The Experts below are selected from a list of 555 Experts worldwide ranked by ideXlab platform
Marc Poirot - One of the best experts on this subject based on the ideXlab platform.
-
Improvement of 5,6α-epoxycholesterol, 5,6β-epoxycholesterol, cholestane-3β,5α,6β-triol and 6-oxo-cholestan-3β,5α-diol recovery for quantification by GC/MS
Chemistry and Physics of Lipids, 2017Co-Authors: Régis Soules, Emmanuel Noguer, Luigi Iuliano, Chiara Zerbinati, Julie Leignadier, Arnaud Rives, Philippe De Medina, Sandrine Silvente-poirot, Marc PoirotAbstract:5,6α-epoxycholesterol (5,6α-EC) and 5,6β-epoxycholesterol (5,6β-EC) are oxysterols involved in the anticancer pharmacology of the widely used antitumor drug tamoxifen. They are both metabolized into cholestane-3β,5α,6β-triol (CT) by the cholesterol-5,6-epoxide hydrolase (ChEH) enzyme, and CT is metabolized by an as-yet uncharacterized enzyme into 6-oxo-cholestan-3β,5α-diol (OCDO). A recent feasibility study showed that the 5,6-ECs may represent surrogate markers of tamoxifen activity in breast cancer patients undergoing endocrine therapy, thus there is a growing interest in their accurate quantification. These oxysterols are usually quantified by gas-liquid chromatography coupled to mass spectrometry (GC/MS), using an isotope dilution methodology with the corresponding deuterated oxysterol. This method is considered to be relative quantitative since all of the standards used are deuterated oxysterols, however it is not known whether the preparation of each oxysterol is affected in the same way by the extraction, pre-purification by solid phase extraction (SPE) and Trimethylsilylation steps, particularly when using biological samples that contain many other reactive compounds. Thus, in this study we investigated the yield of the 5,6-ECs, CT and OCDO recovery from patient serum samples at different stages of their work-up and Trimethylsilylation prior to GC/MS analysis, using [14C]-labeled analogs to follow these oxysterols at each step. We measured a 40 to 60% loss of material for the 5,6-ECs and OCDO, however we also describe the conditions that improved their recovery. Our data also show that the use of deuterated 5,6α-EC, 5,6β-EC, CT and OCDO is an absolute requirement for their accurate quantification.
Mohammad Ali Zolfigol - One of the best experts on this subject based on the ideXlab platform.
-
application of a novel nano immobilization of ionic liquid on an mcm 41 system for Trimethylsilylation of alcohols and phenols with hexamethyldisilazane
Research on Chemical Intermediates, 2018Co-Authors: Mohammad Ali Zolfigol, Arash Ghorbanichoghamarani, Sami Sajjadifar, Farzaneh TamiAbstract:3-[(3-(Trisilyloxy)propyl)chloride]-1-methylimidazolium tribromide ionic liquid supported on MCM-41 [nano-MCM-41@(CH2)3-1-methylimidazole]Br3 as a novel heterogeneous nano-catalyst was easily prepared and characterized using FT-IR spectroscopy, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, differential thermal analysis, and differential thermogravimetric analysis. This catalyst was successfully applied for selective Trimethylsilylation of various alcohols (primary, secondary, and tertiary alcohols) and also various phenols using hexamethyldisilazane in dichloromethane at room temperature to their corresponding trimethylsilyl (TMS) ethers. This method has a lot of advantages such as short reaction time, good to excellent yield of products, and ease of recovering and reusing the catalyst.
-
as Efficient Catalysts for the Chemoselective Trimethylsilylation of Hydroxyl Group with 1,1,1,3,3,3-Hexamethyldisilazane (HMDS) under Mild Conditions
2015Co-Authors: Arash Ghorbani-choghamarani, Mohammad Ali Zolfigol, Maryam B Hajjamib, Kamal A Amani, Roia Ayazi-nasrabadicAbstract:A highly convenient method for the Trimethylsilylation of alcohols and phenols via treatment by hexamethyldisilazane in the presence of 1,3-dichloro-5,5-dimethylhydantoin (DCH) and/or trichloromel-amine (TCM) as a catalyst has been developed. A wide variety of hydroxyl groups were selectively pro-tected in CH2Cl2/CH3CN under mild conditions
-
Communication Trimethylsilylation of Hydroxyl Group with 1,1,1,3,3,3-
2015Co-Authors: Arash Ghorbani-choghamarani, Mohammad Ali Zolfigol, Maryam B Hajjamib, Shila JafaribAbstract:Tribromomelamine (TBM) can be used as a novel catalyst for the Trimethylsilylation of alcohols and phenols with 1,1,1,3,3,3-hexamethyldisilazane (HMDS). A wide variety of hydroxyl groups were selec-tively protected in CH2Cl2/CH3CN under mild conditions
-
h2 cryptand 222 2 br3 2 as a tribromide type catalyst for the Trimethylsilylation tetrahydropyranylation of alcohols
South African journal of chemistry, 2011Co-Authors: Gholamabbas Chehardoli, Mohammad Ali Zolfigol, Vahid Khakyzadeh, Hadi Gholami, Khodabakhsh NiknamAbstract:A stable organic tribromide, (H2-cryptand 222) 2+ (Br3 - )2 was utilized as an active catalyst for the Trimethylsilylation/ tetrahydropyranylation of alcohols. The method is general for the preparation of OH-protected aliphatic (acyclic and cyclic), aromatic, primary, secondary and tertiary alcohols. 2+ (Br3 - )2, Trimethylsilylation, tetrahydropyranylation, alcohols, tribromide, TMS-ether, THP-ether.
