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ABSTRACT: The aim of this study is to encapsulate two drugs: 5-fluorouracil (5-FU) with the hydrophobic properties and 1-β-D-arabinofuranosylcytosine
(Ara-C) with the amphiphilic properties into liposomes prepared by the modified reverse-phase evaporation method (mREV) from
L-α-phosphatidylcholine dipalmitoyl (DPPC). We studied the thermotropic phase behavior of liposome entrapped 5-FU and Ara-C.
It is known that the stability of liposomes depends not only on the method of chemical gradient loading, the use of membrane
stabilizer such as sterols, but also on the phase transition temperature (T
c) of phospholipids, which undergoes an alteration after encapsulation of drugs to liposomes. The competition of these two
drugs entrapped in liposomes was analyzed by the use of two spectroscopies: 1H NMR and UV on the basis of the analysis of the signals of each drug in the liposome—drug system. The percent of encapsulation
in DPPC/Ara-C/5-FU liposome obtained by the use of UV spectroscopy amounted 93.84 and 96.05% for 5-FU and Ara-C, respectively.
Phase transition temperature T
c of liposomes containing Ara-C did not significantly change while for the liposomes containing 5-FU it increased in comparison
with T
c of the reference liposomes formed from DPPC.
KeywordsLiposome–Multidrug therapy–mREV–NMR–UV
Journal of Thermal Analysis and Calorimetry 04/2012; 108(1):67-71. · 1.60 Impact Factor
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ABSTRACT: The aim of this work was to encapsulate two drugs: 5-Fluorouracil (5-FU) with the hydrophobic properties and 5-Formyl-5,6,7,8-tetrahydropteroyl-L-glutamic acid calcium salt (leucovorin) with the hydrophilic properties into liposomes prepared by the modified reverse-phase evaporation method (mREV) from L-α-phosphatidylcholine dipalmitoyl (DPPC). The drugs are used in the anticancer multidrug therapy FLv (5-fluorouracil, leucovorin) and ELF (etoposide, leucovorin, 5-fluorouracil). We studied the competition for their encapsulation in liposomes by the use of two spectroscopies: 1H NMR and UV on the basis of the analysis of the signals of each drug in the liposome – drug system. Liposomes are highly versatile structures for research, therapeutic and analytical applications. We concluded that the liposomes obtained by the mREV method may transport more than one drug simultaneously.
Molecular Crystals and Liquid Crystals 12/2010; 523(1):282/[854]-288/[860]. · 0.58 Impact Factor
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ABSTRACT: In this study waste polystyrene foam and virgin polystyrene as a reference materials were converted by chemical reactions under heterogeneous conditions into useful products. Polymeric flocculants were obtained from polystyrene during the sulfonation with sulfuric acid as the sulfonating agent and Ag2SO4 as the catalyst. The influence of temperature and time of reaction on the properties of the products were studied. The products were successfully used as flocculants in the treatment of the waste water. Solid silica sulfuric acid was also used to convert polystyrene. In comparison with the conventional sulfonation methods this sulfonating agent simplifies the reaction and makes easier separation of products from acid and solvent. The obtained products were cross-linked and exhibited cation-exchange properties. The batch method was used to study purification of solutions of Zn2+ and Cu2+ by the yielded resins. The performed study proved the usefulness of waste polystyrene derivatives for water treatment process.
Molecular Crystals and Liquid Crystals. 12/2010; 523(1):218/[790]-227/[799].
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ABSTRACT: The aim of the investigation was the dynamic thermo-mechanical analysis (DMTA) study of the polyurethane-rubber composites obtained from used polymer products. Polyols obtained in the glycolysis process from used semi-rigid polyurethane foams, hardened by diphenylmethane 4,4′-diisocyanate (MDI) and rubber granules obtained from mechanical granulation of used car tyres were used to receive polyurethane-rubber composites. On the basis of the DMTA spectra the glass transition temperature Tg was determined. The analysis of loss module E′′ allowed us to observe two relaxation processes for polyurethane-waste rubber composites α – originating from the rubber and α′ – from the polyurethane glue. The dependence of the changes of activation energy of relaxation processes with the change of weight ratio of polyurethane glue in polyurethane-waste rubber composites was observed.
