The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
Franciszek K. Główka - One of the best experts on this subject based on the ideXlab platform.
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In Vitro Study of the Enzymatic and Nonenzymatic Conjugation of Treosulfan with Glutathione
European Journal of Drug Metabolism and Pharmacokinetics, 2019Co-Authors: Michał Romański, Franciszek K. GłówkaAbstract:Background and Objectives Treosulfan (dihydroxybusulfan), licensed for the treatment of ovarian carcinoma, is investigated in clinical trials as a Myeloablative Agent for conditioning prior to hematopoietic stem cell transplantation. Clinical experience shows that treosulfan exhibits lower organ toxicity than busulfan, including hepatotoxicity. Elimination of busulfan primarily via enzymatic conjugation with glutathione (GSH) in the liver is considered to be the main cause of the drug’s hepatotoxicity and interpatient clearance variability. It is believed that treosulfan undergoes no hepatic metabolism but empirical evidence is lacking. The aim of this kinetic study was to verify if treosulfan is capable of conjugating with GSH. Methods Treosulfan (200 μM) was incubated at pH 7.2 and 37 °C with 5 mM GSH in the presence or absence of human liver cytosol, the main store of glutathione S -transferase in the body. Concentrations of treosulfan were determined using liquid chromatography–tandem mass spectrometry and then subjected to kinetic analysis. Results The decay of treosulfan in the solution followed a one-exponential model in the presence of either GSH or liver cytosol and GSH. The first-order reaction rate constants (0.25 h^−1) did not differ statistically from those found for treosulfan conversion in pH 7.2 buffer only. Conclusion Treosulfan does not undergo either spontaneous or enzymatic conjugation with GSH at a noticeable rate. The result indicates that the clearance of treosulfan is independent of glutathione S -transferase activity, GSH stores, and co-administration of drugs utilizing the GSH metabolic pathway.
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In Vitro Study of the Enzymatic and Nonenzymatic Conjugation of Treosulfan with Glutathione.
European journal of drug metabolism and pharmacokinetics, 2019Co-Authors: Michał Romański, Franciszek K. GłówkaAbstract:Treosulfan (dihydroxybusulfan), licensed for the treatment of ovarian carcinoma, is investigated in clinical trials as a Myeloablative Agent for conditioning prior to hematopoietic stem cell transplantation. Clinical experience shows that treosulfan exhibits lower organ toxicity than busulfan, including hepatotoxicity. Elimination of busulfan primarily via enzymatic conjugation with glutathione (GSH) in the liver is considered to be the main cause of the drug’s hepatotoxicity and interpatient clearance variability. It is believed that treosulfan undergoes no hepatic metabolism but empirical evidence is lacking. The aim of this kinetic study was to verify if treosulfan is capable of conjugating with GSH. Treosulfan (200 μM) was incubated at pH 7.2 and 37 °C with 5 mM GSH in the presence or absence of human liver cytosol, the main store of glutathione S-transferase in the body. Concentrations of treosulfan were determined using liquid chromatography–tandem mass spectrometry and then subjected to kinetic analysis. The decay of treosulfan in the solution followed a one-exponential model in the presence of either GSH or liver cytosol and GSH. The first-order reaction rate constants (0.25 h−1) did not differ statistically from those found for treosulfan conversion in pH 7.2 buffer only. Treosulfan does not undergo either spontaneous or enzymatic conjugation with GSH at a noticeable rate. The result indicates that the clearance of treosulfan is independent of glutathione S-transferase activity, GSH stores, and co-administration of drugs utilizing the GSH metabolic pathway.
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Relationship between exposure to treosulfan and its monoepoxytransformer - An insight from population pharmacokinetic study in pediatric patients before hematopoietic stem cell transplantation.
