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1
Content available The influence of displacement compounds on the binding of ochratoxin A to human serum albumin examined with fluorescence anisotropy methods
Wybranowski T, Ziomkowska B., Cwynar A, Kruszewski S.
Optica Applicata
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2014
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Vol. 44, nr 3
357--364
EN
The subject of the research is the application of the methods of fluorescence anisotropy measurements to study the interaction between human serum albumin (HSA) and toxins and selected medicines (ibuprofen, warfarin, flurbiprofen). Optical spectroscopic methods are useful tools for the study of biologically active compounds. Determining binding intensity of ochratoxin A (OTA) to albumin may be helpful in explaining the effects of toxic influence of OTA. The main factor influencing the distribution of OTA is its affinity for plasma proteins. It was shown that ochratoxin binds strongly to albumin. By the use of the method of fluorescence anisotropy it was proved that the unbound fraction of OTA is higher due to competing interactions with drugs. As a result of separating ochratoxin from protein by competitive compounds, a decrease in the fluorescence anisotropy of the HSA-OTA complex was observed. The largest increase in free fraction of OTA is caused by flurbiprofen, then ibuprofen and warfarin. It will accelerate OTA transport to target organs and shortening its half-life period, leading consequently to a decrease in chronic toxic effects.
2
Content available remote Affinity of new anticancer agent, 7-trimethylsilyl-ethyl-10-amino-camptothecin, to membranes and HSA determined by fluorescence spectroscopy methods
Kruszewski S., Kruszewska D. M.
Optica Applicata
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2008
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Vol. 38, nr 4
625-633
EN
The application of fluorescence anisotropy measurements in determining the properties of camptothecin analogue 7-trimethylsilylethyl-10-amino-camptothecin - a promising anticancer agent - is described in this paper. The fluorescence anisotropy measurements provide useful information about binding of camptothecins to membranes and proteins, including human serum albumin (HSA). Knowledge of these properties is important for potential clinical applications of these agents, and permits to select from camptothecin analogues only those which exhibit desirable properties. An active lactone form of camptothecin in fluids at pH 7.4 hydrolyses and converts into an inactive carboxylate form. The carboxylate form of camptothecin binds easily and irreversibly to HSA. Only free carboxylate form can transform back into lactone, then in the presence of HSA one direction transition occurs (from lactone to carboxylate); therefore in HSA solution, after about two hours, the lactone form almost totaly decays. On the other hand, the camptothecins bound to membranes do not hydrolyse. Fluorescence anisotropy measurements prove that 7-trimethylsilylethyl-10-amino-camptothecin exhibits desirable properties: high affinity of its lactone form to membranes and low affinity of its carboxylate form to HSA. Such properties should ensure high stability of this drug in physiological fluids, including blood.
3
Content available remote Membranes affinity of hydroxycamptothecins, anticancer agents, determined by fluorescence spectra analysis
Cyrankiewicz M., Ziomkowska B., Kruszewski S.
Optica Applicata
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2006
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Vol. 36, nr 2-3
209-215
EN
In this paper the method of determination of membranes affinity of hydroxycamptothecins is described. Under physiological conditions hydroxycamptothecins easily hydrolyze and convert into inactive carboxylate form. The process of deactivation is inhibited when the molecules of drug are bound to cell membranes so it is desirable that hydroxycamptothecins molecules bind easily to membranes. A quantitative measure of drugs affinity to membranes is the association constant. To determine this parameter the small unilamellar liposomes are used as model membranes. The affinities of 10-hydroxycamptothecin, SN-38 and DB-67 to membranes are determined. The association constants are calculated on the basis of changes of fluorescence spectra.
4
Content available remote Deactivation rate of camptothecin determined by factor analysis of steady-state fluorescence and absorption spectra
Ziomkowska B., Kruszewski S., Siuda R., Cyrankiewicz M.
