Vol. 13 No. 3(51) (2015)
Published:
2015-09-10
Full Issue
Original Researches
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The reserved-phase HPLC study of the complexation of 5,17-bis-(N-tolylimino-methyl)-25,27-dipropoxycalix[4]arene with aromatic carboxylic acids
The Host-Guest complexation of 5,17-bis-(N-tolyliminomethyl)-25,27-dipropoxycalix[4]arene with a number of aromatic carboxylic acids has been studied by reversed-phase high-performance liquid chromatography. The mobile phase was acetonitrile-water (80/20, v/v) with addition of 0.1% formic acid. The column was LiChrosorb RP 18, the UV detector operated at λ = 254 nm and at 26°C. The main chromatographic characteristics (retention time t[sub]R[/sub] and capacity factor k’) of the aromatic carboxylic acids have been determined. The lipophilicity values of log P of carboxylic acids, as well as the binding constants K[sub]A[/sub] (387-941 M[sup]-1[/sup]) and Gibbs free energies ∆G (-14.74 – -16.94 kJ/mol) of the calixarene complexes with aromatic carboxylic acids have been calculated. The molecular modelling (Hyper Chem, version 8.0) of the calixarene complexes has revealed the presence of hydrogen bonds between carboxylic groups of the acids and nitrogen atoms of imino groups at the upper rim or oxygen atoms of hydroxyl groups at the lower rim of the calixarene macrocycle. The infl uence of log P lipophilicity of acids on K[sub]A[/sub] values of the calixarene complexes has been assessed. The linear dependence of the binding constants on the acid lipophilicity indicates a signifi cant role of solvophobic interactions on the complexation process. The relationship between supramolecular (K[sub]A[/sub]) and physicochemical (molecular weight, log P, pKa) characteristics of acids has been found. The binding constants K[sub]A[/sub] of the complexes increase with increase of their molecular weight and log P values. -
The synthesis and analgesic properties of N-(benzyl)-2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxamides
Continuing the search for new analgesics among derivatives of azahetarylcaboxylic acids by the reaction of ethyl 2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylate and benzylamines in boiling ethanol the corresponding group of N-(benzyl)-2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxamides has been synthesized. The structure of the compounds obtained has been confirmed by the data of elemental analysis and NMR 1H spectroscopy. It is noted that the signals of aromatic protons of pyrido-pyrimidine nuclei are shifted downfield and generally for a typical AMX spin system. At the same time, the signals of aromatic protons of benzilamide fragments on the contrary are shifted upfield in all cases and focused on very narrow segments of the spectra, thereby undergoing strong distortion. According to the results of the primary pharmacological screening it has been found that using the standard model of “acetic acid writhings” all N-(benzyl)-2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxamides without exception have analgesic properties to a greater or lesser degree. Practically the same regularities of the benzylamide fragment structure –biological effect relationship as in the case of 4-hydroxyquinolin-2-ones analogues have been found. Based on it the conclusion about bioisosterism of 4-hydroxyquinolin-2-one and 2-hydroxy-9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine nuclei has been made.
