Vol. 14 No. 1(53) (2016)
Published:
2016-03-04
Full Issue
Original Researches
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The study of the three-component interaction between 1-ethyl-1H-2,1-benzothiazin-4(3H)-one 2,2-dioxide, heterylcarbaldehydes and active methylene nitriles
Some peculiarities of the three-component interaction of 1-ethyl-1H-2,1-benzothiazin-4(3H)-one 2,2-dioxide with active methylene nitriles and heterylcarbaldehydes have been described in this article. It has been found that if malononitrile is used, the products of the three-component reaction are 2-amino-4-heteryl-3-cyano-6-ethyl-4,6-dihydropyrano[3,2-c][2,1]benzothiazine 5,5-dioxides irrespective of the heteryl fragment nature in the initial aldehyde. When using ethyl cyanoacetate (as the active methylene nitrile) in the three-component interaction instead malononitrile the reaction lost its selectivity. In this case, depending on the heterylcarbaldehyde, three different types of products were obtained, namely 2-amino-3-alkoxycarbonyl-4-heteryl-4H-pyranes (for pyridine-3-, pyridine-4-carbaldehydes and furan-2-carbaldehyde), thriethylammonium salt of bis(1-ethyl-1H-2,1-benzothiazin-2,2- dioxo-4-ol-3-yl)(2-thienyl)methane (for thiophen-2-carbaldehyde) or ethyl 2-cyano-3-(1H-indol-3-yl)acrylate (for indol-3-carbaldehyde). Formation of a stable triethylammonium salts was considered as the process competitive with formation of 2-amino-4H-pyranes. It has allowes to propose the modiŸed mechanism of 2-amino-4H-pyranes formation. This mechanism includes the stage of forming triethylammonium salts of bis-adducts. According to this mechanism 2-amino-3-ethoxycarbonyl-4-(2-thienyl)-4H-pyrane without any impurity of bis-adduct could be selectively obtained using the three-component interaction. Triethylammonium salts of bis-adducts were obtained by direct interaction of 1-ethyl-1H-2,1-benzothiazin-4(3H)-one 2,2-dioxide with heterylcarbaldehydes in the presence of equimolar amounts of triethylamine. It has been shown that the three-component interaction of 1-ethyl-1H-2,1-benzothiazin-4(3H)-one 2,2-dioxide with active methylene nitriles and heterylcarbaldehydes is a more effective tool in order to obtain condensed 2-amino-4-heteryl-4H-pyranes compared to the stepwise approach. -
The search for new antimicrobial agents from the substituted arylamides of 4-(4-oxo-4H-quinazolin-3-yl)-piperidine-1-carboxylic acids
The methods for the synthesis of the substituted arylamides of 4-(4-oxo-4H-quinazolin-3-yl)-piperidine-1-carboxylic acids using the technologies of the liquid-phase parallel synthesis have been developed. The structure of the compounds obtained has been confi rmed by the data of the instrumental methods of organic analysis. The antibacterial activity of the compounds obtained has been studied using the agar “well” diffusion method against the standard test-strains of microorganisms. The results of the screening performed have shown that all compounds inhibit the growth of Staphylococcus aureus and Bacillus subtilis strains. The strains of Proteus vulgaris and Pseudomonas aeruginosa have been found to be the most resistant. The SAR-analysis of the substituted arylamides of 4-(4-oxo-4H-quinazolin-3-yl)-piperidine-1-carboxylic acids has demonstrated that the presence of the electron-donating substituents in position 8 of the quinazolin-4-one cycle and in position 4 of the aromatic fragment of the urea increases the activity of the compounds of this series against gram-positive bacteria. Such high effi cacy of the lead compounds against the gram-positive bacterial strains can be applied for creating the narrow spectrum antibiotics derived from arylamides of 4-(4-oxo-4H-quinazolin-3-yl)-piperidine-1-carboxylic acids. -
5,6-dihydro-[1,2,4]triazolo[1,5-c]quinazolines. Message 2. [5+1]-cyslocondensation of [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines with aliphatic and aromatic ketones
