Agnieszka Chylewska | University of Gdansk (original) (raw)
Papers by Agnieszka Chylewska
Inorganic Chemistry, Jan 3, 2024
Journal of Molecular Liquids, Oct 1, 2017
Abstract Two coordination compounds and their structural characterization of [Ni(PM) 2 ]Cl 2 and ... more Abstract Two coordination compounds and their structural characterization of [Ni(PM) 2 ]Cl 2 and [Ni(PL) 2 ]Cl 2 have been studied. Pyridoxamine (PM) and pyridoxal (PL) denote individual vitamers of vitamin B 6 and both demonstrated bidentate nature inside the complexes. The acid-base behavior of the mentioned complexes and their possible interactions with biomolecules in solutions have been never reported. Here, UV-spectroscopic, potentiometric, cyclic voltammetric studies have been carried out on the interaction of the Ni(II)-vitamer complexes with protons as well as with calf thymus -DNA (CT-DNA) in aqueous medium. The acidity constants values of coordination compounds studied have been determined and compared. The potentiometric and pHmetric-spectrophotometric microtitrations were carried out at the same conditions of temperature and pH range, 25 °C and 1.72–11.68, respectively. The procedural decomposition temperatures of the complexes were given and considered in relation to the structures of the examined compounds to complete the structural description of [Ni(PM) 2 ]Cl 2 and [Ni(PL) 2 ]Cl 2 . The CT-DNA binding potential of Ni(II) complexes was carried out by absorption spectroscopy and cyclic voltammetry methods. Mechanism investigation has demonstrated that examined compounds could interact to CT-DNA by grooving binding mode, which was stabilized by hydrogen bond and van der Waals forces.
Journal of Molecular Liquids, Dec 1, 2019
The detailed studies concerning the binding mode of bioactive ligands: pyrazine-2-carboxamide (PZ... more The detailed studies concerning the binding mode of bioactive ligands: pyrazine-2-carboxamide (PZA), pyrazine-2-thiocarboxamide (PTCA) and pyrazine-2-amidoxime (PAOX) have been performed by using three independent techniques: UVeVis spectroscopy, potentiometry and conductometry. The composition and stability constants of new series Ir(III) complexes with antituberculosis drug and its structural analogues have been determined in aqueous and nonaqueous solutions. The hypsochromic shifts of bands and appearance of new peaks during UVeVis spectrophotometric titration confirmed the interaction of Ir(III) ion with bioligands. In the studied pH range activation of pyrazine derivatives began complexation process. The sharply changed of conductimetric curves slope clearly demonstrated that the ML 2 type complexes formation with relatively high stability are favored. Under the experimental conditions, it was found that metal ion interact with ligands leading to the formation of positively charged complexes. The gradual and cumulative stability constants of Ir(III) coordination compounds have been determined. The stability order of Ir(III)e PY systems studied is as follows: PAOX > PZA > PTCA. The analysis of formation equilibria revealed that mononuclear Ir(III) coordination compounds with metal to ligand molar ratio equals 1:2 are preferable with prominently high solution stability. Comparison of stability constants values showed that an increase in the efficiency of the reaction between metal ion and bioligands was observed with elongation of substituent chain. In the binary complexes, the bidentate nature of bioactive ligands and participation of amine and heterocyclic nitrogens in coordination of central ion were confirmed.
Journal of Physical Organic Chemistry, Feb 4, 2016
The results of the first structural studies (with the use of both experimental and theoretical me... more The results of the first structural studies (with the use of both experimental and theoretical methods) on pyrazine-2amidoxime (PAOX) were shown and discussed. FT-IR spectra were recorded in different concentrations of the PAOX in apolar solvent to check the possibility of the inter-or intramolecular hydrogen-bond formation. All possible tautomers-rotamers of PAOX were then theoretically considered at the DFT(B3LYP)/6-311+G** level in vacuo. For selected isomers, calculations were also performed at higher levels of theory {B3LYP/6-311+G(3df,2p) and G3B3}. Based on the results of DFT calculations, the most stable isomers were found, and their total free energies and infrared spectra were calculated. The energy variation plots for the N8-C7¼N9-O10 and N1¼C2-C7¼N9 dihedral angles were also computed to find two energy barriers, one for E/Z isomerization around the C7¼N9 double bond and the other one for rotation of the pyrazinyl ring around the C2-C7 single bond. The results show that the stability of the PAOX isomers strongly depend on their configuration and orientation of the substituents. The possibilities of inter-and intramolecular hydrogen bonds were also experimentally and theoretically checked. Finally, a potential of mean force was determined in CHCl 3 for a dimer of PAOX with hexamethylphosphoramide. Both, experimental and theoretical results are in agreement.