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The synthesis of 4-thiazolidinone derivatives using 2-(4-R-2-formylphenoxy)-N-(R’-phenyl)acetamides and their anti-inflammatory activity
The research is devoted to the rational design of new non-steroidal anti-inflammatory drugs (NSAIDs) using the 4-thiazolidinone “core”. A series of 2-(4-R-2-formylphenoxy)-N-(R’-phenyl)acetamides has been synthesized from salicylic aldehydes for structural modifications of basic heterocycles. The aldehydes obtained are active carbonyl agents and suitable “building blocks” for the focused synthesis of biologically active compounds. Ylidene derivatives of 2-thioxo-4-thiazolidinone and 2-(4-hydroxyphenyl)imino-4-thiazolidone have been synthesized in the Knoevenagel reaction conditions. The one-pot reaction between 3(5)-merkapto-1,2,4-triazoles, chloroacetic acid and the salicylic aldehyde derivatives synthesized have been used for the synthesis of 5-ylidene-thiazolo[3,2-b][1,2,4]triazol-6-one. Parameters of acute toxicity and the anti-exudative activity (carrageenin paw edema test) have been studied for the ylidene derivatives synthesized. It has been found that all compounds synthesized demonstrate the anti-exudative activity, and some “structure – acute toxicity – anti-exudative activity” relationships have been analyzed. Based on the results of in vivo studies the lead compound – 4-{2-[4-chloro-2-(6-oxothiazolo[3,2-b][1,2,4]triazole-5-ylidenemethyl)-phenoxy]- acetylamino}-benzoic acid ethyl ester that demonstrates the anti-exudative activity equivalent to the classic NSAID Diclofenac has been identified, it has a low level of toxicity and can be recommended for the profound study.
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The synthesis of 6-R-2,2,4-trimethyl-1,2-dihydroquinoline- and 6-R-4-R’-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline-8-carboxylic acids – the structural analogues of helquinoline
The peculiarities of the oxidation reaction of substituted (5,6-dihydro)-4,4,6-trimethyl-4H-pyrrolo[3,2,1-ij] quinoline-1,2-diones have been investigated. 6-R-2,2,4-trimethyl-1,2-dihydroquinoline-8-carboxylic acids and 6-R-4-R’-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline-8-carboxylic acids, which are structural analogues of the natural antibiotic Helquinoline ((2R,4S)-4-methoxy-2-methyl-1,2,3,4-tetrahydroquinoline-8-carboxylic acid), have been obtained by oxidation of 8-R-4,4,6-trimethyl-4H-pyrrolo[3,2,1-ij]quinoline-1,2-diones and their hydrogenated analogues – 8-R-6-R’-4,4,6-trimethyl-5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinoline-1,2-diones. It has been shown that 8-R-6-R’-4,4,6-trimethyl-5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinoline-1,2-diones and 8-R-4,4,6-trimethyl-4H-pyrrolo [3,2,1-ij]quinoline-1,2-diones are oxidized similar to isatin with opening of the pyrrole-1,2-dione fragment and subsequent decarboxylation, and the presence of bulky substituents – gem-dimethyl groups in the second position of the hydroquinoline cycle has no steric effect on the process. Moreover, it has been found that oxidation of 8-R-4,4,6-trimethyl-4H-pyrrolo[3,2,1-ij]quinoline-1,2-diones proceeds selectively with opening the pyrrole-1,2- dione fragment without affecting the multiple bond of the dihydroquinoline cycle, polymerization also does not occur on it. The structure of 6-R-4-R’-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline-8-carboxylic acids and 6-R-2,2,4-trimethyl-1,2-dihydroquinoline-8-carboxylic acids has been confirmed by 1H NMR and 13C NMR spectroscopy, mass spectrometry and elemental analysis. With the help of mass spectroscopy it has been shown that the heterocyclic fragment of 6-R-2,2,4-trimethyl-1,2-dihydroquinoline-8-carboxylic acids is more stable compared to the fragment of 6-R-4-R’-2 2,4-trimethyl-1,2,3,4-tetrahydroquinoline-8-carboxylic acids.
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N-acylation of amino-9,10-anthraquinones by the system of strong carboxylic acid – ammonium thiocyanate
The significance of the acylation reaction of amines is presented in the literary reference information. The products of the reaction of the corresponding amides are important intermediates in obtaining practically useful compounds. It has been shown that the most common methods of acylfunctionalization of amines are acetylation, trifluoroacetylation and formylation, usually acid anhydrides or chlorides are used as acylating reagents in these reactions in the presence of highly toxic and expensive catalysts. The authors have developed an approach to the synthesis of a number of N-acylated amino-9,10-anthraquinones, which is based on the use of a new acylation system consisting of a strong organic acid and ammonium thiocyanate. It has been determined that 1-amino-9,10-anthraquinone and its derivatives in the presence of the two-fold excess of ammonium thiocyanate can be acetylated only by formic and trifluoroacetic acids. 2-Amino-9,10-anthraquinone additionally can be acetylated by mercaptoacetic and acetic acids. The scheme of the reaction discovered has been proposed, it involves in situ generation of ammonium acetate from carboxylic acid and ammonium thiocyanate, which serves as the acylating reagent.
