt of 4,6-dimethylthiopyrazolo[3,4-d]pyrimidine-3-carbonitrile (1) with 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-α-D-eythro-pentofuranose (2) gave exclusively the corresponding blocked nucleoside (3) with β-anomeric configuration, which on deprotection provided 2′-deoxyriboside 4. Aglycone functional groups transformations of 4 led to related 3,4,6-trisubstituted pyrazolo[3,4-d]pyrimidine-2′-deoxynucleosides. These compounds are devoid of any significant cytotoxic activity in vitro.     

Synthesis of 1-(4-Keto-2, 3-O-isopropylidene-α-L-rhamnopyranosyl) uracil

Abstract

Synthesis of 1-(2, 3, 4-tri-0-acetyl-α-L-rhamnopyranosyl) uracil (3), 1-(α-L-rhamnopyranosyl) uracil (4), 1-(2, 3-0-isopropylidene-α-L-rhamnosyl) uracil (5), and 1-(2, 3-0-isopropylidene-4-keto-α-L-rhamnopyranosyl) uracil (6) are reported. Oxidation of (5) to (6) was effected using pyridinium chlorochromate in presence of molecular sieves.