Fluorometrische Bestimmung von Aminen und Aminos?uren mittels 5-Isothiocyanato-1,3-dioxo-2-p-tolyl-2,3-dihydro-1H-benz[de]isochinolin

Ohne Zusammenfassung

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Fluorometric determination of amines and amino acids with 5-Isothiocyanato-1,3-dioxo-2-p-tolyl-2,3-dihydro-1H-benz[de]isoquinoline

     

Synthesis of some new bicyclic pyrazoline derivatives

2,6-Diarylidenecyclohexanones react with hydrazine to give the corresponding bicyclic pyrazolines. The synthesis of a series of twenty eight substituted pyrazolines is described. The structure of all products was confirmed by microanalyses, ir and nmr data.     

An efficient and highly stereocontrolled route to bulgecinine hydrochloride

(-)-Bulgecinine is a nonproteinogenic amino acid component present in bulgecins A, B, and C, antibiotic glycopeptides derived from Pseudomonas acidophila and Pseudomonas mesoacidophila. In combination with beta-lactam antibiotics, bulgecins exihibit a unique synergistic antibacterial activity against various Gram-negative microorganisms. Utilizing d-serine as a chiral template and employing a highly regio- and stereoselective intramolecular amidomercuration-oxidation protocol in the key pyrrolidine ring forming step, an efficient total synthetic route to enantiopure bulgecinine is reported herein.     

Stereoselective route to the ezoaminuroic acid core of the ezomycins

Starting from readily available (R)-glycidol, an efficient pathway to a strategically functionalized ezoaminuroic acid derivative of the antifungal ezomycins has been developed. A key transformation in the synthesis involves regio- and stereoselective conversion of the olefinic functionality of a 5,6-dihydropyran-2-one to the C-2, C-3 trans-1,2-amino alcohol moiety as present in ezoaminuroic acid.     

Spectrophotometric determination of ethiofencarb in waters by reaction with p-aminophenol

Summary An automatized procedure has been developed for the spectrophotometric determination of ethiofencarb in water by reaction with p-aminophenol after alkaline hydrolysis to obtain the corresponding phenol sulphone. The hydrolyzed samples are continuously introduced into different manifolds at the same time as 300 mg/l p-aminophenol, 0.004 mol/l KIO₄ and 0.04 mol/l NaOH solutions. The absorbance is measured at 638 nm after a reaction time of 6 min in stop flow. This absorbance band corresponds to the indo dye obtained from the reaction between the phenol sulphone of ethiofencarb and the quinoneimine form of the p-aminophenol and it permits a matrix-free spectrophotometric determination of ethiofencarb with a limit of detection of 33 g/l. The recovery of ethiofencarb in different water matrices varies from 71 to 126%.     

Synthesis and antimicrobial activity of some netropsin analogues

Nine novel lexitropsins were synthesized by linking two netropsin-like moieties through three different dicarboxylic acids; 9,10-dihydro-2,7-phenanthrenedicarboxylic acid; [(3-[[(carboxymethyl)amino]carbonyl]benzoyl)amino]acetic acid and indole-2,5-dicarboxylic acid. The netropsin residues were modified by the use of N-isopentylpyrrole, 5-methylthiophene or 5-isopropylthiazole heterocyclic building blocks in place of the usual N-methylpyrrole. The compounds were tested against five gram-positive bacteria: Staphylococcus aureus, Streptomyces faecalis, methicillin resistant Staphylococcus aureus, Enterobacter cloacae, Mycobacterium fortuitum, three gram-negative bacteria: Klebsiella aerogenes, Proteus vulgaris, Escherichia coli and three fungi: Aspergillus niger, Candida albicans and Aspergillus nidulans. Some of the compounds showed significant inhibitory effects on the growth of the microorganisms.     

Short lexitropsin that recognizes the DNA minor groove at 5'-ACTAGT-3': understanding the role of isopropyl-thiazole

