Biomedical subjects
Publications and source records attributed to M Jokić.
The molecule of benzene-1,4-dicarboxamidine or benzdiamidine, C(8)H(10)N(4), reveals C(i) symmetry. Hydrogen bonds utilize the amino groups as double donors, whereas the imino groups act as double acceptors. The network formed is similar to that observed in the crystal packing of terephthalamide.
Bis(LeuOH) (1a), bis-(ValOH) (2a) and bis(PhgOH) (5a) (Phg denotes (R)-phenylglycine) oxalyl amides are efficient low molecular weight organic gelators of various organic solvents and their mixtures as well as water, water/DMSO, and water/DMF mixtures. The organisational motifs in aqueous gels are dominated primarily by lipophilic interactions while those in organic solvents are formed by intermolecular hydrogen bonding. Most of the gels are thermoreversible and stable for many months. However, 2a forms unstable gels with organic solvents which upon ageing transform into variety of crystalline shapes. For some 1a/alcohol gels, a linear correlation between alcohol dielectric constants (epsilon) and gel melting temperatures (Tg) was found. The 1H NMR and FTIR spectroscopic investigations of selected gels reveal the existence of temperature dependent network assembly/dissolution equilibrium. In the 1H NMR spectra of gels only the molecules dissolved in entrapped solvent could be observed. By using an internal standard, the concentration of dissolved gelator molecules could be determined. In FTIR spectra, the bands corresponding to network assembled and dissolved gelator molecules are simultaneously present. This enabled determination of the Kgel values by using both methods. From the plots of InKgel versus 1/T, the deltaHgel values of selected gels have been determined (-deltaHgel in 10-36 kJ mol(-1) range) and found to be strongly solvent dependent. The deltaHgel values determined by 1H NMR and FTIR spectroscopy are in excellent agreement. Crystal structures of 2a and rac-5a show the presence of organisational motifs and intermolecular interactions in agreement with those in gel fibres elucidated by spectroscopic methods.
In the title compound, C20H22N4O4*C2H6OS, two distinct hydrogen-bond systems connect oxalamide groups in one pattern and primary amide groups in the other to form a two-dimensional network perpendicular to the c axis. These hydrophilic layers are joined to the three-dimensional structure through C--H...pi interactions. The hydrogen-bonded waved layers shape holes which are occupied by disordered dimethyl sulfoxide solvent molecules.
The title compound, 2,2'-(oxalyldiimino)bis(3-methylbutanoic acid), C12H20N2O6, possesses a centre of symmetry. In the crystal, molecules are connected by hydrogen bonds between oxamide and carboxyl groups, similar to the pattern of the monoclinic forms of HO-Gly-CO-CO-Gly-OH and HO-Aib-CO-CO-Aib-OH (Gly is glycine and Aib is 2-aminoisobutyric acid). The characteristic torsion angles in the title compound are close to those in peptide alpha-helices.
Novel pyrimido[1,2-a]pyrimidinones 14, 15 and 16 and imidazo[1,2-a] pyrimidinones 19 and 20, designed as conformationally constrained analogues of 1-(3-amino-2-hydroxypropyl)thymine and 1-(2-amino-3-hydroxypropyl)thymine, respective ly, were synthesized by the ring-opening/ ring-closure rearrangement of the corresponding byciclic oxygen-containing amino compounds 12 and 17.
The diastereoisomeric differentiations and anomerizations of 5,6-dihydrothymidine and its anhydro derivatives were studied. In particular, the oxetane ring opening of (5S)-1-(3,5-anhydro-2-deoxy-beta-D-threopentofuranosyl)-5,6-dihydr othymine under acid catalysed conditions substantiated a number of the configurational modifications at the sugar moiety. The 1,3-dipolar cycloaddition to the pyrimidine C(5), C(6)-double bond was intramolecularly facilitated by the activation of 1-(3-azido-2-hydroxypropyl)uracil. (E)- and (Z)-1-Prop-enyl- and properly functionalized 1-propyl-uracil derivatives were also prepared and used for the synthesis of the tetrahydro-oxazolo[3,2-c]pyrimidine-5,6-(4H, 6H)dione and 9,3'-cyclo-3-propyl (or prop-1-enyl)-8-azaxanthine derivatives.
Because of a growing need for the selection, flow of information, and adequate application of scientific information, the presentation of the utilization of databases and their information sources is necessary. An outline of databases and the description of structure and contents of the most important databases are given. The databases are chosen according to the scope of the field they cover in order to supply users with the best possible information in the field of biomedicine. The following databases are included: Biosis Previews, Ca Search, Cancerlit, Clinical Abstracts, Consumer Drug Information Fulltext, De Haen Drug Data, Diogenes, Drug Information Fulltext, Embase, Health Planning & Administration, International Pharmaceutical Abstracts, Life Sciences Collection, Martindale Online, Medline, Mental Health Abstracts, Nursing & Allied Health, Occupational Safety and Health, Pharmaceutical News Index and Smoking and Health.
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