Current Medicinal Chemistry, May 7, 2018
RSC Advances, 2020
The design of drug structures that are non-toxic, easily transported and permeable to cellular ba... more The design of drug structures that are non-toxic, easily transported and permeable to cellular barriers is currently one of the most growing research trends. Indeed, the structural similarity of 2hydrazinopyrazine (2HP) to pyrazinamide, which has been successfully used in anti-tuberculosis therapy, makes 2HP a promising research object. Thus, herein, a complete analysis of the structure of 2HP and its physicochemical and cytotoxic properties was performed. Calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) binding studies were conducted, which demonstrated the higher affinity of 2HP to BSA. Furthermore, cytotoxicity tests were performed, which proved that 2HP was non-toxic to human skin keratinocyte cells. Accordingly, 2HP was initially classified as a compound with potential application. Physicochemical investigations were performed using a wide range of experiments, which were supported by DFT calculations using the B3LYP functional and 6-311+G** basis set. The good correlation, high quality and correctness of the obtained parameters were proven although the data was obtained using independent techniques. Additionally, 42 tautomeric (prototrophic) forms of 2HP were found by searching the conformational hyperspace. The most energy stable 2HP conformer structure and the partial charge distribution were established. The preferred 2HP ionic forms preferred were presented, and models of the equilibrium occurring in aqueous solution were proposed. The hydrophilic character of 2HP was established based on the partition coefficient values determined by both experiment and theory. The PCM and SMD solvent models of water and n-octanol were used.
Electrochimica Acta, Oct 1, 2021
Abstract The pyrazine-2-thiocarboxamide (PTCA) as a pyrazine derivative with proven antifungal pr... more Abstract The pyrazine-2-thiocarboxamide (PTCA) as a pyrazine derivative with proven antifungal properties has for the first time been the subject of extensive research to evaluate its physicochemistry and ability to interact with biomolecules. The complete physicochemical and electrochemical profile of the studied compound together with its ionic species assignment were established as well as reported. The electrochemical characteristic of PTCA was examined in both: aqueous and aprotic solvent using the cyclic voltammetry technique. All the experimental results obtained were supported and compared with the DFT calculations. Furthermore, the pH effect on the redox processes and PTCA spectroscopic properties were also studied. The pKa values of the compound were determined using combined potentiometric and spectrophotometric/voltammetric (micro)titration methods. The detailed analyses of the PTCA's affinity to Calf thymus DNA and to Bovine Serum Albumin considered in scientific assay as potential cellular targets were the most important parts of the presented study. Indeed, a possible intercalation interaction mode was demonstrated for PTCA-DNA system studied by both spectrophotometric and electrochemical data which has never been reported before. Interestingly, values received by using the broad spectrum of techniques with different, individual measurable parameters have been showed a good agreement compared.
![Research paper thumbnail of Metal-Ion Interactions with Dodecapeptide Fragments of Human Cationic Antimicrobial Protein LL-37 [hCAP(134–170)]](https://attachments.academia-assets.com/116030892/thumbnails/1.jpg)
](The Journal of Physical Chemistry B
Isothermal titration calorimetry, circular dichroism (CD) techniques, and in silico analysis were... more Isothermal titration calorimetry, circular dichroism (CD) techniques, and in silico analysis were used to determine potential metal binding sites in human cationic antimicrobial protein (hCAP) corresponding to overlapping the dodecapeptide sequences of hCAP(134−170) referred to as LL-37. The correct antibacterial action of LL-37 is closely related to its established unique structure. Disturbances in the LL-37 structure (e.g., unwanted presence of metal ions) lead to a radical change in its biological functions. Five fragments of the LL-37 [hCAP(134−170)], namely, hCAP(134−145) (A1), hCAP(140−151) (A2), hCAP(146−157) (A3), hCAP(152−163) (A4), and hCAP(159−170) (A5), were taken into account and their affinity to Mn(II) and Zn(II) ions was rigorously assessed. We prove that only three of the investigated peptides (A1, A2, and A5) are capable of forming thermodynamically stable complexes with metal ions. Additionally, based on density functional theory (DFT) calculations, we propose the most likely coordination modes of metal(II) to peptides as well as discuss the chemical nature of the interactions. Finally, we present the structural features of the strongest binding peptide, hCAP(159−170), responsible for the metal binding. The presented results provide important structural and thermodynamic information to understand the influence of some metal ions on the activity of hCAP(134−170).