-
hio3 ki a new combination reagent for iodination of aromatic amines and Trimethylsilylation of alcohols and phenols through in situ generation of iodine under mild conditions
Arkivoc, 2010Co-Authors: Mohammad Ali Zolfigol, Ardeshir Khazaei, Eskandar Kolvari, Nadiya Koukabi, Hamid Soltani, Maryam Behjunia, Vahid KhakyzadehAbstract:A combination of iodic acid and potassium iodide has been used for Trimethylsilylation of alcohols and phenols in the presence of HMDS and iodination of aromatic amines. The reactions occur very rapidly to provide the products in good to high yields in dichloromethane at room temperature while the use of toxic and corrosive molecular iodine is avoided.
Régis Soules - One of the best experts on this subject based on the ideXlab platform.
-
Improvement of 5,6α-epoxycholesterol, 5,6β-epoxycholesterol, cholestane-3β,5α,6β-triol and 6-oxo-cholestan-3β,5α-diol recovery for quantification by GC/MS
Chemistry and Physics of Lipids, 2017Co-Authors: Régis Soules, Emmanuel Noguer, Luigi Iuliano, Chiara Zerbinati, Julie Leignadier, Arnaud Rives, Philippe De Medina, Sandrine Silvente-poirot, Marc PoirotAbstract:5,6α-epoxycholesterol (5,6α-EC) and 5,6β-epoxycholesterol (5,6β-EC) are oxysterols involved in the anticancer pharmacology of the widely used antitumor drug tamoxifen. They are both metabolized into cholestane-3β,5α,6β-triol (CT) by the cholesterol-5,6-epoxide hydrolase (ChEH) enzyme, and CT is metabolized by an as-yet uncharacterized enzyme into 6-oxo-cholestan-3β,5α-diol (OCDO). A recent feasibility study showed that the 5,6-ECs may represent surrogate markers of tamoxifen activity in breast cancer patients undergoing endocrine therapy, thus there is a growing interest in their accurate quantification. These oxysterols are usually quantified by gas-liquid chromatography coupled to mass spectrometry (GC/MS), using an isotope dilution methodology with the corresponding deuterated oxysterol. This method is considered to be relative quantitative since all of the standards used are deuterated oxysterols, however it is not known whether the preparation of each oxysterol is affected in the same way by the extraction, pre-purification by solid phase extraction (SPE) and Trimethylsilylation steps, particularly when using biological samples that contain many other reactive compounds. Thus, in this study we investigated the yield of the 5,6-ECs, CT and OCDO recovery from patient serum samples at different stages of their work-up and Trimethylsilylation prior to GC/MS analysis, using [14C]-labeled analogs to follow these oxysterols at each step. We measured a 40 to 60% loss of material for the 5,6-ECs and OCDO, however we also describe the conditions that improved their recovery. Our data also show that the use of deuterated 5,6α-EC, 5,6β-EC, CT and OCDO is an absolute requirement for their accurate quantification.
Maryam Paktinat - One of the best experts on this subject based on the ideXlab platform.
-
efficient Trimethylsilylation and tetrahydropyranylation of alcohols in the presence of 1 3 dibromo 5 5 dimethylhydantoin
Synthesis, 2006Co-Authors: Farhad Shirini, Mohammad Ali Zolfigol, Maryam PaktinatAbstract:Chemoselective Trimethylsilylation and tetrahydropyranylation of benzylic and primary and secondary aliphatic alcohols proceed efficiently in the presence of 1,3-dibromo-5,5-dimethylhydantoin (DBH) under mild and completely heterogeneous reaction conditions in excellent yields.
Luigi Iuliano - One of the best experts on this subject based on the ideXlab platform.
-
Improvement of 5,6α-epoxycholesterol, 5,6β-epoxycholesterol, cholestane-3β,5α,6β-triol and 6-oxo-cholestan-3β,5α-diol recovery for quantification by GC/MS
Chemistry and Physics of Lipids, 2017Co-Authors: Régis Soules, Emmanuel Noguer, Luigi Iuliano, Chiara Zerbinati, Julie Leignadier, Arnaud Rives, Philippe De Medina, Sandrine Silvente-poirot, Marc PoirotAbstract:5,6α-epoxycholesterol (5,6α-EC) and 5,6β-epoxycholesterol (5,6β-EC) are oxysterols involved in the anticancer pharmacology of the widely used antitumor drug tamoxifen. They are both metabolized into cholestane-3β,5α,6β-triol (CT) by the cholesterol-5,6-epoxide hydrolase (ChEH) enzyme, and CT is metabolized by an as-yet uncharacterized enzyme into 6-oxo-cholestan-3β,5α-diol (OCDO). A recent feasibility study showed that the 5,6-ECs may represent surrogate markers of tamoxifen activity in breast cancer patients undergoing endocrine therapy, thus there is a growing interest in their accurate quantification. These oxysterols are usually quantified by gas-liquid chromatography coupled to mass spectrometry (GC/MS), using an isotope dilution methodology with the corresponding deuterated oxysterol. This method is considered to be relative quantitative since all of the standards used are deuterated oxysterols, however it is not known whether the preparation of each oxysterol is affected in the same way by the extraction, pre-purification by solid phase extraction (SPE) and Trimethylsilylation steps, particularly when using biological samples that contain many other reactive compounds. Thus, in this study we investigated the yield of the 5,6-ECs, CT and OCDO recovery from patient serum samples at different stages of their work-up and Trimethylsilylation prior to GC/MS analysis, using [14C]-labeled analogs to follow these oxysterols at each step. We measured a 40 to 60% loss of material for the 5,6-ECs and OCDO, however we also describe the conditions that improved their recovery. Our data also show that the use of deuterated 5,6α-EC, 5,6β-EC, CT and OCDO is an absolute requirement for their accurate quantification.
