Vol. 17 No. 3(67) (2019)
Published:
2019-09-05
Original Researches
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The search for potential inhibitors of protein kinase Pim-1 among new amides of 1,2,4-triazolo[4,3-a]pyridine-3-metanamin with the 1,2,4-oxadiazol cycle in position 7 and 8
The Pim-1 enzyme from the serine/threonine protein kinase family is a likely target for the targeted therapy of tumors of hematopoietic and lymphoid tissues. Triazolopyridine is an universal scaffold upon which international scientific programs have been launched to develop potential anticancer agents.
Aim. To create a pharmacophore model to find new potential Pim-1 inhibitors; conduct a virtual screening of a simulated base of new 1,2,4-triazolo[4,3-a]pyridine derivatives; develop a method for the synthesis of 1,2,4-triazolo[4,3-a]pyridine-3-methanamines with the 1,2,4-isoxadiazole cycle.
Results and discussion. In this study, a ligand-based pharmacophore model for Pim-1 inhibitors was constructed and validated. A virtual screening of the library with 912 compounds resulted in a hit list of 175 compounds. For the synthesis, 15 compounds were selected with the highest pharmacophore-fit score. 15 compounds were synthesized as potential inhibitors of Pim-1 kinase.
Experimental part. The synthetic approach has been developed, and systematic series of new amides of (7-(1,2,4-oxadiazol-5-yl)-[1,2,4]triazolo[4,3-a]pyridin-3-yl)methanamine and (8-(1,2,4-oxadiazol-5-yl)-[1,2,4]triazolo[4,3-a]pyridin-3-yl)methanamine have been synthesized.
Conclusions. The compounds obtained are potential inhibitors of Pim-1 kinase. Further studies will focus on the determination of the antitumor activity of the compounds synthesized by in vitro and in vivo methods. -
Synthesis and antioxidant properties of novel thiazolo[4,5-b]pyridine-2-ones
Aim. To expand the synthetic potential of thiazolo[4,5-b]pyridines, study the reactivity and perform the pharmacological screening of the antioxidant activity of the novel compounds synthesized.
Results and discussion. A series of novel 3-aryl-5-hydroxy-7-methyl-3H-thiazolo[4,5-b]pyridine-2-ones were obtained as a result of the interaction of 3-aryl-4-iminothiazolidine-2-ones with ethyl acetoacetate. At this stage the resulting 3-phenyl-5-hydroxy-7-methyl-3H-thiazolo[4,5-b]pyridin-2-one was modified in position 5 in the acylation reaction. For all compounds synthesized the primary pharmacological screening of the antioxidant activity was performed; the results showed the potential for the search of antioxidant agents among thiazolo[4,5-b]pyridine-2-ones.
Experimental part. By the reactions of [3+3]-cyclocondensation and acylation 12 novel thiazolo[4,5-b]pyridine-2-ones were obtained. The structure of all compounds synthesized was confirmed by the method of 1H NMR-spectroscopy and the data of elemental analysis. The antioxidant activity of the compounds synthesized was investigated in vitro by the method of scavenging effect on 2,2-diphenyl-1-picrylhydrazyl radical.
Conclusions. 12 novel thiazolo[4,5-b]pyridines have been synthesized, their antioxidant properties have been investigated, and prospectivity for the search of novel antioxidant agents among thiazolo[4,5-b]pyridines has been shown. -
Synthesis and the biological activity of bis-mefenamidocalixarene
Aim. To develop the method for the synthesis of the conjugate of diaminocalix[4]arene with 2-(2,3-dimethylphenyl)aminobenzoic acid (mefenamic acid) – bis-mefenamidocalixarene, determine its structure and physicochemical properties and assess its anti-exudative activity (AeA).
Results and discussion. The conjugate of diaminocalixarene with mefenamic acid – bis-mefenamidocalixarene was synthesized at one step by the reaction of reactants in equimolar amounts in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The structure of the compound obtained was determined by spectral methods. AeA of bis-mefenamidocalixarene was studied in rats using the model of formalin edema. The results of the experimental studies showed that bis-mefenamidocalixarene exhibited the anti-exudative activity, which was equal to the reference drug – sodium diclofenac.
Experimental part. The reaction of diaminocalixaren with 2- (2,3-dimethylphenyl)aminobenzoic acid (mefenamic acid) led to bis-mefenamidocalixarene with 40 % yield. The screening of AeA was carried out using modern digital plethysmometer (IITC Life Science (USA)).
