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J Valentová

Publications and source records attributed to J Valentová.

7 recordsLinked to original sources
PubMed2005

[Blockers of beta-adrenergic receptors--a group of chiral agents stereoselective synthesis of beta-blockers].

Besides chromatographic methods and biocatalyzed reactions, another alternative method of obtaining enantiomeric forms of beta-blockers is stereoselective synthesis. This paper links up with two preceding surveys concerning beta-blockers--groups of chiral agents and presents a survey of the hitherto published enantioselective syntheses of (R)- and (S)-enantiomers of beta-blockers. In the group of arylaminoethanols, mainly selective reduction of prochiral ketones in the presence of metallic complexes is used in this type of synthesis. Enantiomerically pure beta-blockers of the aryloxyaminopropanol type are synthesized by means of a reaction of pertinent phenols with different chiral precursors, such as (R) and (S)-chloromethyloxirans, (S)-glycidoltosylate, (S)- or (R)-2,3-O-isopropylideneglyceroltosylate, E-(2S,3S)-3-trimethylsilylglycidol and (S)-3-terc-butyl-5-phenyl-oxazolidine-5-ylmethanol. Many of these chiral semiproducts can be prepared from natural substances, such as D-mannitol and L-ascorbic acid.

Adrenergic beta-Antagonists↗
PubMed2004

[Adrenergic beta-receptor blockers--a group of chiral drugs: enantioseparation in the group of beta-blockers].

The preparation of pure individual enantiomers represents a topical problem from the standpoint of efficacy and safety of drugs. This paper continues in the preceeding review of the blockers of beta-adrenergic receptors as a group of chiral drugs, which is concerned with different pharmacodynamic, pharmacokinetic, and toxicological effects of individual enantiomers of this group. The review paper pays attention to the problems of enantioseparation of this group of chiral drugs, listing individual examples of the methods of enantioseparation, such as crystallization, biocatalysis, chromatographic methods (HPLC, GC, TLC), capillary electrophoresis, and the method of nuclear magnetic resonance (NMR). The individual methods of enantioseparation including enantioseparation in biological material (urine, serum) are illustrated on examples on beta-blockers used in clinical practice (e.g., propranolol, atenolol, metoprolol) as well as potential agents of this group of drugs.

Adrenergic beta-Antagonists↗
PubMed2004

[Chiral switch: pure enantiomers of drugs instead of racemic mixtures].

Chirality of drugs, particularly the comparison of efficacy of enantiomers and their racemic mixtures, has become an object of serious interest of pharmaceutical researchers in recent ten or fifteen years. Advances in chemical technologies connected with the synthesis, separation, and analysis of pure enantiomers from racemates, together with administrative regulatory measures, have resulted in an increase in the number of newly registered chiral drugs containing only one of the enantiomers. Besides new chemical entities, many "old" racemates are being re-evaluated as potentially new sources of pure enantiomers which should improve the therapeutic profile of the drug. Due to this replacement of a racemic mixture with a pure enantiomer, the literature lists both drugs containing a racemate and drugs containing only one of the enantiomers. Nevertheless, the required therapeutic effect is not always achieved, and unexpected undesirable effects have also occurred. The paper summarizes therapeutic and economic problems concerning chiral switch drugs.

Chemistry, Pharmaceutical↗
PubMed1994

[Radioprotective effects of basic copper carboxylate complexes].

The radioprotective activity of eight selected copper (II) carboxylates--Cu (RCOO)2.nL (R = alkyl, aryl, 2-furyl and 2-thienyl; L usually represents water)--was assayed in a model of lethally gamma-irradiated (9 Gy, 0.97 Gy/min) mice. The compounds tested were applied (as solutions in saline) s.c. in three single doses of 20 mumol/kg 48.24 and 6 h before irradiation. The highest radioprotective effects were measured by survival of mice achieved after premedication of animals with copper (II) 2-thenoate monohydrate (77%), copper (II) acetylsalicylate (64%), copper (II) 2-methoxybenzoate monohydrate (62%) and copper (II) acetate monohydrate (54%). On the other hand, survival of vehicle-pretreated mice was only 10%. The observed biological properties of complexes are discussed in relation to their structures.

Animals↗
PubMed1993

[Anti-ulcer effectiveness of mono- and dibasic carbamates with local anesthetic effects].

An evaluation of anti-ulcer effects of mono- and dibasic carbamate local anaesthetics was performed using two experimental models of gastric ulcers, i.e. those induced by stress, or by ligation of the pylorus. These models have been found not to be identical. In the case of stress-induced ulcers, no experimental animal died as compared to the second experimental group with a 30% mortality rate due to the more frequent occurrence of ulcer perforations. Result similarities of both models could only be found with respect to the range of damage of the mucous membrane of the stomach. A premedication with a majority of basic carbamates decreased the incidence and range of ulcer lesion. The anti-ulcer activity of monobasic carbamates was more significant when compared with dibasic compounds.

Anesthetics, Local↗
PubMed1993

The influence of carbamate local anesthetics on the occurrence of experimental gastric ulcers.

Evaluation of the antiulcer effects of a series of 2-piperidineethylesters of o-alkoxy-substituted phenylcarbamic acids were performed using two experimental models of gastric ulcers, e.g. induced by stress or by ligation of the pylor. It was found that these models were not identical. In the case of stress-induced ulcers, no experimental animal died as compared to the second experimental group with a 30% mortality rate due to the more frequent occurrence of ulcer perforations. Result similarities of both models could only be found with respect to the range of damage of the mucous membrane of the stomach. A premedication of rat with basic carbamates in the dose 20 mg.kg-1 p.o. resulted in a reduced incidence of stress- and ethanol-induced ulcerous lesions. The most significant antiulcer activity was found using compounds designated as the No. XIII, XVI and XIX. Pretreatment of rats with basic carbamates in the case of Shay ulcers has again resulted in a reduced range of ulcer lesions which was most expressive using compounds No. XVI and XIX.

Anesthetics, Local↗