The reactions of [5+1]-cyclocondensation of [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines with aliphatic and aromatic ketones result in the corresponding 5-R-5-R1-2-aryl-5,6-dihydro-[1,2,4]triazolo[1,5-c]quinazolines with good yields. Modifi cation of the synthetic protocol by variation of the solvent and duration of the reaction does not lead to the changes in target products yields. Conducting of the interaction between [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines and ketones in acetic acid leads to formation of the mixture the corresponding 2-aryl-5-R-5-R1-5,6-dihydro[1,2,4]triazolo[1,5-c]quinazolines and 5-methyl-2-aryl-[1,2,4]triazolo[1,5-c]quinazolin. The compounds mentioned above have been prepared using alternative synthetic approaches, namely via refl uxing of [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines in acetic acid. The formation of 5-methyl-2-aryl-[1,2,4]triazolo[1,5-c]quinazolines occurs as a competitive acylation followed by the condensation process. It can be explained by the low reactivity and spatial structure of the corresponding ketones. The purity and the structure of the compounds synthesized have been proven by the complex of physicochemical methods, including IR-, LC-MS, 1H-, 13C-NMR-spectrometry and elemental analysis. It has been found that the characteristic signal of sp3-carbon atom of position 5 for the compounds synthesized is observed at the 75.57-61.64 ppm. -
Development of the method for quantitative determination of the composition of Ag@Fe3O4 magnetic nanocomposite
The method for quantitative determination of the components of the Ag@Fe3O4 nanocomposite has been developed; it allows simultaneously determining silver and iron in one sample without the stage of taking the aliquot for individual determinations of these components. The method proposed comprises: the use of a considerably smaller quantity of the substance in the test sample; elimination of the need to prepare and standardize the solution of the indicator for silver determination; reduces the labour intensity of the process by saving time and expensive reagents; eliminates the stage of separation of the mixture components, etc. The basis of the method proposed is two conjugated detection procedures –Ag determination by Volhard’s method and Fe (III) determination in magnetite by the method of iodometry. It has been shown that this method allows determining silver without adding the indicator since the second component is magnetite containing bivalent and trivalent iron. The experiment is performed by the action of nitric acid on the sample of Ag@Fe3O4 powder. The acid, in its turn, helps silver to pass into solution and to oxidize Fe2+ ions to Fe3+ being an indicator in this determination. With the simultaneous presence of silver and iron in one sample at Ÿrst silver is quantiŸed, a pale pink colour of the solution above the precipitate appears only after all the silver has been titrated, that means the completeness of its precipitation. The experiment is completed with determination of Fe (III) by iodometry. To assess the validity of determinations the results have been conŸrmed by instrumental methods that are consistent with the results of the titrimetric method developed for quantitative determination of components in magnetically controlled nanocomposites. The relative error of the titrimetric determination does not exceed 0.1-0.2%. -
Amidoximes and their masked derivatives as prodrugs of amidines – arginine mimetics
The literature data concerning the use of amidoximes as prodrugs of amidines – arginine mimics – have been systematized. The advantages of the use of amidoximes as prodrugs that have become a tool for improving physicochemical, biopharmaceutical or pharmacokinetic properties of pharmacologically active agents has been highlighted. The mechanism of their in vivo activation by the mARC-containing N-reductive enzyme system to release the active parent drug of amidoximes has been described. The data on application of the “amidoximes instead of amidines” strategy in the prodrug design have been summarized. The examples of prodrugs with a wide range of biological activities such as antiprotozoal and antithrombotic activity, as well as inhibitors of serine proteases of the sulfonamide type, antiviral prodrugs have been given. They are either introduced into production or are at the stage of clinical trials. In addition, the synthetic methods for amidoximes, and the synthesis of the known prodrugs have been also shown. The new approach to the drug modifi cation – the use of double prodrugs has been described. This strategy allows to obtain the derivatives with less basicity and improved lipophilicity,therefore, with better bioavailability. The synthesis of a single commercial oral thrombin inhibitor dabigatran etexilate (Pradaxa) as a dabigatran double prodrug, as well as amidine and amidoxime derivatives of the antiviral oseltamivir (Tamifl u) has been presented. 1,2,4-Oxadiazoles, masked amidoxime prodrugs have been used in the design of potential antimalarial, antifungal drugs and in order to obtain new oral GPIIb/IIIa antagonists. -