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Frontiers in Microbiology, Jul 18, 2018
Although many antifungal agents are available in clinical treatment, increasing resistance of fun... more Although many antifungal agents are available in clinical treatment, increasing resistance of fungi, especially Candida species, to the available drugs requires the development of new safe and non-toxic compounds with novel modes of action as effective treatment against resistant microorganisms. Cobalt complexes are very interesting and attractive as potential candidates with antimicrobial activity. Their therapeutic uses as antiviral, antibacterial antifungal, antiparasitic, antitumour, transferrin transporters, and anti-inflammatory agents are being intensively investigated. In this study we examined the antifungal activity of Co(III) complexes with diamine chelate ligands against a broad spectrum of Candida species. Minimum inhibitory concentration was determined by the microbroth dilution method and with serial passaging assay; the synergistic antimicrobial activity of the tested complexes combined with two antifungal drugs (ketoconazole and amphotericin B) was made by checkerboard assay. The effects of Co(III) complexes on yeast cell morphology were studied by optical and transmission electron microscopy. The mode of action of Co(III) complexes on the yeast cell wall (sorbitol assay) and cell membrane (ergosterol assay) were investigated. The cytotoxic effects of the tested compounds on red blood cells and the human keratinocyte (HaCaT) cell line were also evaluated. The analyzed compounds revealed significant antifungal activity for selected strains of Candida species; [CoCl 2 (dap) 2 ]Cl (1) and [CoCl 2 (en) 2 ]Cl (2) were more effective than ketoconazole. Its probable mechanism of action did not involve the cell wall or ergosterol binding. However, the checkerboard assay showed, that the antifungal activity of ketoconazole increased in combination with the tested complexes of Co(III). Our results suggest that both diamine complexes with Co(III) analogs caused damage to mitochondrial membrane or the membrane of the endoplasmic reticulum. The effect was observed by transmission electron microscope. Co(III) complexes with diamine chelate ligands are non-toxic at concentrations active against Candida species. This study provides new data on potential antifungal drugs, especially against Candida species.
Journal of Molecular Liquids, Feb 1, 2019
Drug-like properties and complete physicochemical profile of pyrazine'2'amidoxime: A combined mul... more Drug-like properties and complete physicochemical profile of pyrazine'2'amidoxime: A combined multi-experimental and computational studies. Molliq (2018),
Chemosensors, Jan 7, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Polyhedron, Nov 1, 2021
Abstract Based on the two anomeric methyl 3-amino-2,3-dideoxy- d -arabino-hexopyranosides ten new... more Abstract Based on the two anomeric methyl 3-amino-2,3-dideoxy- d -arabino-hexopyranosides ten new sugar-modified Schiff base ligands have been synthesized after monocondensation reaction with five o-hydroxyaromatic aldehydes, i.e. salicylaldehyde and its five para-substituted derivatives. The acidity constants and acid-base equilibria processes in polar solution were calculated from data obtained after spectrophotometric titrations at room temperature. The first acidity constant is found to be associated with the deprotonation of an enamine nitrogen and the second constant correspond to the deprotonation of the phenolate oxygen. The contribution of the enol-imine and keto-enamine tautomeric forms and prototropic 1,5-rearrangement has been discussed with the help of the spectroscopic IR, UV-Vis and NMR techniques. Finally, in situ generated catalysts were carried out by mixing separately all synthesized sugar-based Schiff bases with VO(acac)2 or MoO2(acac)2, and have been tested in asymmetric sulfoxidation of thioanisole and the epoxidation of styrene, cyclohexene and S(-)-limonene using tert-butyl hydroperoxide (TBHP) as the terminal oxidant.
Transition Metal Chemistry, Feb 1, 2006
The kinetics of the reaction between gaseous CO2 and the cis-[Cr(phen)2(OH2)2]3+ ion leading to t... more The kinetics of the reaction between gaseous CO2 and the cis-[Cr(phen)2(OH2)2]3+ ion leading to the formation of the carbonato complex ion, have been studied over the pH and temperature ranges: 3 &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; pH &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 6 and 5 T m (NaClO4). Investigations were carried out using the stopped-flow spectrophotometry technique in the UV–Vis range: 340–700 nm. The major reactant species in the
Chemosensors, 2022
Treatment with pyrazine derivatives—antituberculosis pyrazinamide (PZA), anticancer bortezomib (B... more Treatment with pyrazine derivatives—antituberculosis pyrazinamide (PZA), anticancer bortezomib (BZM), and antifungal pyrazine-2-amidoxime (PAOX) and pyrazine-2-thiocarboxamide (PTCA)—is associated with side effects, as observed in the case of other therapeutic drugs. To prevent the side effects of pyrazine derivatives, researchers are working to develop a universal method that will detect these compounds in body fluids. There is a lack of literature data about voltammetric measurements with poly-L-amino acid-modified GCEs surfaces. The available reports describe the application of various modifications of these electrodes for the detection of different active substances of drugs; however, they do not indicate one particular method for the detection of drugs with a pyrazine skeleton. This research aimed to prepare three types of glassy carbon electrodes (GCEs) with modified surfaces by electropolymerization using 1, 10, and 100 mM solutions of L-glycine (Gly), L-alanine (Ala), L-lysi...
