Synthesis of 0-(2-0-α-D-glucopyranosyl)-β-D-galactopyranoside of optically pure δ-hydroxyl-L-lysyl-glycine: a glycopeptide of the glomerular basement membrane

The synthesis of the glycopeptide Glu-Gal-Hyl-Gly, which forms an essential part of the Glomerlar Basement Membrane, is presented. The use of the levulinyl group as a protective group and the availability of the optically pure and fully-protected lactone of δ-hydroxy-L-Lysine (Hyl) will be put forward.     

Synthesis of an S-linked glycopeptide analog derived from human Tamm-Horsfall glycoprotein

Direct base catalyzed S-glycosylation of a cysteine and a homocysteine containing peptide with O-acetyl protected bromides in DMF-water solution furnished two glycopeptide fragments. The two glycopeptide fragments were linked to the target glycopeptide with two S-glycosyl residues mimicking a part of Tamm-Horsfall glycoprotein.     

Probing the influence of cis-trans isomers on model lipid membrane fluidity using cis-parinaric acid and a stop-flow technique

Stop-flow experiments exploiting the fluorescence of cis-parinaric acid in monounsaturated lipid vesicles allow the model membrane behaviour, notably the membrane fluidity, to be correlated to the cis:trans lipid ratios.     

The glomerular basement membrane as a model system to study the bioactivity of heparan sulfate glycosaminoglycans

The glomerular basement membrane and its associated cells are critical elements in the renal ultrafiltration process. Traditionally the anionic charge associated with several carbohydrate moieties in the glomerular basement membrane are thought to form a charge selective barrier that restricts the transmembrane flux of anionic proteins across the glomerular basement membrane into the urinary space. The charge selective function, along with the size selective component of the basement membrane, serves to limit the efflux of plasma proteins from the capillary lumen. Heparan sulfate glycosaminoglycans are anionically charged carbohydrate structures attached to proteoglycan core proteins and have a role in establishing the charge selective function of the glomerular basement membrane. Although there are a large number of studies in the literature that support this concept, the results of several recent studies using molecular genetic approaches to minimize the anionic charge of the glomerular basement membrane would suggest that the role of heparan sulfate glycosaminoglycans in the glomerular capillary wall are still not yet entirely resolved, suggesting that this research area still requires new and novel exploration.     

Quinazolines X. Synthesis of 6,6'-methylenebisdeoxyvasicinone and its homologs

Summary 6,6-Methylenebisdeoxyvacisinone and its homologs have been synthesized by the reaction of methylenebisanthranilic acid with lactams (-butyrolactam, -valerolactam, -caprolactam, and -chloro- and ,-dichloro--caprolactams). The condensation of anthranilic acid and its derivatives (4-nitro-, 5-bromo-, 5-iodo-, and 5-nitroanthranilic acids) with ,-dichloro--caprolactam has given seven-membered analogs of deoxyvasicinone containing two chlorine atoms in the polymethylene ring.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 544–547, July–August, 1977.     

Polymeric Schiff Bases. X. The Synthesis and Evaluation of Polymeric Azomethines from Aminoarylcarbonyl Monomers

Abstract

The syntheses of polymeric azomethines from aminoarylcarbonyl monomers, H₂NArCOR, are described and the thermal stabilities of the polymers found to be comparable to polymers prepared by the reaction of aryldicarbonyl compounds with aryldiamines.     

Synthesis and characterization of an ultrathin polyion complex membrane containing β-cyclodextrin for separation of organic isomers

An ultrathin polyion complex (PIC) layer containing β-cyclodextrin (β-CD) was formed on the surface of a charged base membrane. Thus, a positively charged copolymer containing β-CD was synthesized by the radical copolymerization of β-CD monomer and allylamine, and was used to modify the surface of a Nafion membrane containing negatively charged fixed ions. Electron spectroscopy for chemical analysis (ESCA) confirmed the presence of the copolymer on the surface of the Nafion membrane due to the formation of a PIC layer. The ability of the membrane to separate organic isomer mixtures was tested by the pervaporation technique, using butanol isomer mixtures as the feed model. The membrane exhibited a good selectivity toward butanol isomers, indicating the effectiveness of β-CD as a selective fixed carrier for the isomers.     

Synthesis of 0-(2-0-α-d-glucopyranosyl)-β-d-galactopyranoside of optically pure δ-hydroxy-l-lysylglycine and -gd-hydroxy-l-lysylglycyl-l-glutamyl-l- aspartylglycine: Components of the glomerular basement membrane

The application of the levulinyl group as a temporary blocking group for the 2-OH function of galactose proved to be very efficient not only for the introduction of a β-linkage between galactose and the optically pure δ-hydroxy-l-lysylglycine, but also to link galactose, via an α-interglycosidic bond, with glucose. The partially protected glycodipeptide (7b) served as the starting product for the preparation of the naturally occuring glycopentapeptide (9b). The preparation of a conjugate between bovine serum albumin and the glycodipeptide (7c) will also be reported.     

Synthesis and characterization of an amphoteric ion-exchange membrane

An amphoteric ion-exchange membrane was prepared by chemical grafting of acrylic acid and dimethyl amino-2-ethyl methacrylate on ozonized polyethylene. The effects of the variation of external pH on the physicochemical properties of this membrane were studied (exchange capacity, electrical resistance, water and electrolyte content, and membrane potential). The determination of the mean activity coefficient of the NaCl in the membrane phase using the Donnan equilibrium equation reveals that this coefficient increases with the NaCl concentration in the external solution. Fundamental electrochemical properties of the amphoteric membrane are discussed on the basis of the variation of the membrane selectivity with the external electrolyte concentrations and the pH. The properties at neutral pH are accounted for by a mutual neutralization of some acidic and basic groups in the membrane phase.     

