Małgorzata Sztanke

An insight into synthetic Schiff bases revealing antiproliferative activities in vitro

Schiff bases or azomethines are among the most important groups of biomolecules. These compounds have been found to reveal both remarkable biological activities and a variety of valuable practical applications. An interest in the exploration of novel series of synthetic Schiff bases has undoubtedly been growing due to their proven utility as attractive lead structures for the design of novel cytotoxic and cytostatic agents with a mechanism of action that sometimes differs from that of clinically authorized anticancer agents. Therefore, in the present paper we have focussed our attention on the collected synthetic simple Schiff bases of aldimine- and ketimine-types revealing anticancer activities in vitro, that have been described in the scientific literature during the last decade, and on structural variations whose affect the antiproliferative activity in sets of the designed molecules.

Volatile Anesthetics Reduce Biochemical Markers of Brain Injury and Brain Magnesium Disorders in Patients Undergoing Coronary Artery Bypass Graft Surgery

OBJECTIVES Neuropsychological disorders are some of the most common complications of coronary artery bypass graft (CABG) surgery. The early diagnosis of postoperative brain damage is difficult and mainly based on the observation of specific brain injury markers. The aim of this study was to analyze the effects of volatile anesthesia (VA) on plasma total and ionized arteriovenous magnesium concentrations in the brain circulation (a-vtMg and a-viMg), plasma matrix metalloproteinase-9 (MMP-9), and glial fibrillary acidic protein (GFAP) in adult patients undergoing CABG surgery. DESIGN An observational study. SETTING The Department of Cardiac Surgery in a Medical University Hospital. PATIENTS AND METHODS Studied parameters were measured during surgery and in the early postoperative period. Patients were assigned to 3 groups: group O, patients who did not receive VA; group ISO, patients who received isoflurane; and group SEV, patients who received sevoflurane. RESULTS Ninety-two patients were examined. CABG surgery increased MMP-9 and GFAP. The highest MMP-9, GFAP, and the most dramatic disorders in a-vtMg and a-viMg were noted in group O. CONCLUSIONS Cardiac surgery increased plasma MMP-9 and GFAP concentrations. Changes in MMP-9, GFAP, and arteriovenous tMg and iMg were significantly higher in group O. Volatile anesthetics, such as ISO or SEV, reduced plasma MMP-9, GFAP concentrations, and disturbances in a-vtMg and a-viMg.

Crystal structure, antitumour and antimetastatic activities of disubstituted fused 1,2,4-triazinones

Molecular structure of 3,8-disubstituted 7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-ones (8-14) was confirmed by X-ray crystallography of 14. All the compounds were evaluated for their antitumour and antimetastatic activities in vitro. Furthermore, their cytotoxicities towards human normal cell line-HSF cells were established, allowing us to point out some structure-activity relationships. Among them, imidazotriazinone 12, revealing remarkable dose-dependent viability decreases in human myeloma RPMI 8226 cells, was found to be completely non-toxic towards normal HSF cells. In addition, heterobicycles 8-12 were proved to exhibit significant antimetastatic potentials in the motility assay.

Reversed-phase liquid chromatography with octadecylsilyl, immobilized artificial membrane and cholesterol columns in correlation studies with in silico biological descriptors of newly synthesized antiproliferative and analgesic active compounds

Reversed-phase liquid chromatography (RPLC) with different stationary phases, i.e., octadecylsilyl, immobilized artificial membrane and immobilized cholesterol, was used to study lipophilicity of 56 newly-designed 7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-ones and 2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-diones with potential anti-proliferative, anti-metastatic and analgesic activities. Extrapolated retention parameters that correspond to pure buffer as the mobile phase, i.e., logkw values are used as chromatographic lipophilicities. The lipophilic properties of compounds also are characterized by computed logP values and basic pharmacokinetic descriptors calculated in silico with the use of ACD/Percepta software according to Abrahams linear solvation energy relationship. Chromatographic and partitioning parameters are compared with biological descriptors using principal component analysis (PCA), and similarities and dissimilarities between variables and compounds are described. Highly significant, predictive relationships between biological descriptors and chromatographic parameters are obtained. Reversed parabolic relationships, which have very good statistical quality between various biological descriptors, i.e., logKsc, logKp, logBB, and logKhsa, and the logkw values, indicate the advantages of a cholesterol column in comparison with immobilized artificial membrane and octadecylsilyl stationary phase.