Transition Metal Chemistry, 2006
The kinetics of the reaction between gaseous CO2 and the cis-[Cr(phen)2(OH2)2]3+ ion leading to t... more The kinetics of the reaction between gaseous CO2 and the cis-[Cr(phen)2(OH2)2]3+ ion leading to the formation of the carbonato complex ion, have been studied over the pH and temperature ranges: 3 &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; pH &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 6 and 5 T m (NaClO4). Investigations were carried out using the stopped-flow spectrophotometry technique in the UV–Vis range: 340–700 nm. The major reactant species in the
Transition Metal Chemistry, 2006
A stopped-flow method was used to investigate the kinetics of the acid hydrolysis of a newly synt... more A stopped-flow method was used to investigate the kinetics of the acid hydrolysis of a newly synthesised coordination ion of the cis-[Cr(C2O4)(AaraNH2)(O2CO)]− type, where AaraNH2 stands for methyl 3-amino-2,3-dideoxy-α -d-arabino-hexapyranoside, over a range of hydrogen ion concentrations 0.01 +] M and temperatures 5 T 4), the hydrolysis (decarboxylation) of the chromium(III) ion complexed with a bicoordinately linked carbonate ligand turned
Biochemical and Biophysical Research Communications, 2005
For the first time, a direct sensitive method of Å NO 2 detection and measurement in biological m... more For the first time, a direct sensitive method of Å NO 2 detection and measurement in biological material has been established. It is based on the interaction of this radical with the coordination compound of Cr(III) with aminodeoxysugar as biosensor. Our new method makes it possible to precisely assess Å NO 2 level in experimental acute necrotizing pancreatitis induced by L L-arginine, where oxidative and nitrosative stresses are supposed to play a key role in the pathomechanism of the disease. As much as 20 nmol of Å NO 2 /mg protein was detected which correlated with severe deterioration of pancreatic acinar cell ultrastructure. Protective effect of superoxide radical scavenger 4-OH-TEMPO expressed as Å NO 2 level decrease confirmed by preserved acinar cell ultrastructure and decreased pancreatic amylase release to blood serum is demonstrated. This study reveals a possible pathomechanism of L L-arginine induced acute pancreatitis.
Analytical Biochemistry, 2006
This study demonstrated the direct formation of the nitrogen dioxide (Å NO 2) radical during the ... more This study demonstrated the direct formation of the nitrogen dioxide (Å NO 2) radical during the decomposition of 3-morpholinosydnonimine (SIN-1) in biological buffer 4-morpholinoethanosulfone acid solution. Consequently, at approximately pH 4, SIN-1 can be used successfully as a source of Å NO 2. This conclusion is drawn from a comparison of the reactions of cis-[Cr(C 2 O 4)(L-L)(OH 2) 2 ] + , where L-L denotes pyridoxamine (Hpm) or histamine (hm), with the gaseous Å NO 2 radical obtained by two methods: from SIN-1 and from a simple redox reaction. These reactions were investigated using the stopped-flow technique. The measurements were carried out at temperatures ranging from 5 to 25°C over a pH range from 6.52 to 9.11 for cis-[Cr(C 2 O 4)(Hpm) (OH 2) 2 ] + and from 6.03 to 8.15 for cis-[Cr(C 2 O 4)(hm)(OH 2) 2 ] +. We also determined the thermodynamic activation parameter (E a) and the uptake mechanism for each of the coordination compounds studied.