Conclusions. The effective one-stage method for the synthesis of the conjugate of diaminocalix[4]arene with 2-(2,3-dimethylphenyl)aminobenzoic acid – bis-mefenamidocalixarene has been developed. Its structure has been proven, and AeA has been studied. AeA is equal to the reference drug. It has been found that bis-mefenamidokalixaren synthesized is a promising compound for further profound studies. -
The study of the antimicrobial activity of the derivatives of 6-(1,2,4-oxadizol-3-yl)- and 6-(2-aminothiazol-4-yl)thieno[2,3-d]pyrimidin-4-ones by the double dilution method
Aim. To study profoundly the antimicrobial activity of the derivatives of 6-(1,2,4-oxadizol-3-yl)- and 6-(2-aminothiazol-4-yl)thieno[2,3-d]pyrimidin-4-ones by the double dilution method.
Results and discussion. For the derivatives of 6-heterylthieno[2,3-d]pyrimidines, namely the derivatives of 6-(1,2,4-oxadizol-3-yl)- and 6-(2-aminothiazol-4-yl)thieno[2,3-d]pyrimidin-4-ones selected after the prescreening by the agar well diffusion method, the further antimicrobial activity study using the double dilution method was performed. The minimal bacteriostatic and bactericidal concentrations were determined.
Experimental part. The synthesis of the target molecules was performed according to the methods previously developed. The antimicrobial activity was studied using the double-dilution method.
Conclusions. The derivatives of 5-methyl-6-(3-aryl-1,2,4-oxadizol-5-yl)thieno[2,3-d]pyrimidin-4(3H)-one with the free position 3 of the thieno[2,3-d]pyrimidine system showed the highest bactericidal activity in the concentration of 125 μg/mL against the test-strains of S. aureus, E. coli and B. subtilis. -
The acid-base properties of 2-(benzoylamino)(1-R-2-oxoindolin-3-ylidene)acetic acids
Aim. To study the acid-base properties of derivatives of 2-(benzoylamino)(1-R-2-oxoindolin-3-ylidene)acetic acid substituted by the location 1 of oxoindolin fragment.
Results and discussion. The compounds studied are weak acids, their strength decreases with the elongation of the alkyl fragment in a heterocyclic nitrogen atom due to the extinction of the inductive effect. The reaction center (carboxyl group) has low sensitivity to the influence of substituents, and it may be due to the location distance of the substituents, as well as disturbance of coplanarity between the reaction center and the bicyclic fragment of the molecule. The ionization constants of a series of 2-(benzoylamino)(1-R-2-oxoindolin-3-ylidene)acetic acids have been set; the compounds studied are weak acids, their strength regularly decreases with replacement of the hydrogen atom at the heterocyclic nitrogen atom with methyl fragment, while the elongation of the alkyl fragment has little effect on their dissociation. The dependence of the ionization process on the nature of the substituents according to the Hammeth equation is quantified and it is shown that the reaction center (carboxyl group) has a small sensitivity to the influence of the substituents, which can be related both to the distance of the substituents location and to the violation of the coplanarity between the reaction center and the bicyclic fragment of the molecule. The small value of the ionization constant is consistent with the data of the (2Z)-(benzoylamino)(1-methyl-2-oxoindolin-3-ylidene)acetic acid stereostructure.
Experimental part. The acid-base properties of 2-(benzoylamino)(2-oxoindolin-3-ylidene)acetic acid derivatives was studied by the method of potentiometric titration on an EV-74 ionomer with a glass indicator electrode (ESP 43-074) and a saturated silver chloride (EVP-1) reference electrode at 298 К within three analytical runs. A mixture of 1,4-dioxane–water (60:40, v/v) was used as a solvent. The structure of the molecule of (2Z)-(benzoylamino)(1-methyl-2-oxoindolin-3-ylidene)acetic acid was determined by X-ray diffraction analysis.
Conclusions. The reactivity of the series of 2-(benzoylamino)(1-R-2-oxoindolin-3-ylidene)acetic acid has been investigated by studying the acid-base equilibria. Their ionization constants have been determined and the influence of alkyl radicals at the heterocycle nitrogen atom on the acid-base properties has been analyzed; the low sensitivity of the reaction center to the influence of substituents has been proved. The correlation equation pKa – f(σ) obtained has reliable statistical characteristics and can be used for QSAR analysis of active pharmacophores of this isostructural series. -
Development and validation of the enzymatic kinetic photometric procedure for determination of residual quantities of dequalinium chloride on the surface of the pharmaceutical equipment
Aim. To develop and validate the new enzymatic kinetic photometric procedure for analysis of dequalinium chloride based on application of enzymatic acetylcholine hydrolysis to determine the residual quantities of dequalinium chloride while monitoring the completeness of cleaning of the pharmaceutical equipment.