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, 2018Co-Authors: Dorota Danielak, Tomasz Wróbel, Anna Kasprzyk, Jacek Wachowiak, Krzysztof Kałwak, Franciszek K. GłówkaAbstract:Abstract Treosulfan (TREO), a structural analog of busulfan, is currently studied as a Myeloablative Agent in conditioning regimens before hematopoietic stem cell transplantation in pediatric patients. High exposure to TREO (>1650 mg∗h/mL) might be related to early toxicity, especially skin toxicity and mucositis. The aim of the present study was to investigate a potential relationship between exposure to TREO and its monoepoxytransformer (S,S-EBDM), as well as variability of the pharmacokinetics of these entities by means of a population pharmacokinetic approach with a non-linear mixed-effects analysis. The study included data from 14 children with malignant and non-malignant diseases treated with TREO in daily doses 10–14 g/m2. The parent-metabolite population pharmacokinetic model was developed in NONMEM 7.3 software. Upon the constructed model, an extensive simulation was performed to assess the correlation between exposure to TREO and S,S-EBDM. It was found that TREO and S,S-EBDM pharmacokinetics was best described with 2-compartmental and 1-compartmental linear models, respectively. The vast majority (>65%) of TREO was transformed to S,S-EBDM. Overall, a considerable interpatient variability of pharmacokinetic parameters was observed, especially the clearance of S,S-EBDM. A weak correlation was found between the exposure to TREO and S,S-EBDM (r = 0.1681, p In summary, a parent-metabolite population pharmacokinetic model for TREO and S,S-EBDM was developed for the first time. It was shown that there is a weak correlation between exposure to TREO and S,S-EBDM. Therefore therapeutic drug monitoring of not only prodrug but also its active epoxide might be needed.
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Formation Rate-Limited Pharmacokinetics of Biologically Active Epoxy Transformers of Prodrug Treosulfan.
Journal of pharmaceutical sciences, 2016Co-Authors: Michał Romański, Anna Kasprzyk, Agnieszka Karbownik, Edyta Szałek, Franciszek K. GłówkaAbstract:Abstract A prodrug treosulfan (TREO) is being evaluated in clinical trials as a Myeloablative Agent before hematopoietic stem cell transplantation. The active derivatives of TREO, monoepoxide (EBDM), and diepoxide (DEB) are formed in a pH-dependent nonenzymatic reaction. The aim of the study was to investigate pharmacokinetics of the TREO epoxy transformers in a rabbit model and explain the causes of low plasma concentrations of EBDM and DEB observed in patients receiving high-dose TREO before hematopoietic stem cell transplantation. New Zealand white rabbits ( n = 5 per cohort) received an intravenous infusion of TREO (group I), injection of DEB (group II), and injection of a solution containing EBDM (group III). When EBDM and DEB were administered to the rabbits, they underwent a very rapid elimination (half-life 0.069 and 0.046 h) associated with a high systemic clearance (10.0 and 14.0 L h −1 kg −1 ). After administration of TREO, the t 1/2 of EBDM was statistically equal to the t 1/2 of the prodrug (1.6 h). To conclude, after administration of TREO, its epoxy transformers demonstrate a formation-limited elimination. Then EBDM and DEB have the same elimination half-life as TREO, but the levels of EBDM and DEB in the body, including plasma, are much lower than TREO on account of their inherently high clearance.
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Direct high-performance liquid chromatography method with refractometric detection designed for stability studies of treosulfan and its biologically active epoxy-transformers.
Analytical Abstracts, 2012Co-Authors: Franciszek K. Główka, Michał Romański, Artur Teżyk, C. ZabaAbstract:Treosulfan (TREO) is an alkylating Agent registered for treatment of advanced platin-resistant ovarian carcinoma. Nowadays, TREO is increasingly applied iv in high doses as a promising Myeloablative Agent with low organ toxicity in children. Under physiological conditions it undergoes pH-dependent transformation into epoxy-transformers (S,S-EBDM and S,S-DEB). The mechanism of this reaction is generally known, but not its kinetic details. In order to investigate kinetics of TREO transformation, HPLC method with refractometric detection for simultaneous determination of the three analytes in one analytical run has been developed for the first time.The samples containing TREO, S,S-EBDM, S,S-DEB and acetaminophen (internal standard) were directly injected onto the reversed phase column. To assure stability of the analytes and obtain their complete resolution, mobile phase composed of acetate buffer pH 4.5 and acetonitrile was applied. The linear range of the calibration curves of TREO, S,S-EBDM and S,S-DEB spanned concentrations of 20-6000, 34-8600 and 50-6000 µM, respectively. Intra- and interday precision and accuracy of the developed method fulfilled analytical criteria. The stability of the analytes in experimental samples was also established. The validated HPLC method was successfully applied to the investigation of the kinetics of TREO activation to S,S-EBDM and S,S-DEB. At pH 7.4 and 37 °C the transformation of TREO followed first-order kinetics with a half-life 1.5 h.