Synthesis, structure elucidation, determination of the lipophilicity and identification of antitumour activities in vitro of novel 3-(2-furanyl)-8-aryl-7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-ones with a low cytotoxicity towards normal human skin fibroblast cells

Eleven novel 3-(2-furanyl)-8-aryl-7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-ones (12-22) were designed and obtained from appropriate 1-aryl-2-hydrazonoimidazolidines (1-11) by condensation reaction with 2-oxo-2-furanacetic acid and subsequent cyclocondensation of intermediate chain derivatives. IR, (1)H NMR and (13)C NMR spectra and elemental analyses confirmed the chemical structure of all the synthesized compounds. The reversed-phase HPLC method was optimized and proved to be applicable and reliable for the analysis of these unknown small molecules (12-22). These compounds were chromatographed on octadecyl silica (ODS) stationary phase and their hydrophobic parameters expressed as the log k(w) values were determined by RP-HPLC, using mixtures of methanol and water as mobile phases with different methanol concentrations. Octane-1-sulfonic acid sodium salt (OSA-Na) and 20% acetate buffer (pH 3.5) was added to the mobile phase (eluent containing 0.01 M/L OSA-Na in organic modifier (MeOH)-buffered mobile phase). The high values of regression coefficients (r >0.9841) for all the compounds investigated proved the excellent fit between experimental data and the Snyder-Soczewiński equation. Results obtained from the reversed-phase HPLC were compared both with those theoretically calculated and with those obtained from an ALOGPS 2.1. software by the use of nine different computational methods for estimation of log P. The predicted values of log P by use of AB log P algorithm revealed the best correlation with the experimental log k(w) values for the investigated solutes, since a good correlation (r=0.7760) between these quantities was found. The majority of novel imidazotriazinones were found to be evidently effective in vitro against human cancerous cells (HeLa and T47D) in an effective concentration of 50 μg/mL. Five compounds (13, 15, 16, 18 and 22) revealed remarkable antiproliferative activities and selective cytotoxicities for cancer cells over normal HSF cells. Therefore these ones may be considered as a basis for the design of novel useful non-toxic (13, 15 and 16) and low toxic (18 and 22) anticancer agents.

Synthesis, structure elucidation and identification of antiproliferative activities of a novel class of thiophene bioisosteres bearing the privileged 7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-one scaffold.

The straightforward and practical synthesis route and remarkable antitumour activities in vitro of a novel class of thiophene bioisosteres (10-18) are disclosed. These molecules were obtained with good overall yields via the reaction of 1-aryl-2-hydrazonoimidazolidine hydroiodides with ethyl 2-oxo-2-(2-thienyl)acetate in the presence of triethylamine in refluxing DMF/methanol mixture. All the synthesized compounds proved to be markedly effective against human tumour cells: A549, HeLa, T47D and TOV112D and more cytotoxic than pemetrexed against A549, HeLa and T47D cells. Among these strongly antiproliferative active molecules, the disclosed three thiophene bioisosteres (11, 17 and 18) are proposed as the most promising anticancer lead structures for the rational design of more selective antitumour agents because they proved to be markedly lower cytotoxic towards normal than tumour cells. Results from the bioassay based on a double fluorochrome staining were worthy to be described because they provide a clue to the mode of action of one (18) of the most promising anticancer lead structures of the series.

Synthesis, structure elucidation and in vitro anticancer activities of novel derivatives of diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinate and ethyl (4-oxo-8-aryl-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl)acetate

The worked out and optimized synthesis routes and remarkable antitumour activities in vitro of novel polynitrogenated derivatives of diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinate (7-10) and ethyl (4-oxo-8-aryl-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl)acetate (11-16) are presented. Small molecules based on the privileged 7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-one scaffold (11-16) were obtained with fairly modest to good overall yields by very facile addition reactions of the nucleophilic centred 1-aryl-2-hydrazonoimidazolidine hydroiodides to diethyl acetylenedicarboxylate (DEAD) in the presence of triethylamine (TEA) and a subsequent cyclocondensation of the putative intermediate chain hydrazones. Heterobicyclic products 12 and 14-16 could also be prepared in high overall yields by an effective intramolecular cyclocondensation of the isolated stable and antiproliferative active heterocyclic hydrazones, namely, diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinates (7-10), performed in refluxing DMF. These intermediates are the first products to be formed in the result of an addition of the nucleophilic reactants, namely, 1-aryl-2-hydrazonoimidazolidines of the 1-6 type, bearing the basic nitrogen atom of the hydrazono moiety (N-NH2), to the carbon-carbon triple bond of the highly electrophilic alkyne, that is, DEAD. Molecular structures of the synthesized compounds (7-16) in the DMSO-d6 solutions were verified by (1)H NMR and (13)C NMR spectral data. These were finally confirmed based on the advanced 2D HMBC and HMQC NMR experiments, which were performed for the two representatives (8 and 11) of the two synthesized sets of the bioactive substances. Among the majority of antiproliferative active molecules, the disclosed herein ethyl [4-oxo-8-(3-chlorophenyl)-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetate (14) is proposed as a promising lead structure for the design of novel highly selective antitumour agents because of the distinctly marked lower cytotoxicity towards the primary cell line of normal HSF cells and several-fold higher against cancer cells used. A double fluorochrome mix-staining was performed in order to find out about the possible mode of action by which this novel small heterobicycle reveals remarkable antiproliferative effects in vitro. Taking into account the obtained double staining results, this small molecule was identified as capable of inducing significantly higher levels of necrotic cells in human cancer cell lines (T47D and HeLa) than in normal HSF cells. Furthermore, its cytotoxicity against cells was found to be connected to the predominant induction of necrosis over apoptosis.