Molecular Crystals and Liquid Crystals. 12/2010; 523(1):173/[745]-181/[753].
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ABSTRACT: BSA Binding site Chloro(triethylphosphine)gold(I) 3-MaleimidoPROXYL EPR a b s t r a c t EPR spectroscopy was applied to determine the binding site of chloro(triethylphosphine)gold(I), (ClAu-PEt 3), in bovine serum albumin (BSA). The EPR spectrum of the spin marker covalently bonded to the sul-phydryl group of polypeptide chain shows the presence of two 3-maleimidoPROXYL populations which differ in their way of immobilization. The first population shows the spin marker with a strongly restricted rotation due to hydrogen bonds between the oxygen of the label agent nitroxyl group and hydrogen atoms of the polypeptide chain with possible participation of water. The second population contains the spin marker bound with Cys-34 sulphydryl group located outside the crevice between heli-ces h2 and h3, weakly immobilized by water hydrogen bonds. The addition of ClAuPEt 3 results in the changes of the shape of spin labeled albumin EPR spectra. The displacement of 3-maleimidoPROXYL is observed below ClAuPEt 3 :BSA molar ratio 0.5:1. It is possible that above this molar ratio another bonding of the displaced spin marker takes place, having a high freedom of movement. EPR spectra, recorded after dialysis, show displacement of 3-maleimidoPROXYL molecules and the competition between AuPEt 3 and the spin marker to the mutual binding site with cysteine residue.
Journal of Molecular Structure 03/2010; 970:106-110. · 1.63 Impact Factor
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Molecular Crystals and Liquid Crystals 06/2008; 483(2008: pp. 155–162):155-162. · 0.58 Impact Factor
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ABSTRACT: The mol-ecule of the title compound, C(12)H(16)N(2)O(4), is centrosymmetric and the amide group is twisted relative to the benzene ring by 14.40 (13)°. The mol-ecules are hydrogen bonded into a three-dimensional framework, with the hydr-oxy O atoms acting as acceptors in N-H⋯O hydrogen bonds and as donors in O-H⋯O=C inter-actions.
Acta Crystallographica Section E Structure Reports Online 01/2008; 64(Pt 7):o1277. · 0.35 Impact Factor
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ABSTRACT: The aim of the present work was to compare the concentration changes of polyaromatic hydrocarbons (PAH) and the course of humification processes during wastewater treatment. Studies of samples from a biological-mechanical wastewater treatment plant in Sosnowiec-Zagórze (Poland) were carried out. Determination of PAH was performed both for wastewater sludge and sludge water. Observations of the course of humification processes for humic acid fractions isolated from sludges were conducted. Analysis of PAH extracted from wastewaters and from sludge was performed by means of high-performance liquid chromatography. Investigations of humification processes were conducted by electron paramagnetic resonance and nuclear magnetic resonance methods. The elementary composition changes in the structure of the extracted humic acids were determined. It was found that polyaromatic hydrocarbons appear during the processes of humification. Their content in water decreased only after the process of sludge aeration; however, sludge water leaving the settlers was PAH-enriched.
Water Environment Research 11/2006; 78(11):2186-92. · 0.88 Impact Factor
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ABSTRACT: The aim of this study was to describe a competition between cytarabine (araC) and aspirin (ASA) in binding with bovine serum albumin (BSA). High-affinity binding sites for both drugs were determined using a spectrofluorimetric method. Cytarabine as well as aspirin binds in the IIA hydrophobic subdomain of the transporting protein. Binding constants for araC-BSA and ASA-BSA were calculated by the Scatchard method. Analysis of ultraviolet (UV) difference spectra showed that araC, which has a higher affinity to BSA in comparison to ASA [Ka(araC) > Ka(ASA)] displaces ASA in high-affinity binding sites. The competition between drugs in low-affinity binding sites was investigated using (1)H nuclear magnetic resonance (NMR) and 13C-NMR spectra. We concluded that in the low-affinity binding sites cytarabine decreases the affinity of albumin toward aspirin. However, the interaction between araC and BSA becomes more difficult in the presence of aspirin.