Transition Metal Chemistry, 2006
The cis-[Cr(phen)2(O2CO)]+ ion was prepared through the displacement of two molecules of water fr... more The cis-[Cr(phen)2(O2CO)]+ ion was prepared through the displacement of two molecules of water from the cis-[Cr(phen)2(OH2)2]3+ by the bidentate carbonate anion. It underwent two-phase hydrolysis reactions under acidic conditions (0.1 +] m) at 5, 10, 15, 20 and 25 °C. Via slow carbonato chelate ring opening (first step k1slow) and a second fast decarboxylation(k2fast value). The first step was preceded by
Inorganic Chemistry, Jan 3, 2024
Journal of Molecular Liquids, Oct 1, 2017
Abstract Two coordination compounds and their structural characterization of [Ni(PM) 2 ]Cl 2 and ... more Abstract Two coordination compounds and their structural characterization of [Ni(PM) 2 ]Cl 2 and [Ni(PL) 2 ]Cl 2 have been studied. Pyridoxamine (PM) and pyridoxal (PL) denote individual vitamers of vitamin B 6 and both demonstrated bidentate nature inside the complexes. The acid-base behavior of the mentioned complexes and their possible interactions with biomolecules in solutions have been never reported. Here, UV-spectroscopic, potentiometric, cyclic voltammetric studies have been carried out on the interaction of the Ni(II)-vitamer complexes with protons as well as with calf thymus -DNA (CT-DNA) in aqueous medium. The acidity constants values of coordination compounds studied have been determined and compared. The potentiometric and pHmetric-spectrophotometric microtitrations were carried out at the same conditions of temperature and pH range, 25 °C and 1.72–11.68, respectively. The procedural decomposition temperatures of the complexes were given and considered in relation to the structures of the examined compounds to complete the structural description of [Ni(PM) 2 ]Cl 2 and [Ni(PL) 2 ]Cl 2 . The CT-DNA binding potential of Ni(II) complexes was carried out by absorption spectroscopy and cyclic voltammetry methods. Mechanism investigation has demonstrated that examined compounds could interact to CT-DNA by grooving binding mode, which was stabilized by hydrogen bond and van der Waals forces.
Journal of Molecular Liquids, Dec 1, 2019
The detailed studies concerning the binding mode of bioactive ligands: pyrazine-2-carboxamide (PZ... more The detailed studies concerning the binding mode of bioactive ligands: pyrazine-2-carboxamide (PZA), pyrazine-2-thiocarboxamide (PTCA) and pyrazine-2-amidoxime (PAOX) have been performed by using three independent techniques: UVeVis spectroscopy, potentiometry and conductometry. The composition and stability constants of new series Ir(III) complexes with antituberculosis drug and its structural analogues have been determined in aqueous and nonaqueous solutions. The hypsochromic shifts of bands and appearance of new peaks during UVeVis spectrophotometric titration confirmed the interaction of Ir(III) ion with bioligands. In the studied pH range activation of pyrazine derivatives began complexation process. The sharply changed of conductimetric curves slope clearly demonstrated that the ML 2 type complexes formation with relatively high stability are favored. Under the experimental conditions, it was found that metal ion interact with ligands leading to the formation of positively charged complexes. The gradual and cumulative stability constants of Ir(III) coordination compounds have been determined. The stability order of Ir(III)e PY systems studied is as follows: PAOX > PZA > PTCA. The analysis of formation equilibria revealed that mononuclear Ir(III) coordination compounds with metal to ligand molar ratio equals 1:2 are preferable with prominently high solution stability. Comparison of stability constants values showed that an increase in the efficiency of the reaction between metal ion and bioligands was observed with elongation of substituent chain. In the binary complexes, the bidentate nature of bioactive ligands and participation of amine and heterocyclic nitrogens in coordination of central ion were confirmed.
Journal of Physical Organic Chemistry, Feb 4, 2016
The results of the first structural studies (with the use of both experimental and theoretical me... more The results of the first structural studies (with the use of both experimental and theoretical methods) on pyrazine-2amidoxime (PAOX) were shown and discussed. FT-IR spectra were recorded in different concentrations of the PAOX in apolar solvent to check the possibility of the inter-or intramolecular hydrogen-bond formation. All possible tautomers-rotamers of PAOX were then theoretically considered at the DFT(B3LYP)/6-311+G** level in vacuo. For selected isomers, calculations were also performed at higher levels of theory {B3LYP/6-311+G(3df,2p) and G3B3}. Based on the results of DFT calculations, the most stable isomers were found, and their total free energies and infrared spectra were calculated. The energy variation plots for the N8-C7¼N9-O10 and N1¼C2-C7¼N9 dihedral angles were also computed to find two energy barriers, one for E/Z isomerization around the C7¼N9 double bond and the other one for rotation of the pyrazinyl ring around the C2-C7 single bond. The results show that the stability of the PAOX isomers strongly depend on their configuration and orientation of the substituents. The possibilities of inter-and intramolecular hydrogen bonds were also experimentally and theoretically checked. Finally, a potential of mean force was determined in CHCl 3 for a dimer of PAOX with hexamethylphosphoramide. Both, experimental and theoretical results are in agreement.