Plasma matrix metalloproteinase 9 correlates with disorders of brain magnesium homeostasis in patients undergoing coronary artery bypass surgery

BACKGROUND Changes in plasma matrix metalloproteinase 9 (MMP-9) concentrations and parallel changes in brain magnesium homeostasis have not been examined in cardiac surgery patients. The purpose of the present study was to analyse these relationships in patients undergoing coronary artery bypass surgery (CABG) with extracorporeal circulation (ECC). Additionally, the effect of volatile anaesthetics was considered. PATIENTS AND METHODS Adult patients undergoing CABG with ECC under general anaesthesia were studied. Plasma MMP-9 and total (tMg) and ionized (iMg) magnesium concentrations were measured during surgery and during the early postoperative period. The plasma arteriovenous (a-v) tMg and iMg differences in the brain circulation were considered to be markers for brain magnesium homeostasis. The Mini-Mental State Examination test and computer tomography were used to diagnose postoperative neuropsychological disorders (PNPDs). RESULTS In total, 92 patients were examined. PNPDs were noted in 17 cases. Cardiac surgery resulted in increased plasma levels of MMP-9. The highest MMP-9 concentrations were observed in patients with PNPDs. MMP-9 concentrations strongly correlated with a-v tMg and a-v iMg differences. Compared with arterial measurements, venous tMg and iMg concentrations were higher during and immediately after surgery and lower during the early postoperative period. The most severe differences in a-v tMg and iMg were noted in patients with PNPDs. CONCLUSION 1. Cardiac surgery resulted in an increase in plasma MMP-9 concentrations. 2. This increase in MMP-9 was significantly greater in patients with PNPDs. 3. The plasma MMP-9 concentration was correlated with disorders of brain Mg homeostasis.

Structure–retention behaviour of biologically active fused 1,2,4-triazinones – Correlation with in silico molecular properties

The chromatographic behaviour and significant lipophilicity/hydrophobicity indices (log k(w), S, φ(0)) are presented for 21 biologically active fused 1,2,4-triazinones based on the linear relationship: log k = log k(w)-Sφ established for the retention on LC-18 HPLC column, using as mobile phases mixtures of three organic modifiers with water. The effect of these mobile phase modifiers on the chromatographic behaviour of solutes was established and the organic modifier of choice is suggested. The complex correlation of slopes versus intercepts obtained for acetonitrile, contrary to linear ones obtained for methanol and dioxane are disclosed. The observed difference in retention mechanism for acetonitrile compared to methanol and dioxane is explained by intermolecular interactions encoded in lipophilicity. Linear correlations with statistically significant levels between log kw values determined from three different chromatographic systems were obtained. The relationships between log k(w) constants (derived from the linear model for methanol-water mobile phases) and predicted log P and log S values by the use of various computational methods were investigated and these were established with high correlation coefficients. The predicted log P values plotted against φ(0 (MeOH)) indices showed the best fit. Principal component analysis was used to compare various lipophilicity parameters of the solutes and their in silico biological descriptors relevant to optimal pharmacokinetics profile. The similarities and dissimilarities between all the variables and molecular structures of solutes are presented. Statistically significant correlations were found between the chromatographic lipophilicity indices and the calculated pharmacokinetic descriptors: fraction unbound in brain (f(u, brain)), oral bioavailability (%F), permeability and intestinal absorption in jejunum (Caco-2), skin permeation (log K(p)) and blood/brain concentration (log BB).

Biologically important hydrazide-containing fused azaisocytosines as antioxidant agents

ABSTRACT Objectives: Two important classes of hydrazide-containing fused azaisocytosines were evaluated as possible antioxidants and characterised by UV spectroscopy. Methods: 2,2-Diphenyl-1-picrylhydazyl (DPPH), nitric oxide (NO), hydrogen peroxide (H2O2) scavenging potencies and reducing power of molecules were evaluated. Results: The strongest DPPH scavengers were found to be 9, showing the potency superior to that of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) and comparable to that of ascorbic acid (AA), and 6, revealing the antioxidant potency superior to that of BHA, BHT, PG and Trolox. In turn, 3 and 9 were the most promising NO scavengers, exhibiting the potency superior to that of BHA, BHT (3 and 9) and AA (3). The most potent H2O2 scavengers proved to be 10 and 9 showing similar or even better neutralising potency than that of Trolox, BHT and BHA. Simultaneously, the majority of hydrazides revealed higher ferric reducing abilities than that of AA and BHT. Some structure-activity relationships were explored. A possible mechanism for the DPPH radical scavenging ability of hydrazide-containing molecules was proposed. Discussion: Hydrazides 3, 6 and 9 with an antioxidant potential better or comparable to that of the well-known antioxidants are proposed as new antioxidant candidates.