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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 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.
3
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.
4
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.
5
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.
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