Synthesis,characterization, and antimicrobial studies of some palladium complexes with an octamethyl tetraazacyclotetradecadiene ligand and isomers of its reduced form

Biologically important tetraaza-macrocyclic ligand 3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene dihydroperchlorate, Me₈[14]diene·2HClO₄ (L₁·2HClO₄) was synthesized by the condensation of 1,2-diaminopropane with acetone in presence of quantitative amount of HClO₄ and three isomeric ligands designated as L_A, L_B and L_C were separated by the reduction of L₁·2HClO₄ with NaBH₄ and fractional crystallization from xylene. The nitrato, nitro, bromido, and iodido complexes of palladium with diene ligand L₁ were prepared by the interaction of L₁·2HClO₄ with K₂[Pd(NO₃)₄], K₂[Pd(NO₂)₄], K₂[PdBr₄], and K₂[PdI₄] (prepared by the reactions with PdCl₂ with KNO₃, KNO₂, KBr, and KI, respectively), respectively. The bromide and iodido complexes of L_A were prepared by the axial substitution reactions with [PdL_ACl₂]Cl₂. By contrast, similar complexes of other isomeric ligands L_B and L_C were prepared by axial addition reactions of [PdL^?][PdCl₄] (L′?=?L_B or L_C) with KBr and KI, respectively. The complexes were characterized on the basis of elemental analysis: IR, ¹H-NMR, UV–Vis spectroscopic analysis, and magnetic and molar conductivity data. The antifungal and antibacterial activities of these compounds have been studied against some phyto-pathogenic fungi and bacteria.     

Synthesis of macrocycle isomers via metathesis cyclization and their self-assembly from aqueous solutions

Novel triangular macrocycle isomers were synthesized through metathesis cyclization with high yield (77%). HPLC and MALDI-TOF showed that the purity of the macrocycles was higher than 99%, while (1)H NMR clearly showed that these macrocycles contain C2 and C3 isomers in a ratio of 1:3. AFM and TEM showed that they spontaneously formed vesicular structures in a chloroform/water system with an average diameter of 460 nm, which was corroborated by DLS results.     

The identification of 3,4-MDMA from its mass equivalent isomers and isobaric substances using fast LC-ESI-MS-MS

3,4-methylenedioxymethamphetamine (3,4-MDMA, "Ecstacy") and its 17 isomers and isobaric substances are studied using liquid chromatography (LC)-positive electrospray ionization-mass spectrometry (MS). 3,4-MDMA is a controlled substance, whereas in many countries the other studied isobaric compounds are not. A method for confirmation of the presence of 3,4-MDMA in drug seizures is developed and validated. Using single MS, the compounds produce an intense protonated molecule and some characteristic fragments; but tandem MS (MS-MS) is applied to enhance specificity. The MS-MS fragmentation is studied in order to distinguish 3,4-MDMA from the other 17 related compounds. However, the MS-MS spectra of 3,4-MDMA and six related compounds are very similar. Therefore, the LC-MS-MS method is developed for the unambiguous identification of 3,4-MDMA. The use of a monolithic column allows for 5-min gradient runs. This qualitative method is tested with 49 Ecstacy samples seized by the police. All results are congruent with the ones obtained with other methods.     

Synthesis of caulersin and its isomers by reaction of indole-2,3-dicarboxylic anhydrides with methyl indoleacetates

1-Benzenesulfonylindole-2,3-dicarboxylic anhydride was reacted with methyl 1-benzenesulfonylindole-2-acetate to give the corresponding 2-acylindole-3-carboxylic acid as the sole product in high yield, which could be converted to caulersin in four steps. In a similar manner, three isomers A, B, and C were synthesized by reaction of indole-2,3-dicarboxylic anhydrides with methyl indoleacetates.     

Synthesis of a C-glycoside analogue of beta-D-galactosyl hydroxylysine and incorporation in a glycopeptide from type II collagen

A stereoselective synthesis of the C-glycoside analogue of beta-D-galactosyl-(5R,2S)-hydroxylysine (1) has been achieved starting from tetra-O-benzyl-D-galactopyranosyl lactone. The synthesis involved establishment of three stereogenic centers in an unambiguous manner. A facially selective Grignard reaction followed by a silane reduction was used for the anomeric position of the C-galactose residue. An Evans allylation established the configuration of the delta-aminomethylene group of the hydroxylysine moiety, whereas an asymmetric hydrogenation utilizing Burk's catalyst was used for the alpha-amino acid moiety itself. The synthesis was completed in 17 steps with an overall yield of 18%, resulting in the most complex and functionalized C-glycoside analogue of a naturally occurring glycosylated amino acid prepared to date. In addition, amino acid 1 was incorporated in a glycopeptide from type II collagen known to be crucial for the response of autoimmune T cells obtained in models of rheumatoid arthritis. A preliminary immunological study revealed that four out of five members in a panel of T cell hybridomas were able to recognize this C-linked glycopeptide when presented by A(q) class II MHC molecules.     

Synthesis and some transformations of sulfides of the thiophene series. X. Preparation of thienoisothiazoles from mercaptoaldimines

The action of bromine on 2-mercapto-5-alkyl-3-thienylidenimines gives thieno[3, 2-d]isothiazole bromides. 5-Ethylthieno[3, 2-d]isothiazole bromide readily splits off HBr to give 5-ethylthieno[3, 2-d]isothiazole. Lithium aluminum hydride reduces mercaptothienylideneimines to aminomethyl derivatives.