A Sureda - One of the best experts on this subject based on the ideXlab platform.
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Current status and future perspectives for yttrium-90 (^90Y)-ibritumomab tiuxetan in stem cell transplantation for non-Hodgkin's lymphoma
Bone Marrow Transplantation, 2007Co-Authors: C Gisselbrecht, W Bethge, R F Duarte, A M Gianni, B Glass, C Haioun, G Martinelli, A Nagler, R Pettengell, A SuredaAbstract:Haematopoietic SCT is currently considered a therapeutic option mainly in relapsed or refractory non-Hodgkin's lymphoma (NHL) owing to high post-transplantation relapse rates and significant toxicity of conventional Myeloablative conditioning for allogeneic SCT. Radiolabelled immunotherapy combines the benefits of monoclonal antibody targeting with therapeutic doses of radiation, and is a promising advance in the treatment of malignant lymphomas. It is now under investigation as a component of conditioning prior to SCT, with the aim of improving outcomes following SCT without increasing the toxicity of high-dose chemotherapy pre-transplant conditioning. An expert panel met at a European workshop in November 2006 to review the latest data on radiolabelled immunotherapy in the transplant setting, and its potential future directions, with a focus on ^90Y-ibritumomab tiuxetan. They reviewed data on the combination of standard/high/escalating dose ^90Y-ibritumomab tiuxetan with high-dose chemotherapy, and high/escalating dose ^90Y-ibritumomab tiuxetan as the sole Myeloablative Agent, prior to autologous SCT, and also ^90Y-ibritumomab tiuxetan as a component of reduced intensity conditioning prior to allogeneic SCT. The preliminary data are highly promising in terms of conditioning tolerability and patient outcomes following transplant; further phase II studies are now needed to consolidate these data and to investigate specific patient populations and NHL subtypes.
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Current status and future perspectives for yttrium-90 ((90)Y)-ibritumomab tiuxetan in stem cell transplantation for non-Hodgkin's lymphoma
'Springer Science and Business Media LLC', 2007Co-Authors: C Gisselbrecht, W Bethge, R F Duarte, A M Gianni, B Glass, C Haioun, G Martinelli, A Nagler, R Pettengell, A SuredaAbstract:Haematopoietic SCT is currently considered a therapeutic option mainly in relapsed or refractory non-Hodgkin's lymphoma (NHL) owing to high post-transplantation relapse rates and significant toxicity of conventional Myeloablative conditioning for allogeneic SCT. Radiolabelled immunotherapy combines the benefits of monoclonal antibody targeting with therapeutic doses of radiation, and is a promising advance in the treatment of malignant lymphomas. It is now under investigation as a component of conditioning prior to SCT, with the aim of improving outcomes following SCT without increasing the toxicity of high-dose chemotherapy pre-transplant conditioning. An expert panel met at a European workshop in November 2006 to review the latest data on radiolabelled immunotherapy in the transplant setting, and its potential future directions, with a focus on 90Y-ibritumomab tiuxetan. They reviewed data on the combination of standard/high/escalating dose 90Y-ibritumomab tiuxetan with high-dose chemotherapy, and high/escalating dose 90Y-ibritumomab tiuxetan as the sole Myeloablative Agent, prior to autologous SCT, and also 90Y- ibritumomab tiuxetan as a component of reduced intensity conditioning prior to allogeneic SCT. The preliminary data are highly promising in terms of conditioning tolerability and patient outcomes following transplant; further phase II studies are now needed to consolidate these data and to investigate specific patient populations and NHL subtypes
C Gisselbrecht - One of the best experts on this subject based on the ideXlab platform.