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The synthesis and the antitubercular activity of 1-benzyl-4-hydroxy-2-oxo-1,2,5,6,7,8-hexahydroquinoline-3-carboxamides
Unfortunately, tuberculosis still remains a cause of high mortality in humans and in modern conditions it has become a global health problem. Continuing the search for new antimycobacterial agents among the amidated derivatives of 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acids the corresponding group of 1-benzyl-4-hydroxy-2-oxo-1,2,5,6,7,8-hexahydroquinoline-3-carboxamides has been synthesized by the reaction of ethyl 1-benzyl-4-hydroxy-2-oxo-1,2,5,6,7,8-hexahydroquinoline-3-carboxylate and anilines or hetarylamines in DMF at 130°C. The chemical structure of the compounds obtained has been confirmed by the data of elemental analysis, NMR 1H spectroscopy and mass spectrometry. It has been noted that the 1H NMR spectra can reliably confirm the presence of the basic functional groups by their corresponding chemical shift, the integrated intensity and multiplicity of signals. It has been shown that under the influence of the electron impact the molecular ions of all the compounds studied undergo the primary fragmentation in two directions: with breaking the amide bond or the quinolone nucleus – the carbamide moiety bond. According to the data of microbiological tests among 1-benzyl-4-hydroxy-2-oxo-1,2,5,6,7,8-hexahydroquinoline-3-carboxamides synthesized the substances that are capable of inhibiting actively the growth of Mycobacterium tuberculosis H37Rv in low concentration have been identified, and therefore, they are of interest for further research.
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The synthesis, computer prediction of the biological activity and the acute toxicity of 1-Ar-4-R-[1,2,4]triazolo[4,3-a] quinazolin-5(4H)-ones
Using the PASS programme computer prediction of the biological activity of 1-Ar-4-R-[1,2,4]triazolo[4,3-a] quinazolin-5(4H)-ones has been performed; it has allowed to identify the types of the biological activity of the compounds studied and sort out the most promising compounds 5{1-20} with the potential anti-asthmatic and anti-allergic activity. Prediction of the acute toxicity of 1-Ar-4-R-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-ones 5{1-20} has been carried out by the GUSAR software, which allows to refer them to slightly toxic (toxicity class 4) or practically nontoxic (toxicity class 5) substances. The synthesis of the most promising compounds 5{1-20} studied іn silico for the biological activity and the acute toxicity has been conducted by interaction of the corresponding 2-hydrazinoquinazolin-4(3H)-ones 1{1-5} with imidazolides 3{1, 2} of aromatic acids 2{1, 2}, or with aromatic aldehydes 4{1, 2} followed by oxidation in the presence of FeCl3. The structure of the compounds 5{1-20}synthesized has been proven by the data of the elemental analysis and 1H NMR spectroscopy. The compounds obtained are promising objects for further investigations as slightly toxic or nontoxic substances with the potential anti-asthmatic and anti-allergic activity.