Current Medicinal Chemistry, May 7, 2018
RSC Advances, 2020
The design of drug structures that are non-toxic, easily transported and permeable to cellular ba... more The design of drug structures that are non-toxic, easily transported and permeable to cellular barriers is currently one of the most growing research trends. Indeed, the structural similarity of 2hydrazinopyrazine (2HP) to pyrazinamide, which has been successfully used in anti-tuberculosis therapy, makes 2HP a promising research object. Thus, herein, a complete analysis of the structure of 2HP and its physicochemical and cytotoxic properties was performed. Calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) binding studies were conducted, which demonstrated the higher affinity of 2HP to BSA. Furthermore, cytotoxicity tests were performed, which proved that 2HP was non-toxic to human skin keratinocyte cells. Accordingly, 2HP was initially classified as a compound with potential application. Physicochemical investigations were performed using a wide range of experiments, which were supported by DFT calculations using the B3LYP functional and 6-311+G** basis set. The good correlation, high quality and correctness of the obtained parameters were proven although the data was obtained using independent techniques. Additionally, 42 tautomeric (prototrophic) forms of 2HP were found by searching the conformational hyperspace. The most energy stable 2HP conformer structure and the partial charge distribution were established. The preferred 2HP ionic forms preferred were presented, and models of the equilibrium occurring in aqueous solution were proposed. The hydrophilic character of 2HP was established based on the partition coefficient values determined by both experiment and theory. The PCM and SMD solvent models of water and n-octanol were used.
Electrochimica Acta, Oct 1, 2021
Abstract The pyrazine-2-thiocarboxamide (PTCA) as a pyrazine derivative with proven antifungal pr... more Abstract The pyrazine-2-thiocarboxamide (PTCA) as a pyrazine derivative with proven antifungal properties has for the first time been the subject of extensive research to evaluate its physicochemistry and ability to interact with biomolecules. The complete physicochemical and electrochemical profile of the studied compound together with its ionic species assignment were established as well as reported. The electrochemical characteristic of PTCA was examined in both: aqueous and aprotic solvent using the cyclic voltammetry technique. All the experimental results obtained were supported and compared with the DFT calculations. Furthermore, the pH effect on the redox processes and PTCA spectroscopic properties were also studied. The pKa values of the compound were determined using combined potentiometric and spectrophotometric/voltammetric (micro)titration methods. The detailed analyses of the PTCA's affinity to Calf thymus DNA and to Bovine Serum Albumin considered in scientific assay as potential cellular targets were the most important parts of the presented study. Indeed, a possible intercalation interaction mode was demonstrated for PTCA-DNA system studied by both spectrophotometric and electrochemical data which has never been reported before. Interestingly, values received by using the broad spectrum of techniques with different, individual measurable parameters have been showed a good agreement compared.
The Journal of Physical Chemistry B
Isothermal titration calorimetry, circular dichroism (CD) techniques, and in silico analysis were... more Isothermal titration calorimetry, circular dichroism (CD) techniques, and in silico analysis were used to determine potential metal binding sites in human cationic antimicrobial protein (hCAP) corresponding to overlapping the dodecapeptide sequences of hCAP(134−170) referred to as LL-37. The correct antibacterial action of LL-37 is closely related to its established unique structure. Disturbances in the LL-37 structure (e.g., unwanted presence of metal ions) lead to a radical change in its biological functions. Five fragments of the LL-37 [hCAP(134−170)], namely, hCAP(134−145) (A1), hCAP(140−151) (A2), hCAP(146−157) (A3), hCAP(152−163) (A4), and hCAP(159−170) (A5), were taken into account and their affinity to Mn(II) and Zn(II) ions was rigorously assessed. We prove that only three of the investigated peptides (A1, A2, and A5) are capable of forming thermodynamically stable complexes with metal ions. Additionally, based on density functional theory (DFT) calculations, we propose the most likely coordination modes of metal(II) to peptides as well as discuss the chemical nature of the interactions. Finally, we present the structural features of the strongest binding peptide, hCAP(159−170), responsible for the metal binding. The presented results provide important structural and thermodynamic information to understand the influence of some metal ions on the activity of hCAP(134−170).
