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  • Open access
  • 44 Reads
Synthesis and antialgal effect of 2-substituted 5,6-dihydro-4,7-dithiaindane-1,3-diones
Derivatives of indane-1,3-diones are compounds showing interesting properties not only from theoretical view. Some 2-arylindane-1,3-diones are used as anticoagulants, dyes, polymerization modifiers and rodenticides. This study deals with synthesis, spectral and antialgal properties of new substituted 2-(5-aryl-2-thenylidene- or 2- furfurylidene)-5,6-dihydro-4,7-dithiaindane-1,3-diones II.
  • Open access
  • 73 Reads
Facile and Efficient Synthesis of Functionalized Asymmetric Porphyrins with Organolithium Reagents
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Functionalized asymmetric porphyrins bearing highly reactive centers in substituents at the mesopositions were synthesized in good yields by the reaction of 5,15-diphenylporphyrin with organolithium reagents. Using these porphyrins as precursors highly complex tetrapyrrolic systems are accessible. The synthetic strategy is based on our earlier reports on the combined use of organolithium and alkyliodide reagents for the functionalization of porphyrins.
  • Open access
  • 40 Reads
Sequence-selective Binding of Small Peptides by Two-armed Receptors
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The increasing need for therapeutics and sensors drives the development of artificial receptors that recognize small peptides selectively. However, the many degrees of freedom of a simple di- or tripeptide make the rational design of a specific receptor for a given peptide to an extremely difficult task. As a result, while nature has evolved enzymes as well as small molecules (e.g. vancomycin) that bind peptides with high affinity and selectivity, so far only a few receptors have been designed rationally [1]. Thus, a more empirical approach that mimics the natural principles of random mutation and selection of the fittest is needed for the successful development of receptors binding small peptides selectively
  • Open access
  • 35 Reads
Synthesis of C-Glycosylated Amino Acids Suitable Building Blocks for the Synthesis of Glycopeptide Mimic
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Glycopeptides are considered as a class of natural products which are responsible for a great variety of molecular recognition processes on the cellular surface including fertilization, pathogen-cell adhesion and the inflammatory response., It appears that the interactions of glycopeptides with their respective ligands is in general mediated by their carbohydrate epitopes. These glycosidic moieties exhibit a great diversity and very complex structures which makes their synthesis an almost arduous task.
  • Open access
  • 48 Reads
DNA-Binding and DNA-Photodamaging Properties of Indolo[2,3-b]-Quinolizinium Bromide
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Cationic dyes have been shown to bind efficiently to DNA [1] and lead to photoinduced DNA damage [2]. Such photobiological features may be used to detect or characterize the nucleic acid [3]. Furthermore the intentional photoinduced damage of DNA, e. g. in tumor cells, may be applied in phototherapy [4,5]. Among the cationic aromatic compounds that have been investigated along these lines are coralyne (1) [6] and related quinolizinium salts [7]. During our studies on photobiological properties of aromatic heterocycles we showed that readily available benzo[b]-quinolizinium salts (acridizinium salts) 2 exhibit pronounced DNA-binding and DNA-photodamaging properties [8]. To further investigate the photobiological features of quinolizinium derivatives we synthesized indolo[2,3-b]- quinolizinium salt (3a) [9]. The interactions of this aromatic dye with DNA seemed to be of special interest since it resembles closely the structure of the known anti-tumor compound Céliptium® 4. Herein, we present preliminary investigations of the interactions of quinolizinium dye 3a with DNA.
  • Open access
  • 45 Reads
Synthesis and Structural Properties of Neoglycolipids Anchored at Membrane Surfaces
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Glycolipids cover the surface of living cells and determine their properties in cell-adhesion processes. The extremely complex and heterogeneous native cell membrane forbids the functional characterization of individual glycolipid components. Homogeneous neoglycolipids on model membranes reduce the complex native glycocalix to its essential features.
  • Open access
  • 54 Reads
Synthesis and Biological Activity of 2-Amino-N-phenylbenzamides and 3-Phenyl-1,2,3-benzotriazin-4(3H)-ones
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A series of substituted 2-amino-N-phenylbenzamides (1) and 3-phenyl-1,2,3-benzotriazin-4(3H)-ones (2) was synthesized and evaluated in vitro for their antimycobacterial, antifungal, and photosynthesis-inhibiting properties. Some compounds 1 exhibited good activity against Mycobacterium tuberculosis as well as against atypical strains of mycobacteria. The introduction of chloro substituent into position 5 improved the antimycobacterial activity of 1. Most 5-chloro derivatives 1 were more active against atypical strains than INH. The most active derivative was 2-amino-5-chloro-N-(4-sec-butylphenyl)benzamide. A moderate antifungal activity against Trichophyton mentagrophytes was found for some 1, but significant activity against the other tested fungal strains was not observed. In general, the ring closure in 3-phenyl-1,2,3-benzotriazin-4(3H)-ones (2) led to decrease or loss of antimycobacterial as well as antifungal activity. The photosynthesis-inhibiting activity of 2 concerning inhibition of oxygen evolution rate in spinach chloroplasts was investigated. The relatively low photosynthesis-inhibiting activity of 2 is probably a consequence of their low aqueous solubility causing a restricted passage of the inhibitor through the hydrophilic regions of thylakoid membranes.
  • Open access
  • 29 Reads
Relative Reactivities of Activated Carboxylic Acids in Amide-Forming Reactions Employed for the Synthesis of Tetraphenylporphyrin Libraries
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Combinatorial synthesis has established itself as a tool for the preparation of libraries of structurally related compounds in an efficient manner.1 The most efficient way of synthesizing a combinatorial library would, of course, involve a single reaction, in which a mixture of all required building blocks reacts to produce the desired products. This approach has proven impractical for several reasons. One is the challenges associated with performing a work-up and purification of the product mixture produced in a massively combinatorial one-pot synthesis. Another, perhaps more fundamental reason is the unequal reactivities of building blocks, which leads to non-statistically distributed product mixtures, unless the stability of the products is identical (reaction performed under thermodynamic control) or the reactivities of the building blocks employed are equal (reaction performed under kinetic control). As a result, most combinatorial syntheses are performed on solid supports2,3 and in a format in which no more than one building block reacts with its substrate(s) in any given reaction mixture. This research note reports on a modest exercise in the realm of competitive, mixed condensation reactions leading to combinatorial libraries in a one-pot procedure.
  • Open access
  • 19 Reads
Aplyzanzine A, A new Dibromotyrosine derivative from a Verongida sponge
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Aplyzanzine A (1), a novel bisdibromotyrosine derivative has been isolated from the Indo-Pacific sponge Aplysina sp. Its structure was elucidated mainly on the basis of 1D and 2D-NMR and MS spectroscopic data. A biomimetic synthesis, which might well be the biosynthesis of 1, is suggested.
  • Open access
  • 51 Reads
Ultrasound Promoted Synthesis of 2,3-bis-(4-Hydroxyphenyl)-indoles as Inherently Fluorescent Ligands for the Estrogen
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A series of 2,3-bis-(4-hydroxyphenyl)-indoles (4c-f) was prepared by ultrasound promoted intramolecular cyclodehydration of a -anilinyl (or m-anisidyl)-desoxyanisoins (2c-f) and their optical spectroscopy and receptor binding properties have been investigated. These compounds showed intense long wavelength fluorescent emission which is sensitive to solvent polarity and pH. However, their binding affinities to ER is modest, except of 2,3-bis-(4-hydroxy-phenyl)-1-methyl-1H-indol-6-ol (4e) which has reasonably good affinity and may be used for further development.
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