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Current status and future perspectives for yttrium-90 (^90Y)-ibritumomab tiuxetan in stem cell transplantation for non-Hodgkin's lymphoma
Bone Marrow Transplantation, 2007Co-Authors: C Gisselbrecht, W Bethge, R F Duarte, A M Gianni, B Glass, C Haioun, G Martinelli, A Nagler, R Pettengell, A SuredaAbstract:Haematopoietic SCT is currently considered a therapeutic option mainly in relapsed or refractory non-Hodgkin's lymphoma (NHL) owing to high post-transplantation relapse rates and significant toxicity of conventional Myeloablative conditioning for allogeneic SCT. Radiolabelled immunotherapy combines the benefits of monoclonal antibody targeting with therapeutic doses of radiation, and is a promising advance in the treatment of malignant lymphomas. It is now under investigation as a component of conditioning prior to SCT, with the aim of improving outcomes following SCT without increasing the toxicity of high-dose chemotherapy pre-transplant conditioning. An expert panel met at a European workshop in November 2006 to review the latest data on radiolabelled immunotherapy in the transplant setting, and its potential future directions, with a focus on ^90Y-ibritumomab tiuxetan. They reviewed data on the combination of standard/high/escalating dose ^90Y-ibritumomab tiuxetan with high-dose chemotherapy, and high/escalating dose ^90Y-ibritumomab tiuxetan as the sole Myeloablative Agent, prior to autologous SCT, and also ^90Y-ibritumomab tiuxetan as a component of reduced intensity conditioning prior to allogeneic SCT. The preliminary data are highly promising in terms of conditioning tolerability and patient outcomes following transplant; further phase II studies are now needed to consolidate these data and to investigate specific patient populations and NHL subtypes.
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Current status and future perspectives for yttrium-90 ((90)Y)-ibritumomab tiuxetan in stem cell transplantation for non-Hodgkin's lymphoma
'Springer Science and Business Media LLC', 2007Co-Authors: C Gisselbrecht, W Bethge, R F Duarte, A M Gianni, B Glass, C Haioun, G Martinelli, A Nagler, R Pettengell, A SuredaAbstract:Haematopoietic SCT is currently considered a therapeutic option mainly in relapsed or refractory non-Hodgkin's lymphoma (NHL) owing to high post-transplantation relapse rates and significant toxicity of conventional Myeloablative conditioning for allogeneic SCT. Radiolabelled immunotherapy combines the benefits of monoclonal antibody targeting with therapeutic doses of radiation, and is a promising advance in the treatment of malignant lymphomas. It is now under investigation as a component of conditioning prior to SCT, with the aim of improving outcomes following SCT without increasing the toxicity of high-dose chemotherapy pre-transplant conditioning. An expert panel met at a European workshop in November 2006 to review the latest data on radiolabelled immunotherapy in the transplant setting, and its potential future directions, with a focus on 90Y-ibritumomab tiuxetan. They reviewed data on the combination of standard/high/escalating dose 90Y-ibritumomab tiuxetan with high-dose chemotherapy, and high/escalating dose 90Y-ibritumomab tiuxetan as the sole Myeloablative Agent, prior to autologous SCT, and also 90Y- ibritumomab tiuxetan as a component of reduced intensity conditioning prior to allogeneic SCT. The preliminary data are highly promising in terms of conditioning tolerability and patient outcomes following transplant; further phase II studies are now needed to consolidate these data and to investigate specific patient populations and NHL subtypes
Michał Romański - One of the best experts on this subject based on the ideXlab platform.