Isopropyl-thiazole ((iPr)Th) represents a new addition to the building blocks of nucleic acid minor groove-binding molecules. The DNA decamer duplex d(CGACTAGTCG)(2) is bound by a short lexitropsin of sequence formyl-PyPy(iPr)Th-Dp (where Py represents N-methyl pyrrole, (iPr)Th represents thiazole with an isopropyl group attached, and Dp represents dimethylaminopropyl). NMR data indicate ligand binding in the minor groove of DNA to the sequence 5'-ACT(5)AG(7)T-3' at a 2:1 ratio of ligand to DNA duplex. Ligand binding, assisted by the enhanced hydrophobicity of the (iPr)Th group, occurs in a head-to-tail fashion, the formyl headgroups being located toward the 5'-ends of the DNA sequence. Sequence reading is augmented through hydrogen bond formation between the exocyclic amine protons of G(7) and the (iPr)Th nitrogen, which lies on the minor groove floor. The B(I)/B(II) DNA backbone equilibrium is altered at the T(5) 3'-phosphate position to accommodate a B(II) configuration. The ligands bind in a staggered mode with respect to one another creating a six base pair DNA reading frame. The introduction of a new DNA sequence-reading element into the recognition jigsaw, combined with an extended reading frame for a small lexitropsin with enhanced hydrophobicity, holds great promise in the development of new, potentially commercially viable drug lead candidates for gene targeting.     

Phosphated Alumina Catalysts: Surface Properties and Reactivity towards 2-PrOH Decomposition

Summary. The influence of the type of precursor, the phosphate content, as well as the source of phosphate ions on the surface texture, acidity, and catalytic activity of phosphated aluminas has been described. Phosphated alumina catalysts were prepared by impregnating two different precursors with two different sources of phosphate in different loading levels w = 3, 6, and 10% PO₄ ³⁻. The characterisation of the catalyst was performed using X-ray powder diffraction (XRD), thermal analysis (TG), and nitrogen adsorption–desorption methods at 77 K. The surface acidity of the catalysts has been studied by FT-IR spectroscopy of adsorbed pyridine at different temperatures. Moreover, the activity in the catalytic decomposition of isopropanol (2-PrOH) has been investigated at 520 K. Investigation of the surface properties shows that the addition of phosphate ions does not change the crystal phase (γ-phase) and the samples prepared from gel and phosphoric acid have the highest surface area. An FT-IR study of pyridine adsorption shows both Lewis and Br?nsted acid sites on the surface of the samples prepared from gel, while only Lewis acid sites are detected on the samples prepared from crystalline oxide. The catalytic activity by 2-PrOH conversion shows that the conversion of 2-PrOH as well as the selectivity towards propene formation increases from w = 3 to 6% followed by a decline for w = 10%. Moreover, the strongest activity was detected in case of phosphated alumina gel with w = 6% which gives 97.3% propene and 96.1% conversion of 2-PrOH.     

Compounds from the Medicines for Malaria Venture Box Inhibit In Vitro Growth of Babesia divergens,a Blood-Borne Parasite of Veterinary and Zoonotic Importance

Babesiosis is an infectious disease with an empty drug pipeline. A search inside chemical libraries for novel potent antibabesial candidates may help fill such an empty drug pipeline. A total of 400 compounds (200 drug-like and 200 probe-like) from the Malaria Box were evaluated in the current study against the in vitro growth of Babesia divergens (B. divergens), a parasite of veterinary and zoonotic importance. Novel and more effective anti-B. divergens drugs than the traditionally used ones were identified. Seven compounds (four drug-like and three probe-like) revealed a highly inhibitory effect against the in vitro growth of B. divergens, with IC₅₀s ≤ 10 nanomolar. Among these hits, MMV006913 exhibited an IC₅₀ value of 1 nM IC₅₀ and the highest selectivity index of 32,000. The atom pair fingerprint (APfp) analysis revealed that MMV006913 and MMV019124 showed maximum structural similarity (MSS) with atovaquone and diminazene aceturate (DA), and with DA and imidocarb dipropionate (ID), respectively. MMV665807 and MMV665850 showed MMS with each other and with ID. Of note, a high concentration (0.75 IC₅₀) of MMV006913 caused additive inhibition of B. divergens growth when combined with DA at 0.75 or 0.50 IC₅₀. The Medicines for Malaria Venture box is a treasure trove of anti-B. divergens candidates according to the obtained results.     

Synchronization in a multiplex network of gene oscillators

Study of the synchronization in the network of gene oscillator network has vital importance in understanding of rhythmicity of molecular and cellular activities. In this paper, we analyze a network of linearly coupled genetic oscillators in a multiplex structure. The coupling strength values are changed and the coupling range is considered to be fixed, but different in the two layers. The analyses are done in two cases of periodic and chaotic oscillations. By computing the statistical measures, the interlayer and intralayer synchronization states are studied. The results show that the layer with higher coupling range has more enhanced synchrony and is less affected by the turbulent behavior of the other layer. On the other hand, the layer with lower coupling range approaches synchronization by strengthening the interlayer and intralayer couplings. The interlayer synchronization is also achieved in high coupling strength values.