Arimistane: Degradation product or metabolite of 7-oxo-DHEA?

RATIONALE: The instability of androst-5-ene-3,7-dione structures under acidic conditions is known. The formation of arimistane from 7-oxo-DHEA, influenced by the conditions of sample extraction, and mainly derivatization reaction and gas chromatography (GC) injector temperature, was described earlier, potentially leading to misinterpretation of results. By using a liquid chromatography (LC)-mass spectrometry (MS) (LC-MS) we investigated the stability of the 7-oxo-DHEA in two different solvents (methanol and dimethyl sulfoxide [DMSO]), and the arimistane formation after the application common analytical procedures. Additionally, in vitro and in vivo studies of 7-oxo-DHEA were performed. METHODS: The stability of 7-oxo-DHEA was studied in solutions after 60 days storage at -20°C. In vitro studies were performed by incubating 7-oxo-DHEA with human liver microsomes (HLMs). Healthy volunteers collected urine samples before and after the administration of a single dose of 7-oxo-DHEA. Analyses were performed using high-performance LC (HPLC) coupled to a triple quadrupole mass spectrometer (MS/MS) and GC combustion isotope ratio mass spectrometry (GC-C-IRMS) following HPLC purification. RESULTS: 7-oxo-DHEA was stable after 60 days in DMSO while a protic solvent as methanol promotes the degradation of 7-oxo-DHEA to arimistane. HLM incubations showed no formation of arimistane and the sample preparation only influenced the degradation of 7-oxo-DHEA when solvolysis was applied. After the administration study the presence of arimistane also after the hydrolysis with ß-glucuronidase (Escherichia coli) was observed while using ß-glucuronidase/arylsulfatase (Helix pomatia) showed the presence of arimistane already in blank samples collected before administration. CONCLUSIONS: Our results confirm arimistane as a valuable diagnostic marker of 7-oxo-DHEA administration, but also indicate that its formation is due to degradation processes rather than to metabolic biotransformation reactions.

Biohydroxylation of 7-oxo-DHEA, a natural metabolite of DHEA, resulting in formation of new metabolites of potential pharmaceutical interest.

Metabolism of steroids in healthy and unhealthy human organs is the subject of extensive clinical and biomedical studies. For this kind of investigations, it is essential that the reference samples of new derivatives of natural, physiologically active steroids (especially those difficult to achieve in the chemical synthesis) become available. This study demonstrated for the first time transformation of 7-oxo-DHEA-a natural metabolite of DHEA, using Syncephalastrum racemosum cells. The single-pulse fermentation of substrate produced two new hydroxy metabolites: 1ß,3ß-dihydroxy-androst-5-en-7,17-dione and 3ß,12ß-dihydroxy-androst-5-en-7,17-dione, along with the earlier reported 3ß,9α-dihydroxy-androst-5-en-7,17-dione and 3ß,17ß-dihydroxy-androst-5-en-7-one. Simultaneously, the same metabolites, together with small quantities of 7α- and 7ß-hydroxy-DHEA, as well as the products of their reduction at the C-17 were obtained after transformation of DHEA under pulse-feeding of the substrate. The observed reactions suggested that this micro-organism contains enzymes exhibiting similar activity to those present in human cells. Thus, the resulting compounds can be considered as potential components of the eukaryotic, including human, metabolome.

Synthesis of 3α-deuterated 7α-hydroxy-DHEA and 7-oxo-DHEA and application in LC-MS/MS plasma analysis.

7-Oxygenated metabolites of dehydroepiandrosterone (DHEA) are known for their neuroprotective and immunomodulatory properties. These neuroactive steroids are currently predominately analysed by mass spectrometry, for which the use of internal deuterated standards is necessary. The aim of this study was to synthesize the deuterated derivatives of 7α-hydroxy-DHEA and 7-oxo-DHEA and test them in liquid chromatography-tandem mass spectrometry (LC-MS/MS) in order to enhance the performance characteristics of this method. Here we report the synthesis of 3α deuterium-labelled 7α-hydroxy-DHEA and 7-oxo-DHEA. Deuterium was introduced into the 3α position by reduction of the corresponding 3-ketone with a protected 17-carbonyl group using NaBD4. Our new procedure allows the easier synthesis of deuterated steroid labelled compounds. The use of these deuterated steroids enabled us to improve the human plasma LC-MS/MS analysis of 7α-hydroxy-DHEA and 7-oxo-DHEA in terms of sensitivity, precision and recovery.

A validated LC-MS/MS method for the sensitive quantitation of serum 7alpha hydroxy-, 7beta hydroxy- and 7keto-dehydroepiandrosterone using a novel derivatization reagent.

7alpha hydroxy-, 7beta hydroxy- and 7keto-dehydroepiandrosterone (7α OH-DHEA, 7ß OH-DHEA and 7 oxo-DHEA) are oxidized metabolites of dehydroepiandrosterone (DHEA). Their concentrations are low in the circulation, especially in postmenopausal women, thus resulting in a considerable challenge for their reliable measurement. A sensitive and accurate LC-MS/MS method has been developed using a simple sample preparation procedure and a novel derivatization with 1-amino-4-methyl piperazine (MP). The derivatized metabolites are stable in high water content reagents. A 10 pg/mL (0.2 pg on column) for the low limit of quantitation (LLOQ) has been achieved for all three compounds. A proper choice of multiple reaction monitoring (MRM) transitions provides good specificity. The excess amount of reagent can be removed from the sample during the derivatization process. Within the calibration range of 10-2000 pg/mL, a good linearity was obtained with R>0.99 where the weighing factor is 1/X while the bias and coefficient of variance (CV) are within 8% for all levels of QCs and calibration curves. This method has been fully validated according to the FDA guidelines, where the results of the matrix effect meet the acceptance criteria while freeze-thaw stability, short and long term stability in matrix and solution as well as post-processed sample stability meet the requirements. With this method, the concentrations of 7α OH-DHEA, 7ß OH-DHEA and 7 oxo-DHEA were measured in premenopausal and postmenopausal serum. The average concentration of 7α OH-DHEA is equivalent to that of 7ß OH-DHEA in both types of sera.

Dehydroepiandrosterone and 7-oxo-dehydroepiandrosterone (7-oxo-DHEA) protected hippocampal neurons against neurotoxicity induced by glutamate / 中国药理学通报

Aim To study Dehydroepiandrosterone (DHEA) and 7-oxo-dehydroepiandrosterone (7-oxo-DHEA) protected hippocampal neurons against neurotoxicity induced by glutamate(Glu). Methods Cell survival rate was analyzed using MTT colorimetry, the change of Ca 2+ levels and the levels of free radical in cultured hippocampal neurons were analyzed by the laser scanning confocal microscope, and cellular GSH level was also analyzed. Results Exposure of cultured rat hippocampal neurons to Glu resulted in accumulation of celluar Ca 2+ and cellular free radical were prevented by DHEA (0.1 ?mol?L -1 )and 7-oxo-DHEA(0.1 ?mol?L -1),and cellular GSH was increased. Conclusion DHEA and 7-oxo-DHEA protected hippocampal neurons against neurotoxicity induced by Glu.