Search results for "stereo"
showing 10 items of 6147 documents
Darstellung und H2-agonistische Aktivität alkylsubstituierter 3-(Imidazol-4-yl)propylguanidine Synthesis and H2-Agonistic Activity of Alkyl-3-(imidaz…
1987
Derivate des 3-(Imidazol-4-yl)propylguanidins mit einem Methyl- oder einem 2-(Ethylthio)ethyl-Substituenten2) an der Guanidin-Gruppe weisen am H2-Rezeptor des Meerschweinchenvorhofs nur 10–20% der Histaminaktivitat auf. Dagegen fuhrt die Substitution mit der H2-affinen 2-[(5-Methylimidazol-4-yl) methylthio]ethyl-Gruppierung zu Impromidin, einem hochpotenten H2-Agonisten.
Racemische Histamin-H1-Agonisten
1984
Es wurden racemische α- und β-methylverzweigte 2-(2-Aminoethyl)-thiazole und 2-(2-Aminoethyl)-imidazole (Isohistamine) dargestellt und auf Histamin-H1- und -H2-agonistische Aktivitat gepruft. Histamine Analogues, XXVI: Racemic Histamine H1-Agonists Racemic α or β-methylated 2-(2-aminoethyl)thiazoles and 2-(2-aminoethyl)imidazoles (isohistamines) were prepared and tested for histamine H1- and H2-agonistic activity.
Histaminanaloge, 27. Mitt. Bis (2,2′-histamine)
1985
Es wurden p-Phenylen-bis(2,2′-histamin) (6a), Ethylen-bis(2,2′-histamin) (6b), Tetramethylen-bis(2,2′-histamin) (6c) und Hexamethylen-bis(2,2′-histamin) (6d) dargestellt und auf Histamin-H1-und H2-agonistische Aktivitat untersucht. Histamine Analogues, XXVII: Bis(2,2′-histamines) p-Phenylenebis(2,2′-histamine) (6a), ethylenebis(2,2′-histamine) (6b), tetramethylenebis(2,2′-histamine) (6c), and hexamethylenebis(2,2′-histamine) (6d) were prepared and tested for histamine H1,-and H2-agonistic activity.
Enantioselective transformation of fluoxetine in water and its ecotoxicological relevance
2017
European legislation focusing on water quality is expected to broaden to encompass several pharmaceuticals as priority hazardous substances. This manuscript aims to challenge current regulatory approaches that do not recognize stereochemistry of chiral pharmaceuticals by testing the hypothesis that environmental transformation and effects of chiral pharmaceuticals are stereoselective. Our experiments revealed that, while degradation of chiral fluoxetine (FL) in river water occurs via non-enantioselective photochemical and mildly-enantioselective microbial processes favoring the (R)-enantiomer, a pronounced enantioselectivity favoring (S)-FL (leading to the formation of (S)-NFL (norfluoxetin…
ChemInform Abstract: Structure and Synthesis of a New Indole Alkaloid, 19(S)-Hydroxy-Nb- methylraumacline, Obtained by the Biotransformation of Ajmal…
2010
The first sorbicillinoid alkaloids, the antileukemic sorbicillactones A and B, from a sponge-derived Penicillium chrysogenum strain
2005
The saltwater culture of a Penicillium chrysogenum strain isolated from the Mediterranean sponge Ircinia fasciculata yielded three new sorbicillin-derived compounds (1-3), whose structures were elucidated mainly by 2D NMR and mass spectrometry. Among them, sorbicillactones A (1) and B (2) are the first sorbicillinoid natural products that contain nitrogen. Compound 1 is anti-HIV active and it exhibits a strong cytotoxic activity against L5178y leukemic cells, combined with a relatively low toxicity to cervical carcinoma HeLa S3 cells and pheochromocytoma PC 12 cells. The absolute configurations of I and 2 were elucidated by quantum chemical calculation of circular dichroism (CD) spectra. An…
Conformational studies into N-methylation of alanine diamide models: A quantitative approach
2006
Abstract A systematic theoretical analysis was performed on N -acetyl- l -alanine N ′-methylamide (Ac- l -Ala-NHMe) and the analogues methylated on the N-terminus (Ac- l -(Me)Ala-NHMe), C-terminus (Ac- l -Ala-NMe 2 ), and both N/C-termini (Ac- l -(Me)Ala-NMe 2 ), to evaluate the influence of methylation of the amide group on the conformational properties of the affected residues. The ϕ , ψ potential energy surfaces were calculated at the B3LYP/6-31+G**//HF/3-21G level of theory with inclusion of the solvent (water) effect (SCRF method). The conformers localised were fully optimised at the B3LYP/6-31+G** in vacuo. The accessible areas of the potential energy surfaces; the number of conformer…
Sometimes less is more—the impact of the number of His residues on the stability of Zn(ii)–SmtB and BigR4 α-5 domain complexes
2021
The increasing number of antibiotic-resistant pathogens has become one of the major health problems of modern times, including infections caused by Mycobacterium tuberculosis. One of the possible mammalian immune system responses to mycobacterial infection is the increase of the zinc(II) concentration in phagosomes to a toxic level. The mycobacterial SmtB protein belongs to the family of ArsR/SmtB transcription regulators. In the presence of high concentrations of metals, SmtB dissociates from DNA and activates the expression of metal efflux proteins. In this work, we focus on the α5 zinc(II) binding domains of SmtB/BigR4 proteins (the latter being the SmtB homolog from non-pathogenic M. sm…
Stereocontrolled synthesis of D-α-hydroxy carboxylic acid from L-amino acids
1987
Abstract Optically active D-α-hydroxy carboxylic acids are obtained from L-amino acids via L-α-halocarboxylic acids and their stereoselective reaction with cesium p-nitrobenzoate.