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In Vitro Study of the Enzymatic and Nonenzymatic Conjugation of Treosulfan with Glutathione
European Journal of Drug Metabolism and Pharmacokinetics, 2019Co-Authors: Michał Romański, Franciszek K. GłówkaAbstract:Background and Objectives Treosulfan (dihydroxybusulfan), licensed for the treatment of ovarian carcinoma, is investigated in clinical trials as a Myeloablative Agent for conditioning prior to hematopoietic stem cell transplantation. Clinical experience shows that treosulfan exhibits lower organ toxicity than busulfan, including hepatotoxicity. Elimination of busulfan primarily via enzymatic conjugation with glutathione (GSH) in the liver is considered to be the main cause of the drug’s hepatotoxicity and interpatient clearance variability. It is believed that treosulfan undergoes no hepatic metabolism but empirical evidence is lacking. The aim of this kinetic study was to verify if treosulfan is capable of conjugating with GSH. Methods Treosulfan (200 μM) was incubated at pH 7.2 and 37 °C with 5 mM GSH in the presence or absence of human liver cytosol, the main store of glutathione S -transferase in the body. Concentrations of treosulfan were determined using liquid chromatography–tandem mass spectrometry and then subjected to kinetic analysis. Results The decay of treosulfan in the solution followed a one-exponential model in the presence of either GSH or liver cytosol and GSH. The first-order reaction rate constants (0.25 h^−1) did not differ statistically from those found for treosulfan conversion in pH 7.2 buffer only. Conclusion Treosulfan does not undergo either spontaneous or enzymatic conjugation with GSH at a noticeable rate. The result indicates that the clearance of treosulfan is independent of glutathione S -transferase activity, GSH stores, and co-administration of drugs utilizing the GSH metabolic pathway.
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In Vitro Study of the Enzymatic and Nonenzymatic Conjugation of Treosulfan with Glutathione.
European journal of drug metabolism and pharmacokinetics, 2019Co-Authors: Michał Romański, Franciszek K. GłówkaAbstract:Treosulfan (dihydroxybusulfan), licensed for the treatment of ovarian carcinoma, is investigated in clinical trials as a Myeloablative Agent for conditioning prior to hematopoietic stem cell transplantation. Clinical experience shows that treosulfan exhibits lower organ toxicity than busulfan, including hepatotoxicity. Elimination of busulfan primarily via enzymatic conjugation with glutathione (GSH) in the liver is considered to be the main cause of the drug’s hepatotoxicity and interpatient clearance variability. It is believed that treosulfan undergoes no hepatic metabolism but empirical evidence is lacking. The aim of this kinetic study was to verify if treosulfan is capable of conjugating with GSH. Treosulfan (200 μM) was incubated at pH 7.2 and 37 °C with 5 mM GSH in the presence or absence of human liver cytosol, the main store of glutathione S-transferase in the body. Concentrations of treosulfan were determined using liquid chromatography–tandem mass spectrometry and then subjected to kinetic analysis. The decay of treosulfan in the solution followed a one-exponential model in the presence of either GSH or liver cytosol and GSH. The first-order reaction rate constants (0.25 h−1) did not differ statistically from those found for treosulfan conversion in pH 7.2 buffer only. Treosulfan does not undergo either spontaneous or enzymatic conjugation with GSH at a noticeable rate. The result indicates that the clearance of treosulfan is independent of glutathione S-transferase activity, GSH stores, and co-administration of drugs utilizing the GSH metabolic pathway.
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Formation Rate-Limited Pharmacokinetics of Biologically Active Epoxy Transformers of Prodrug Treosulfan.