The synthesis, hypoglycemic activity and acute toxicity of new imidazole-thiazolidines hybrid structures
The article presents a brief description of diabetes type 2 as a disease related with carbohydrate metabolism disorder mainly caused by insulin resistance and relative insulin defi ciency. It has been noted that pathologies may appear under the action of drugs of the glitazone group; it is a major cause for systematic search for new bioactive and safe compounds with the hypoglycemic action. Considering the wide range of the biological activity of imidazole derivatives and 1,3-thiazolidine the synthesis of new hybrid structures – 5-[(1-aryl-4-chloro-1H-imidazole-5-yl)methylene]-1,3-thiazolidine-2,4-diones and their exohydrated analogues – 5-[(1-aryl-4-chloro-1H-imidazole-5-yl)methyl]-1,3-thiazolidine-2,4-diones has been carried out. A preparative suitable scheme for their obtaining has been proposed, it is based on condensation of available 1-aryl-4-chloro-5-formylimidazoles with1,3-thiazolidine-4-one and further hydrogenation of the exocyclic ylidene bond formed. The results of biomedical studies of the compounds obtained in the doses of 100, 10 and 1 mg/kg have shown that they have a strong hypoglycemic activity, which exceeds the effect of test drug pioglitazone by 55%. The acute toxicity (LD50) of 5-{[1-(4-tolyl)-4chloro-1H-imidazole-5-yl]methylene}-1,3-thiazolidine-2,4-dione is 1292.92 mg/k when injected intraperitoneally. -
[(N-Aryl)piperazinil]bythylpyrimidine derivatives with neurotropic and actoprotective properties
In this study the potential ligands of 5-HT1A receptors – arylpiperazines containing the residues of tetrahydropyrimidine as terminal fragments, compounds (1-6) and dihydropyrimidine – (7) have been synthesized. The structures of compounds 1-7 have been confi rmed by IR-spectroscopy, mass spectrometry and 1H-NMR-spectroscopy. Substances 2, 3, 4 and 7 inhibit the specifi c binding of the radioligand [3H]8-OH-DPAT with 5-HT1A receptors; it has been found that they have a pronounced affi nity for these receptors. In the confl ict situation test compounds of 1-5 and 7 showed anxiolytic properties, whereas phenylpiperazinil- and о-tolylpiperazinilbutyl-4-methyl-5-izopropyl-1,2,3,-6-tetrahydropyrimidine-2-thio-6-ones (1 and 2) exceeded the known drug buspirone by the level of the anxiolytic activity. The absence of this activity in compound 6 is probably due to the differences of substituents at N1 atom of the pyrimidine nucleus of compound 6 and other compounds of this series. It has been shown that on the model of hyperthermia all of these compounds in the dose range of 0.04-0.1 mg/kg possessed a high actoprotective activity increased the rat capacity work by 1.4-2.5 times compared to the control. The most active compound 3 in the ED50 dose of 0.04 mg/kg increased the duration of swimming in rats by 2.2 times (122%) compared to bemithylum. Some of the compounds (15 mg/kg) showed antihypoxic activity on the models of hemic (compounds 2-4, 7) and normobaric hypoxia (compounds 1, 2, 6) and exceeded bemithylym (33.5 mg/kg) by their activity. The compounds synthesized are low toxic with the LD50 value of 150-250 mg/kg. -
The synthetic method for 1-(phenyl)alkyl-3-acyl-1,2,8-triazaspiro[4.5]decanes
