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Article
Functionalization of unactivated carbons in 3α,6- and 3α,24-dihydroxy-5β-cholane derivatives by dimethyldioxirane
Direct remote functionalization of unactivated carbons by dimethyldioxirane (DMDO) was examined for 3α,6- and 3α,24-dihydroxy-5β-cholane derivatives. DMDO oxidation of stereoisomeric methyl 3α,6-diacetoxy-5β-c...
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Article
An Improved Method for the Capillary Gas Chromatographic Derivatization of Polyhydroxylated Steroids Having tert-Hydroxyl Groups
An improved method for a suitable derivatization of polyhydroxylated steroids having one or two tert-hydroxyl groups at the 5β-, 14α-, 17α-, 24-, and/or 25-positions by capillary gas chromatography (CGC) is descr...
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Article
Biomimetic oxidation of unactivated carbons in steroids by a model of cytochrome P-450, oxorutheniumporphyrinate complex
Biomimetic oxidation of unactivated carbons for structurally different steroids was studied with a model of cytochrome P-450, oxorutheniumporphyrinate complex, which is generated in situ by 2,6-dichloropyridine N
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Article
Lupane triterpenes with a carbonyl group at C-20 induce cancer cell apoptosis
We evaluated the effects of various lupane triterpenes on B16 2F2 mouse melanoma cell differentiation and proliferation. All of the compounds tested (numbered 1–6) induced melanogenesis of B16 2F2 cells, a marker...
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Article
Stereoselective Synthesis and NMR Characterization of C-24 Epimeric Pairs of 24-Alkyl Oxysterols
Two pairs of C-24 epimeric (24R)-/(24S)-24-hydroxy-24-methyl-5α-cholestan-3β-yl acetates and (24R)-/(24S)-25-hydroxy-24-methyl-5α-cholestan-3β-yl acetates as well as some related 24-ethyl oxysterol analogs were s...
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Article
Analysis of urinary vitamin D3 metabolites by liquid chromatography/tandem mass spectrometry with ESI-enhancing and stable isotope-coded derivatization
The determination of the urinary vitamin D3 metabolites might prove helpful in the assessment of the vitamin D status. We developed a method for the determination of trace vitamin D3 metabolites, 25-hydroxyvitami...
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Article
Development and validation of the simultaneous measurement of four vitamin D metabolites in serum by LC–MS/MS for clinical laboratory applications
The quantification of serum 25-hydroxyvitamin D [25(OH)D] as an indicator of vitamin D status is currently primarily conducted by immunoassays, yet LC–MS/MS would allow more accurate determination. Furthermore...
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Article
A Method for Quantification of Tetrahydroglucocorticoid Glucuronides in Human Urine by LC/MS/MS with Isotope-coded Derivatization
The determination of urinary tetrahydroglucocorticoid (THGC) glucuronides might prove helpful in the diagnosis, pathophysiological analysis and assessment of the therapeutic efficacy of the diseases caused by ...
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Article
Changes in Polyamine Content in Rice Bran due to Fermentation with Aspergillus oryzae Analyzed by LC/ESI-MS/MS Combined with Derivatization
Many studies have demonstrated that the dietary supplementation of polyamines, especially spermidine (SPD), prevents age-related diseases. Rice bran is rich in polyamines and their amounts could be increased b...
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Article
Enhancing LC/ESI-MS/MS Throughput for Plasma Bile Acid Assay by Derivatization-based Sample-Multiplexing
Liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) enables the accurate and precise quantification of various analytes at very low concentrations, but it has room for improve...
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Article
An LC/MS/MS method for quantifying testosterone and dehydroepiandrosterone sulfate in four different serum samples during a single run
Simultaneous measurements of the circulating testosterone (TS) and dehydroepiandrosterone sulfate (DHEAS) are deemed to be helpful for the assessment of men’s health. Liquid chromatography/electrospray ionizat...
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Article
Improvement of analysis throughput for LC/MS assay
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Article
Separation and identification of monoglucuronides of vitamin D3 metabolites in urine by derivatization-assisted LC/ESI–MS/MS using a new Cookson-type reagent
A liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI–MS/MS) method was developed using a new Cookson-type reagent, 4-[4-(1-pipelidinyl)phenyl]-1,2,4-triazoline-3,5-dione (PIPTAD), t...