Biopolymers 05/2006; 81(6):464-72. · 2.87 Impact Factor
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ABSTRACT: Pathologic structure of albumin is present in blood of uremic or diabetic patients. The defective binding of albumin can cause, among others, inhibition of the metabolism of amphipathic hormones and the enhancement of the toxicity of drugs.We aim to show the alteration of the binding site of 6-propyl-2-thiouracil (PTU) in bovine serum albumin (BSA) in the presence of urea and guanidine hydrochloride. This study shows that PTU has the tendency to interact within the hydrophobic domain IIA or IB of serum albumin and to quench the fluorescence of tryptophanyl side chains by the static and collisional quenching mechanism.For the binding to the native protein, two classes of binding sites are seen. In the first one, the binding constant is equal to KbI−9.6×104 M−1, and in the second class, the binding constant is KbII−7.1×103 M−1. For the binding to the denaturated serum albumin, only one class of the binding sites can be observed. The binding constants for BSA denatured with urea and Gu·HCl are lower and are equal to 2.2×104 M−1 and 3.5×104 M−1, respectively.Evaluation of the binding ability of serum albumin is also important in case of older people because weaker drug–protein interaction can result in the increase of drug concentration in the blood serum.
Journal of Molecular Structure.
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ABSTRACT: The EPR and NMR spectroscopy was used to determine the structure and physicochemical properties of liposomes prepared from dl-α-phosphatidylcholine dimyristoyl (1,2-ditetradecanoyl-rac-glycerol-3-phosphocholine) (DMPC) by the modified reverse-phase evaporation (mREV). EPR study was carried out in the temperature range from 284 to 310 K, i.e. below and above the phase transition temperature Tc of DMPC. On the basis of EPR spectra of spin marker 2-(carboxypropyl)-4,4-dimethyl-2-tridecyl-3-oxazolidinyloxyl (5-DOXYL) incorporated into liposome, the parameters S (empirical order parameter), 2Amax (line widths) and τ (rotational correlation time) were determined. Temperature and pH dependent structural changes of liposome were also described. 31P NMR study of the liposome in the temperature range from 340 to 350 K allowed to suggest that the single-bilayered liposome were obtained.
Journal of Molecular Structure.
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ABSTRACT: EPR spectroscopy was applied to determine the binding site of chloro(triethylphosphine)gold(I), (ClAuPEt3), in bovine serum albumin (BSA). The EPR spectrum of the spin marker covalently bonded to the sulphydryl group of polypeptide chain shows the presence of two 3-maleimidoPROXYL populations which differ in their way of immobilization. The first population shows the spin marker with a strongly restricted rotation due to hydrogen bonds between the oxygen of the label agent nitroxyl group and hydrogen atoms of the polypeptide chain with possible participation of water. The second population contains the spin marker bound with Cys-34 sulphydryl group located outside the crevice between helices h2 and h3, weakly immobilized by water hydrogen bonds. The addition of ClAuPEt3 results in the changes of the shape of spin labeled albumin EPR spectra. The displacement of 3-maleimidoPROXYL is observed below ClAuPEt3:BSA molar ratio 0.5:1. It is possible that above this molar ratio another bonding of the displaced spin marker takes place, having a high freedom of movement. EPR spectra, recorded after dialysis, show displacement of 3-maleimidoPROXYL molecules and the competition between AuPEt3 and the spin marker to the mutual binding site with cysteine residue.
Journal of Molecular Structure. 970:106-110.