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The alkylation reaction of aromatic acidshydrazides with (±)-cis-3-dichloromethyl-1,2,2-trimethylcyclopentancarboxylic acid
The article describes the study of the alkylation reaction of aromatic acids hydrazides with (±)-cis-3-dichloromethyl-1,2,2-trimethylcyclopentancarboxylic acid. The acid mentioned is a new substance obtained by oxidative cleavage of racemic camphor in the tetrachloromethane medium according to the method described earlier and modified by us. As a result of alkylation of aromatic acids hydrazides, a series of 3-{[2-(R-carbonyl)hydrazinylidene] methyl}-1,2,2-trimethylcyclopentancarboxylic acids has been obtained with the yields of 77-88%. According to the data of 1H NMR spectra almost all products are E-isomers. The reaction of alkylation of anthranilic hydrazide proceeds with formation of the 1,2,3,4-tetrahydroquinazolin-4-one cycle and obtaining of (±)-cis-3-(3-аmіnо-1,2,3,4-tetrahydroquinazolin-4-оn-2-yl)-1,2,2-trimethylcyclopentancarboxylic acid. The composition of the compounds synthesized has been proven by elemental analysis , and their structure has been confirmed by 1H NMR spectroscopy. According to the results of PASS prediction the compounds synthesized are otential diuretic, antiviral and antibacterial agents. The synthetic studies conducted show the possibility of using (±)-cis-3-dichloromethyl-1,2,2-trimethylcyclopentancarboxylic acid as a building block for extension of a number of biologically active substances synthesized in our previous studies on the basis of (±)-cis-1,2,2-trimethylcyclopentan-1,3-dicarboxylic (camphoric) acid.
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The study of degradation products of chlorpromazine hydrochloride by the method of liquid-mass spectroscopy in drugs for injection
The analysis of model samples of the drug Aminazin has been performed, its active substance is chlorpromazine hydrochloride. These model solutions were subjected to sterilization with previous exposure at room temperature. It has been found that depending on duration of the exposure during sterilization the degradation of the drug occurs in two possible ways – with formation of opalescence or without it. The schemes of degradation with formation of either one product – chlorpromazine sulfoxide, or some products – chlorpromazine sulfoxide, chlorpromazine N-oxide, nor-chlorpromazine and others have been proposed. It has been found that opalescence of solutions is caused by formation of degradation products – chlorpromazine N-oxide and norchlorpromazine that are slightly soluble in water. The analysis of model samples was performed using the liquid chromatography/mass spectrometry methods developed by the authors. In the course of analysis the molecular weights corresponding to the abovementioned products were obtained. Therefore, the experimental confirmation of the chemes of degradation proposed has been obtained. As the result of the research conducted the chromatographic method for detection of impurities using liquid chromatography/mass spectrometry has been developed, and the main ways of degradation of chlorpromazine hydrochloride in aqueous solutions have been determined. According to the result of the research the recommendations to the manufacturing process have been developed, and measures for optimizing the composition of the drug have been proposed.
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The synthesis and physicochemical properties of 2-(5-methoxyphenyl-1H-1,2,4-triazole-3-ylthio) acetonitriles and their iminoethers
With the purpose of further search of biologically active substances among 5-(2-, 3-, 4-methoxyphenyl, 3,4,5- trimethoxyphenyl)-3-thio-1,2,4-triazoles and their derivatives 10 new compounds have been obtained. Acetonitrilothio- 1,2,4-triazoles have been synthesized by alkylation of 5-(2-, 3-, 4-methoxyphenyl and 3,4,5-trimethoxyphenyl)- 3-thio-1,2,4-triazoles with halogenonitriles; the primary computer pharmacological screening has shown that the class of compounds mentioned can show such types of the pharmacological activity as antitumor, antiinflammatory and antioxidant ones. Alkylation of 5-R-1,2,4-triazole-3-thiols has been carried out in the medium of anhydrous alcohol or aprotic solvents. It has been found that replacement of the alcoholic solvent by the aprotic one increases the quantitative yield of 5-R-1,2,4-triazol-3-thioacetonitrile; in aprotic solvents the presence of impurities of alkaline hydrolysis products is not practically observed. Iminoethers of 2-(5-(2-, 3-, 4-methoxyphenyl and 3,4,5-trimethoxyphenyl)-1H-1,2,4-triazole-3-ylthio)acetatic acids have been synthesized by saturation of 2-(5-(2-, 3-, 4-methoxyphenyl and 3,4,5-trimethoxyphenyl)-1H-1,2,4-triazol-3-ylthio)acetonitriles with the flow of dry in the alcoholic medium when constant cooling the reaction mixture to –5ºC. It has been found by the method of HPLC/DAD-MS that the qualitative yield of the target product depends on the maintenance of the temperature mode of the reaction mixture. The structure and individuality of the molecules of the substances synthesized have been proven by the method of 1H NMR-spectroscopy and HPLC/DAD-MS.