Results and discussion. The optimal conditions for the enzymatic reaction course were determined – the order of mixing and the concentration of acetylcholine (0.05 mg/mL), cholinesterase (0.4 mg/mL), hydrogen peroxide (10 %) and p-phenetedine (1 %), the time of the reaction mixture maintaining (20 min), pH (8.35), the effect of the nature of the buffer solution. Validation of the procedure developed was carried out – the application range of the procedure was proposed (40–160 % in the normalized coordinates, the maximum acceptable concentration of dequalinium chloride in washes from the pharmaceutical equipment хcrit = 0.5 μg/mL), the number of concentration levels (n = 7); the order of their location within the application range, taking these data into account the maximum acceptable uncertainty of the procedure (maxΔx = 3.05 %) and the acceptability criteria for linear dependence parameters, systematic and random errors were calculated. The validation characteristics of the procedure developed were shown to correspond to the acceptability criteria calculated. The degree of extraction of dequalinium chloride from swabs with flushing from the pharmaceutical equipment was determined.
Experimental part. The residual quantities of dequalinium chloride on the surface of the pharmaceutical equipment were determined by the degree of inhibition of the enzymatic reaction assessed by the unreacted residue of the substrate of the biochemical reaction, such as acetylcholine. The residual quantities of acetylcholine in the reaction mixture was determined by the kinetic photometric method by the indicator reaction of p-phenetidine oxidation with peracetic acid (formed during the auxiliary perhydrolysis reaction when adding an excess of hydrogen peroxide to the reaction mixture) in the way of registering the light absorbance of the resulting reaction product – azoxifenetole (λmax = 358 nm) for a definite period of time.
Conclusions. The enzymatic kinetic photometric procedure has been developed to determine the residual quantities of dequalinium chloride on the surface of the pharmaceutical equipment after its cleaning. The procedure developed has been validated by such parameters as linearity, accuracy, precision and the limit of quantification -
The comparative quantum chemical study of the epoxidation reaction mechanism of eugenol and isoeugenol with peracetic and perbenzoic acids
Aim. To study the kinetics of the epoxidation reaction for eugenol and isoeugenol with perbenzoic acid, carry out the comparative quantum chemical study of the epoxidation reaction mechanism of eugenol and isoeugenol isomers (2-cis and 2-trans) with peracetic and perbenzoic acids.
Results and discussion. The kinetics of the epoxidation reaction of isomeric terpenoids eugenol and isoeugenol with perbenzoic acid in the medium of methylene chloride medium at 293 K was studied using the method of iodometric titration. It was shown that the rate constant of the epoxidation reaction for eugenol was in 5.5 times higher than for isoeugenol. According to the results of quantum chemical calculations using the UBH&HLYP/6-31G (d) approximation, the structures of transition states of eugenol and isoeugenol formed during the epoxidation reactions studied were proposed, and the activation energies for the corresponding reactions were calculated. Based on the results of the studies conducted it was found that the ratio of the activation energies during the interaction of eugenol and isoeugenol with peracetic and perbenzoic acids showed the higher reactivity of isoeugenol.
Experimental part. To study the kinetics of the epoxidation reaction the method of iodometric titration was used. The method of the functional density (software Gaussian 09, approximation UBH&HLYP/6-31G (d)) was applied for calculation.
Conclusions. The results of the quantum chemical study of the epoxidation reaction mechanism of eugenol and isoeugenol are consistent with the kinetic data experimentally obtained; it confirms the correctness of using the UBH&HLYP/6-31G (d) approximation for studying the features of epoxidation of isomeric terpenoids with organic peracids. -
Development and validation of the HPLC-procedure for the quantitative determination of isosorbide dinitrate in matrix granules
Isosorbide dinitrate is a universally recognized drug for the relief of angina attacks. Today, prolonged forms of isosorbide dinitrate are of great interest due to their high antianginal efficacy and lower frequency of side effects that are characteristic for drugs with immediate release.
Aim. To develop the procedure for the quantitative determination of isosorbide dinitrate in matrix granules using high performance liquid chromatography and validate it.
Results. To determine isosorbide dinitrate by the method of high performance liquid chromatography with UV-detection the optimal chromatographic conditions were selected taking into account the effect of excipients in the composition of the medicine. To prove the possibility of applying the procedure proposed in the further analysis of matrix granules of isosorbide dinitrate its validation was carried out. Such validation parameters as specificity, linearity, repeatability, accuracy, intermediate precision, limit of detection and limit of quantification, robustness were assessed using model solutions.
Experimental part. The chromatographic researches were performed using liquid chromatograph Shimadzu LC-20AD XR with diode-array detector under the following conditions: chromatographic column – Supelco Discovery C18 (150 × 4.6 мм, 5 мкм); mobile phase – water R – buffer solution with (pH 4.7) – methanol R2 (35:10:55); elution mode – isocratic; flow rate of the mobile phase – 1.0 mL/min.; detection wavelength –220 nm; software – LCsolution, 1.24.SP.1 version.
Conclusions. A new procedure for the quantitative determination of isosorbide dinitrate in matrix granules has been developed using high performance liquid chromatography. Its validation has been carried out, and its acceptability has been proven.