Piperidines spiro-fused to other heterocycles and being structural elements of pharmacologically active molecules can be considered as “preferred fragments” of metabotropic receptor ligands. The method for obtaining 1,2,8-triazaspiro [4.5]decane comprising spiroannelation of 1,4-dihydropyridine and pyrazolone cycles. When heating of 1-(phenyl)alkyl-4-[2-[2-arylhyqrazono]-1,3-dioxobutyl]pyridinium halide in pyridine or by reacting of 1-(phenyl)alkyl-4-[2-[2-arylhyqrazono]-1,3-dioxobutyl]pyridinium halides and 1-(phenyl)alkyl-4-{1,3-dioxo-3-phenyl-2-[2-(4-methylphenyl)hydrazono]propyl}pyridinium halides with diisopropylethylamine at 25°C the intramolecular reductive alkylation of the electrophilic pyridinium cation occurs forming 1-(phenyl)alkyl-3-acyl-1,2,8-triazaspiro[4.5]decanes, which are solid coloured substances. The spectral properties of the cyclization products have been studied; formation of the spiro-fused system and the presence of the 1,4-dihydropyridine fragment have been determined. Confi rmation of their structure has been obtained by carrying out the X-ray diffraction of 3-acetyl-8-benzyl-1-phenyl-1,2,8-triazaspiro[4.5]deca-2,6,9-trien-4-one crystal, which, in its turn, has clearly confi rmed orthogonality of the spiro-fused planes. The dihydropyridine ring in the molecule is not fl at and is located in the half-chair conformation with deviation of carbon spiro atom from the plane of the rest atoms of the cycle. This is due to formation of the intramolecular C-H...π hydrogen bond. -
The synthesis and biological properties of hydroxy-(alkoxy)substituted anilides of 4-hydroxy-2,2-dioxo-1h-2λ6,1-benzothiazine-3-carboxylic acids
Continuing the search for new biologically active substances of 2,1-benzothiazines a series of the corresponding anilides of 1-R-4-hydroxy-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylic acids has been synthesized by the reaction of alkyl-1-R-4- hydroxy-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylates and the equimolar quantities of hydroxy- and alkoxy-substituted anilines. Their structure has been confi rmed by the data of elemental analysis, NMR 1H spectroscopy (1H and 13C), as well as mass spectrometry. All compounds obtained were subjected to pharmacological screening to identify their analgesic properties. Testing was carried out in non-pedigree male rats using the standard model of the thermal tail-fl ick (tail immersion test) in parallel and in comparison with the structurally related drugs – Meloxicam and Piroxicam. Among the substances studied the potent analgesics have been found. When administered orally in the dose of 20 mg/kg they several times exceed the reference medicines in their analgesic effect and are of interest for the profound research. The study of the effect of the compounds synthesized on the urinary function of the kidneys has shown that in this case transition from quinoline analogues to 2,1-benzothiazine ones is accompanied by some decrease in diuretic properties although some compounds increase diuresis at the level of hydrochlorothiazide in a much lower dose. -
The synthesis of new phosphonopeptidomimetics and their effect on the functional cardiac output
The article presents the synthesis of new phosphorylated peptidomimetics, and the biological activity of the compounds synthesized has been assessed for the fi rst time on the experimental animals – male rats. On the basis of a diethyl ester of 1-benzoylamino-2,2,2-trihloroethylphosphonic acids a novel derivative of 1,3-oxazol-4-phosphonic acid diethyl ester containing the residue of methylaminoethan-1-ol in position 5 of the oxazole ring has been synthesized. The optimal conditions for cleavage of the 1,3-oxazole ring in the acidic medium with formation of phosphorylated peptidomimetics have been found. Thus, when treating it with 85 % aqueous trifl uoroacetic acid a diethyl ester of {benzoylamino[(2-ydroxyethyl)carbamoyl]methyl} phosphonic acid has been obtained, and the action of hydrogen chloride under anhydrous conditions gives a diethyl ester of {benzoylamino[(2-chloroethyl) carbamoyl]methyl} phosphonic acid. The method developed is very convenient and preparative because reactions proceed in mild conditions without formation of undesirable by-products. Moreover, peptidomimetics are isolated with high yields, and their isolation does not require chromatography. Monitoring of different functional parameters of cardiac hemodynamics was performed in rats in vivo using a microcatheter and the Millar Pressure-Volume System. The study of the effect of the compounds obtained on the cardiac output has shown that their intraperitoneal introduction results in the heart rate decrease and stimulation of the contractile activity of the myocardium.