Journal of pharmaceutical sciences, 2016Co-Authors: Michał Romański, Anna Kasprzyk, Agnieszka Karbownik, Edyta Szałek, Franciszek K. GłówkaAbstract:Abstract A prodrug treosulfan (TREO) is being evaluated in clinical trials as a Myeloablative Agent before hematopoietic stem cell transplantation. The active derivatives of TREO, monoepoxide (EBDM), and diepoxide (DEB) are formed in a pH-dependent nonenzymatic reaction. The aim of the study was to investigate pharmacokinetics of the TREO epoxy transformers in a rabbit model and explain the causes of low plasma concentrations of EBDM and DEB observed in patients receiving high-dose TREO before hematopoietic stem cell transplantation. New Zealand white rabbits ( n = 5 per cohort) received an intravenous infusion of TREO (group I), injection of DEB (group II), and injection of a solution containing EBDM (group III). When EBDM and DEB were administered to the rabbits, they underwent a very rapid elimination (half-life 0.069 and 0.046 h) associated with a high systemic clearance (10.0 and 14.0 L h −1 kg −1 ). After administration of TREO, the t 1/2 of EBDM was statistically equal to the t 1/2 of the prodrug (1.6 h). To conclude, after administration of TREO, its epoxy transformers demonstrate a formation-limited elimination. Then EBDM and DEB have the same elimination half-life as TREO, but the levels of EBDM and DEB in the body, including plasma, are much lower than TREO on account of their inherently high clearance.
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Direct high-performance liquid chromatography method with refractometric detection designed for stability studies of treosulfan and its biologically active epoxy-transformers.
Analytical Abstracts, 2012Co-Authors: Franciszek K. Główka, Michał Romański, Artur Teżyk, C. ZabaAbstract:Treosulfan (TREO) is an alkylating Agent registered for treatment of advanced platin-resistant ovarian carcinoma. Nowadays, TREO is increasingly applied iv in high doses as a promising Myeloablative Agent with low organ toxicity in children. Under physiological conditions it undergoes pH-dependent transformation into epoxy-transformers (S,S-EBDM and S,S-DEB). The mechanism of this reaction is generally known, but not its kinetic details. In order to investigate kinetics of TREO transformation, HPLC method with refractometric detection for simultaneous determination of the three analytes in one analytical run has been developed for the first time.The samples containing TREO, S,S-EBDM, S,S-DEB and acetaminophen (internal standard) were directly injected onto the reversed phase column. To assure stability of the analytes and obtain their complete resolution, mobile phase composed of acetate buffer pH 4.5 and acetonitrile was applied. The linear range of the calibration curves of TREO, S,S-EBDM and S,S-DEB spanned concentrations of 20-6000, 34-8600 and 50-6000 µM, respectively. Intra- and interday precision and accuracy of the developed method fulfilled analytical criteria. The stability of the analytes in experimental samples was also established. The validated HPLC method was successfully applied to the investigation of the kinetics of TREO activation to S,S-EBDM and S,S-DEB. At pH 7.4 and 37 °C the transformation of TREO followed first-order kinetics with a half-life 1.5 h.
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HPLC method for determination of biologically active epoxy-transformers of treosulfan in human plasma: Pharmacokinetic application
Journal of pharmaceutical and biomedical analysis, 2011Co-Authors: Franciszek K. Główka, Michał Romański, Artur Teżyk, Czesław Żaba, Tomasz WróbelAbstract:Abstract Clinical trials demonstrated treosulfan (TREO) as a promising Myeloablative Agent prior to hematopoietic stem cell transplantation (HSCT). TREO is a specific pro-drug from which biologically active mono- (S,S-EBDM) and diepoxybutane (S,S-DEB) derivatives are formed in vitro or in vivo by a non-enzymatic pH and temperature-dependent intramolecular nucleophilic substitution. Following extraction of the plasma samples with a mixture of dichloromethane and acetonitrile, S,S-EBDM and S,S-DEB were derivatized with 3-nitrobenzenesulfonic acid (3-NBS) to UV-absorbing esters. Optimal temperature and time of derivatization as well as extraction method and also the effect of pH on TREO stability in plasma were established. Identity of the synthesized derivatives was confirmed by mass spectrometry. The post-derivatization mixture was purified from the excess of unreacted 3-NBS by extraction with water. The derivatization products and 2,2′-dinitrobiphenyl (internal standard) were separated on Nucleosil 100 C18 column using a mobile phase consisted of acetonitrile and water. The developed method was validated and demonstrated adequate accuracy and precision. Limit of quantification for both S,S-EBDM and S,S-DEB amounted to 2.5 μM. The method was applied in clinical conditions to quantify the levels of TREO activation products in plasma of children undergoing HSCT. The methodology for simultaneous determination of TREO epoxy-transformers in human plasma is described for the first time.
