کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10848120 1070650 2005 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Formation of 19-norsteroids by in situ demethylation of endogenous steroids in stored urine samples
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Formation of 19-norsteroids by in situ demethylation of endogenous steroids in stored urine samples
چکیده انگلیسی
The formation of 19-norsteroids by demethylation of endogenous steroids in stored urine samples was observed. Suspicious urine samples (i.e. containing trace amounts of 19-norandrosterone and 19-noretiocholanolone) were selected and spiked with deuterated analogues of androsterone and etiocholanolone at concentrations corresponding to high endogenous levels (4 μg/mL). After incubation, respective 19-norsteroids (19-norandrosterone-d4 and 19-noretiocholanolone-d5) were identified in these samples by high-resolution mass spectrometry. The transformation of the 5β-isomer (etiocholanolone) yields about three-fold higher concentrations, compared to the 5α-isomer. A significant temperature dependence was observed by comparison of reaction kinetics at room temperature (23 ± 2 °C) and 37 °C. Concentrations of 19-norandrosterone-d4 and 19-noretiocholanolone-d5, respectively, were 2.7 and 3.6 times higher at elevated temperature. The conversion of androsterone-d4 to 19-norandrosterone-d4 did not exceed a relative amount of 0.1%. Incubation of the urine samples with androsterone-d4-glucuronide led to the production of 19-norandrosterone-d4-glucuronoide. A partial stabilization was observed after addition of metabolic inhibitors (e.g. EDTA). The application of the incubation experiments described may contribute to the clarification of adverse analytical findings regarding low levels of 19-norsteroid metabolites.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Steroids - Volume 70, Issue 8, July 2005, Pages 499-506
نویسندگان
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