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Frontiers in Microbiology, Jul 18, 2018
Although many antifungal agents are available in clinical treatment, increasing resistance of fun... more Although many antifungal agents are available in clinical treatment, increasing resistance of fungi, especially Candida species, to the available drugs requires the development of new safe and non-toxic compounds with novel modes of action as effective treatment against resistant microorganisms. Cobalt complexes are very interesting and attractive as potential candidates with antimicrobial activity. Their therapeutic uses as antiviral, antibacterial antifungal, antiparasitic, antitumour, transferrin transporters, and anti-inflammatory agents are being intensively investigated. In this study we examined the antifungal activity of Co(III) complexes with diamine chelate ligands against a broad spectrum of Candida species. Minimum inhibitory concentration was determined by the microbroth dilution method and with serial passaging assay; the synergistic antimicrobial activity of the tested complexes combined with two antifungal drugs (ketoconazole and amphotericin B) was made by checkerboard assay. The effects of Co(III) complexes on yeast cell morphology were studied by optical and transmission electron microscopy. The mode of action of Co(III) complexes on the yeast cell wall (sorbitol assay) and cell membrane (ergosterol assay) were investigated. The cytotoxic effects of the tested compounds on red blood cells and the human keratinocyte (HaCaT) cell line were also evaluated. The analyzed compounds revealed significant antifungal activity for selected strains of Candida species; [CoCl 2 (dap) 2 ]Cl (1) and [CoCl 2 (en) 2 ]Cl (2) were more effective than ketoconazole. Its probable mechanism of action did not involve the cell wall or ergosterol binding. However, the checkerboard assay showed, that the antifungal activity of ketoconazole increased in combination with the tested complexes of Co(III). Our results suggest that both diamine complexes with Co(III) analogs caused damage to mitochondrial membrane or the membrane of the endoplasmic reticulum. The effect was observed by transmission electron microscope. Co(III) complexes with diamine chelate ligands are non-toxic at concentrations active against Candida species. This study provides new data on potential antifungal drugs, especially against Candida species.
Journal of Molecular Liquids, Feb 1, 2019
Drug-like properties and complete physicochemical profile of pyrazine'2'amidoxime: A combined mul... more Drug-like properties and complete physicochemical profile of pyrazine'2'amidoxime: A combined multi-experimental and computational studies. Molliq (2018),
Chemosensors, Jan 7, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Polyhedron, Nov 1, 2021
Abstract Based on the two anomeric methyl 3-amino-2,3-dideoxy- d -arabino-hexopyranosides ten new... more Abstract Based on the two anomeric methyl 3-amino-2,3-dideoxy- d -arabino-hexopyranosides ten new sugar-modified Schiff base ligands have been synthesized after monocondensation reaction with five o-hydroxyaromatic aldehydes, i.e. salicylaldehyde and its five para-substituted derivatives. The acidity constants and acid-base equilibria processes in polar solution were calculated from data obtained after spectrophotometric titrations at room temperature. The first acidity constant is found to be associated with the deprotonation of an enamine nitrogen and the second constant correspond to the deprotonation of the phenolate oxygen. The contribution of the enol-imine and keto-enamine tautomeric forms and prototropic 1,5-rearrangement has been discussed with the help of the spectroscopic IR, UV-Vis and NMR techniques. Finally, in situ generated catalysts were carried out by mixing separately all synthesized sugar-based Schiff bases with VO(acac)2 or MoO2(acac)2, and have been tested in asymmetric sulfoxidation of thioanisole and the epoxidation of styrene, cyclohexene and S(-)-limonene using tert-butyl hydroperoxide (TBHP) as the terminal oxidant.
Transition Metal Chemistry, Feb 1, 2006
The kinetics of the reaction between gaseous CO2 and the cis-[Cr(phen)2(OH2)2]3+ ion leading to t... more The kinetics of the reaction between gaseous CO2 and the cis-[Cr(phen)2(OH2)2]3+ ion leading to the formation of the carbonato complex ion, have been studied over the pH and temperature ranges: 3 &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; pH &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 6 and 5 T m (NaClO4). Investigations were carried out using the stopped-flow spectrophotometry technique in the UV–Vis range: 340–700 nm. The major reactant species in the
Chemosensors, 2022
Treatment with pyrazine derivatives—antituberculosis pyrazinamide (PZA), anticancer bortezomib (B... more Treatment with pyrazine derivatives—antituberculosis pyrazinamide (PZA), anticancer bortezomib (BZM), and antifungal pyrazine-2-amidoxime (PAOX) and pyrazine-2-thiocarboxamide (PTCA)—is associated with side effects, as observed in the case of other therapeutic drugs. To prevent the side effects of pyrazine derivatives, researchers are working to develop a universal method that will detect these compounds in body fluids. There is a lack of literature data about voltammetric measurements with poly-L-amino acid-modified GCEs surfaces. The available reports describe the application of various modifications of these electrodes for the detection of different active substances of drugs; however, they do not indicate one particular method for the detection of drugs with a pyrazine skeleton. This research aimed to prepare three types of glassy carbon electrodes (GCEs) with modified surfaces by electropolymerization using 1, 10, and 100 mM solutions of L-glycine (Gly), L-alanine (Ala), L-lysi...