William M. Atkins - One of the best experts on this subject based on the ideXlab platform.
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The Myeloablative Drug Busulfan Converts Cysteine to Dehydroalanine and Lanthionine in Redoxins.
Biochemistry, 2016Co-Authors: Michele Scian, Miklos Guttman, Samantha Diane Bouldin, Caryn E. Outten, William M. AtkinsAbstract:The Myeloablative Agent busulfan (1,4-butanediol dimethanesulfonate) is an old drug that is used routinely to eliminate cancerous bone marrow prior to hematopoietic stem cell transplant. The Myeloablative activity and systemic toxicity of busulfan have been ascribed to its ability to cross-link DNA. In contrast, here we demonstrate that incubation of busulfan with the thiol redox proteins glutaredoxin or thioredoxin at pH 7.4 and 37 °C results in the formation of putative S-tetrahydrothiophenium adducts at their catalytic Cys residues, followed by β-elimination to yield dehydroalanine. Both proteins contain a second Cys, in their catalytic C-X-X-C motif, which reacts with the dehydroalanine, the initial Cys adduct with busulfan, or the S-tetrahydrothiophenium, to form novel intramolecular cross-links. The reactivity of the dehydroalanine (DHA) formed is further demonstrated by adduction with glutathione to yield a lanthionine and by a novel reaction with the reducing Agent tris(2-carboxyethyl)phosphine (TCEP), which yields a phosphine adduct via Michael addition to the DHA. Formation of a second quaternary organophosphonium salt via nucleophilic substitution with TCEP on the initial busulfan-protein adduct or on the THT(+)-Redoxin species is also observed. These results reveal a rich potential for reactions of busulfan with proteins in vitro, and likely in vivo. It is striking that several of the chemically altered protein products retain none of the atoms of busulfan, in contrast to typical drug-protein adducts or traditional protein modification reAgents. In particular, the ability of a clinically used drug to convert Cys to dehydrolanine in intact proteins, and its subsequent reaction with biological thiols, is unprecedented.
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The Myeloablative Drug Busulfan Converts Cysteine to Dehydroalanine and Lanthionine in Redoxins
2016Co-Authors: Michele Scian, Miklos Guttman, Samantha Diane Bouldin, Caryn E. Outten, William M. AtkinsAbstract:The Myeloablative Agent busulfan (1,4-butanediol dimethanesulfonate) is an old drug that is used routinely to eliminate cancerous bone marrow prior to hematopoietic stem cell transplant. The Myeloablative activity and systemic toxicity of busulfan have been ascribed to its ability to cross-link DNA. In contrast, here we demonstrate that incubation of busulfan with the thiol redox proteins glutaredoxin or thioredoxin at pH 7.4 and 37 °C results in the formation of putative S-tetrahydrothiophenium adducts at their catalytic Cys residues, followed by β-elimination to yield dehydroalanine. Both proteins contain a second Cys, in their catalytic C-X-X-C motif, which reacts with the dehydroalanine, the initial Cys adduct with busulfan, or the S-tetrahydrothiophenium, to form novel intramolecular cross-links. The reactivity of the dehydroalanine (DHA) formed is further demonstrated by adduction with glutathione to yield a lanthionine and by a novel reaction with the reducing Agent tris(2-carboxyethyl)phosphine (TCEP), which yields a phosphine adduct via Michael addition to the DHA. Formation of a second quaternary organophosphonium salt via nucleophilic substitution with TCEP on the initial busulfan-protein adduct or on the THT+-Redoxin species is also observed. These results reveal a rich potential for reactions of busulfan with proteins in vitro, and likely in vivo. It is striking that several of the chemically altered protein products retain none of the atoms of busulfan, in contrast to typical drug-protein adducts or traditional protein modification reAgents. In particular, the ability of a clinically used drug to convert Cys to dehydrolanine in intact proteins, and its subsequent reaction with biological thiols, is unprecedented
