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Carbamate Derivatives (carbamate + derivative)
Selected AbstractsChemInform Abstract: Synthesis of Carbamate Derivatives of Coumarin and Chromene.CHEMINFORM, Issue 9 2009A. V. Velikorodov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis of Peptidyl Ureas Using p-Nitrophenyl-(9-fluorenylmethoxy Carbonylamino)methyl Carbamate Derivatives.CHEMINFORM, Issue 49 2004Basanagoud S. Patil No abstract is available for this article. [source] Evidence of a functional requirement for a carbamoylated lysine residue in MurD, MurE and MurF synthetases as established by chemical rescue experimentsFEBS JOURNAL, Issue 22 2001Sébastien Dementin Enzymes MurD, MurE, MurF, folylpolyglutamate synthetase and cyanophycin synthetase, which belong to the Mur synthetase superfamily, possess an invariant lysine residue (K198 in the Escherichia coli MurD numbering). Crystallographic analysis of MurD and MurE has recently shown that this residue is present as a carbamate derivative, a modification presumably essential for Mg2+ binding and acyl phosphate formation. In the present work, the importance of the carbamoylated residue was investigated in MurD, MurE and MurF by site-directed mutagenesis and chemical rescue experiments. Mutant proteins MurD K198A/F, MurE K224A and MurF K202A, which displayed low enzymatic activity, were rescued by incubation with short-chain carboxylic acids, but not amines. The best rescuing agent was acetate for MurD K198A, formate for K198F, and propionate for MurE K224A and MurF K202A. In the last of these, wild-type levels of activity were recovered. A complementarity between the volume of the residue replacing lysine and the length of the carbon chain of the acid was noted. These observations support a functional role for the carbamate in the three Mur synthetases. Experiments aimed at recovering an active enzyme by introducing an acidic residue in place of the invariant lysine residue were also undertaken. Mutant protein MurD K198E was weakly active and was rescued by formate, indicating the necessity of correct positioning of the acidic function with respect to the peptide backbone. Attempts at covalent rescue of mutant protein MurD K198C failed because of its lack of reactivity towards haloacids. [source] Separation of chiral phosphorus compounds on the substituted ,-cyclodextrin stationary phase in normal-phase liquid chromatographyCHINESE JOURNAL OF CHEMISTRY, Issue 4 2000Chen Hyi Abstract The separation of enantiomers of a series of eighteen novel nitrogen mustard linked phosphoryl diamide derivatives was investigated on the prepared phenyl carbamate derivative ,-cyclodextrin bonded phase in normal-phase HPLC. Some of the enantiomers could be separated in baseline. The chiral recognition mechanism was also suggested for the separation of chiral phosphorus organic compounds. [source] Pharmacokinetics of 4-aminopyridine derivatives in dogsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2009N. J. OLBY Blockade of potassium channels with 4-aminopryidine (4-AP) restores conduction to demyelinated axons and improves function. Unfortunately, 4-AP causes adverse effects and its clinical effects are unpredictable and limited. Derivatives of 4-AP have been tested in models of spinal cord injury in guinea pigs; three derivatives (methyl-, ethyl- and t -butyl carbamate derivatives) showed promise. This study investigates the safety and pharmacokinetics of these derivatives in dogs. Each derivative was administered orally to dogs starting at doses below effective doses in guinea pigs, and increasing the dose on sequential days. Routine blood work was performed prior to and 24 h after drug administration, blood samples were collected at intervals over 24 h after drug administration, and dogs were monitored for side effects. Derivative plasma levels were determined using high-pressure liquid chromatography. Cerebrospinal fluid (CSF) samples were taken to determine CSF levels. No adverse effects were seen even when using doses higher than those that improved conduction in spinal cord injured guinea pigs. Peak plasma levels occurred at 36.6 (ethyl), 87 (t -butyl) and 175 (methyl) min and plasma level was related to drug dose. Penetration of the central nervous system (CNS) was good, with CSF levels higher than plasma levels for the t -butyl derivative. [source] Synthesis and Stability in Biological Media of 1H -Imidazole-1-carboxylates of ROS203, an Antagonist of the Histamine H3 ReceptorCHEMISTRY & BIODIVERSITY, Issue 1 2008Mirko Rivara Abstract A series of carbamate derivatives of the H3 antagonist ROS203 (1) were prepared, and their lipophilicity and steric hindrance were modulated by introducing linear or branched alkyl chains of various lengths. In vitro stability studies were conducted to evaluate how structural modulations affect the intrinsic reactivity of the carbamoyl moiety and its recognition by metabolic enzymes. Linear alkyl carbamates were the most susceptible to enzymatic hydrolysis, with bioconversion rates being higher in rat liver and plasma. Chain ramification significantly enhanced the enzymatic stability of the set, with two derivatives (1g and 1h) being more stable by a factor of 8,40 than the ethyl carbamate 1a. Incubation with bovine serum albumin (BSA) showed a protective role of proteins on chemical and porcine-liver esterase (PLE)-catalyzed hydrolysis. Ex vivo binding data after i.v. administration of 1h revealed prolonged displacement of the labeled ligand [3H]-(R)- , -methylhistamine ([3H]RAMHA) from rat-brain cortical membranes, when compared to 1. However, the high rates of bioconversion in liver, as well as the chemical instability of 1h, suggest that further work is needed to optimize the enzymatic and chemical stability of these compounds. [source] | ||||||||||