Transition Metal Chemistry, 2006
The kinetics of the reaction between gaseous CO2 and the cis-[Cr(phen)2(OH2)2]3+ ion leading to t... more The kinetics of the reaction between gaseous CO2 and the cis-[Cr(phen)2(OH2)2]3+ ion leading to the formation of the carbonato complex ion, have been studied over the pH and temperature ranges: 3 &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; pH &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 6 and 5 T m (NaClO4). Investigations were carried out using the stopped-flow spectrophotometry technique in the UV–Vis range: 340–700 nm. The major reactant species in the
Transition Metal Chemistry, 2006
A stopped-flow method was used to investigate the kinetics of the acid hydrolysis of a newly synt... more A stopped-flow method was used to investigate the kinetics of the acid hydrolysis of a newly synthesised coordination ion of the cis-[Cr(C2O4)(AaraNH2)(O2CO)]− type, where AaraNH2 stands for methyl 3-amino-2,3-dideoxy-α -d-arabino-hexapyranoside, over a range of hydrogen ion concentrations 0.01 +] M and temperatures 5 T 4), the hydrolysis (decarboxylation) of the chromium(III) ion complexed with a bicoordinately linked carbonate ligand turned
Biochemical and Biophysical Research Communications, 2005
For the first time, a direct sensitive method of Å NO 2 detection and measurement in biological m... more For the first time, a direct sensitive method of Å NO 2 detection and measurement in biological material has been established. It is based on the interaction of this radical with the coordination compound of Cr(III) with aminodeoxysugar as biosensor. Our new method makes it possible to precisely assess Å NO 2 level in experimental acute necrotizing pancreatitis induced by L L-arginine, where oxidative and nitrosative stresses are supposed to play a key role in the pathomechanism of the disease. As much as 20 nmol of Å NO 2 /mg protein was detected which correlated with severe deterioration of pancreatic acinar cell ultrastructure. Protective effect of superoxide radical scavenger 4-OH-TEMPO expressed as Å NO 2 level decrease confirmed by preserved acinar cell ultrastructure and decreased pancreatic amylase release to blood serum is demonstrated. This study reveals a possible pathomechanism of L L-arginine induced acute pancreatitis.
Analytical Biochemistry, 2006
This study demonstrated the direct formation of the nitrogen dioxide (Å NO 2) radical during the ... more This study demonstrated the direct formation of the nitrogen dioxide (Å NO 2) radical during the decomposition of 3-morpholinosydnonimine (SIN-1) in biological buffer 4-morpholinoethanosulfone acid solution. Consequently, at approximately pH 4, SIN-1 can be used successfully as a source of Å NO 2. This conclusion is drawn from a comparison of the reactions of cis-[Cr(C 2 O 4)(L-L)(OH 2) 2 ] + , where L-L denotes pyridoxamine (Hpm) or histamine (hm), with the gaseous Å NO 2 radical obtained by two methods: from SIN-1 and from a simple redox reaction. These reactions were investigated using the stopped-flow technique. The measurements were carried out at temperatures ranging from 5 to 25°C over a pH range from 6.52 to 9.11 for cis-[Cr(C 2 O 4)(Hpm) (OH 2) 2 ] + and from 6.03 to 8.15 for cis-[Cr(C 2 O 4)(hm)(OH 2) 2 ] +. We also determined the thermodynamic activation parameter (E a) and the uptake mechanism for each of the coordination compounds studied.
Transition Metal Chemistry, 2006
The cis-[Cr(phen)2(O2CO)]+ ion was prepared through the displacement of two molecules of water fr... more The cis-[Cr(phen)2(O2CO)]+ ion was prepared through the displacement of two molecules of water from the cis-[Cr(phen)2(OH2)2]3+ by the bidentate carbonate anion. It underwent two-phase hydrolysis reactions under acidic conditions (0.1 +] m) at 5, 10, 15, 20 and 25 °C. Via slow carbonato chelate ring opening (first step k1slow) and a second fast decarboxylation(k2fast value). The first step was preceded by