Optica Applicata
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2006
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Vol. 36, nr 1
137-146
EN
Camptothecin is a fluorescent compound exhibiting strong anticancer properties. A serious limitation to clinical application of this compound is its hydrolysis, when biologically active lactone form converts into inactive carboxylate. There are some differences in the shapes of both fluorescence and absorption spectra of the lactone and carboxylate forms of camptothecin. Therefore, during hydrolysis resultant fluorescence and absorption spectra evolve. Factor analysis of fluorescence/absorption spectra recorded during the hydrolysis process of camptothecin enables one to determine the temporary concentration of the lactone and carboxylate forms and obtain the deactivation rate of this compound.
5
Content available remote Affinity of new anticancer agent, DB-174, to membranes and HSA determined by fluorescence spectroscopy methods
Kruszewski S., Bom D., Ziomkowska B., Cyrankiewicz M.
Optica Applicata
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2006
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Vol. 36, nr 2-3
199-207
EN
The application of fluorescence spectroscopy methods to determining the properties of camptothecins promising anticancer agents are described in this paper. The fluorescence anisotropy measurements provide useful information about the binding of camptothecin and its analogues to cell membranes and human serum albumin (HSA) that is important for potential clinical applications of these agents, and permits the selection from many camptothecin analogues those ones exhibiting desirable biomedical properties. Binding properties of 7-trimethylsilyl-ethyl-10 hydroxy-camptothecin are the subject of this paper.
6
Content available remote Application of principal component and factor analysis of fluorescence spectra in camptothecin studies
Kruszewski S., Siuda R., Ziomkowska B., Cyrankiewicz M.
Optica Applicata
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2003
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Vol. 33, nr 2-3
369-380
EN
The application of fluorescence spectroscopy methods in investigations of camptothecin (CPT) is presented in this paper. Fluorescence of CPT enables one to follow the process of hydrolysis, i.e., the process of converting the biologically active lactone form into inactive carboxylate. The fluorescence spectra of CPT recorded during the hydrolysis were analysed using principal component analysis (PCA) and factor analysis (FA). The results obtained on the basis of fluorescence spectra analysis are compared with high performance liquid chromatography (HPLC) data.
7
Content available remote Zastosowanie metod fluorometrycznych do określania właściwości kamptotecyny i jej pochodnych
Kruszewski S.
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna
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2003
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Vol. 9, nr 3-4
151-156
PL
Kamptotecyna (CPT) i jej pochodne stanowią ważną klasę S-fazowych przeciwnowotworowych związków. W warunkach fizjologicznych CPT szybko hydrolizuje i przechodzi w nieaktywną formę karboksylową. Zanik biologicznie aktywnej formy CPT jest szczególnie szybki w osoczu krwi. Analog kamptotecyny DB-67, w przeciwieństwie do CPT, wykazuje wyjątkowo dużą stabilność we krwi. Metody spektroskopii fluorescencyjnej zostały zastosowane do określania fizycznych i przewidywania biologicznych właściwości kamptotecyny i jej analogów.
EN
Camptothecin (CPT) and related congeners have became an important class of S-phase anticancer agent. Unfortunately CPT hydrolyses under physiological conditions, and converts into inactive carboxylate form. Decrease of active form of CPT occurs especially fast in plasma of human blood. The new camptothecin analogue DB-67, in contrary to CPT, exhibits impressive blood stability. Fluorescence spectroscopy methods were used to determine physical and to predict biological properties of camptothecins.
8
Content available remote Camptothecins affinity to HSA and membranes determined by fluorescence anisotropy measurements
Kruszewski S., Burke T.G.
Optica Applicata
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2002
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Vol. 32, nr 4
721-730
EN
The application of fluorescence spectroscopy methods in determining the properties of camptothecins – promising anticancer agents – is described in this paper. The fluorescence anisotropy measurements provide useful information about the binding of camptothecins to human serum albumin (HSA) and to cell membranes, which is important for potential clinical applications of these agents, and permits the selection from among many camptothecin analogues those the ones exhibiting desirable biomedical properties.
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