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Interaction between palladium(II) ions and asparagine in aqueous solutions
The interaction between Pd(II) and asparagines (Asn) in aqueous solutions with the physiological concentration of chloride ions (0.15 mol/L KCl) has been studied by election spectroscopy and pH potentiometry depending on the ratio of Pd(II):Asn and pH. The formation of equimolar and bisligand complexes has been found where the Asn molecule is coordinated to the central metal ion in a bidentate fashion either by the amine group nitrogen atom and the carboxyl group oxygen atom or by the nitrogen atoms of the amine group and the deprotonated amide group. In the case of bidentate coordination of Asn in complexes with the ratio of metal : ligand = 1 : 1, the Pd(II) coordination sphere is complemented by two chloride ions. The composition of the first coordination sphere of Pd(II) complexes has been characterized on the basis of the position of the absorption band maximum in the electronic spectra of solutions. By the PSEQUAD programme the formation constants of Pd(II) asparaginate complexes: lgβ [PdLCl2]- = 19.36 (2); lgβ [PdLH-1Cl2]2- = 13.63 (1); lgβ [PdL2] = 25,99 (2); lgβ [PdL2H-1]- = 19.97 (4); lgβ [PdL2H-2]2- = 12.78 (4) have been calculated taking into account the concentration of chloride ions. Based on the equilibrium concentration distribution diagrams constructed for the complexes it has been shown that at the physiological values of pH and the chloride ion concentration the complexes [PdLH-1Cl2]2- in the ratio of metal : ligand = 1 : 1 and [PdL2H-1]-, [PdL2H-2]2- in the ratio of metal : ligand = 1 : 2 predominate in solutions.
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A convenient approach to the synthesis of substituted 2-(methylamino)quinoline-3-carboxamides
The paper is devoted to the synthesis of new 2-(methylamino)quinoline-3-carboxamide derivatives by the pyrimidine cycle hydrolytic cleavage of pyrimido[4,5-b]quinoline-2,4(1H,3H)-diones. These later were synthetized in high yields by interaction of available 1,3-dimethyl-6-piperidinyl-5-formyluracil with aromatic amines. The reactions with participation of ortho- and para-substituted aromatic amines proceed regioselectively to give 1,3-dimethylpyrimido[4,5-b] quinoline-2,4(1H,3H)-diones with substituents in positions 7 and 9 of the heterocycle. The use of metha-methoxyand metha-fluoroaniline leads to the mixture of 6- and 8-substituted 1,3-dimethylpyrimido[4,5-b]quinoline-2,4(1H,3H)- diones, which under basic conditions were cleaved into amides of quinoline-3-carboxylic acid. The mixture of 2-(methylamino)quinoline-3-carboxamides obtained was separated by column chromatography. Application of the correlation NMR spectroscopy method (NOESY, COSY, HSQC, HMBC) has allowed to reliably determine the structures of 1,3-dimethyl-5-formyluracil derivatives with aromatic amines condensation products. The amino-imino prototropic tautomerism occurs at 120°C. It facilitates syn-anti-isomerization promoted cyclization and leads to 1,3-dimethylpyrimido[4,5-b]quinoline-2,4(1H,3H)-dione. The structure of the compounds obtained has been proven using the methods of NMR 1 Н, 13C-spectroscopy, mass-spectra and elemental analysis.
