Development and validation of a high-performance liquid chromatography assay for the quantitative determination of 7-oxo-dehydroepiandrosterone-3beta-sulfate in human plasma

A systematic review of the impact of 7-keto-DHEA on body weight

7-Keto-DHEA has been commercially advertised as a dietary supplement to support weight loss. The objective of the present systematic review it to summarize the evidence supporting the use of 7-keto-DHEA in overweight and obese population. The systematic search was conducted in Medline, Embase, Cochrane Library, CINAHL, Web of Science, Scopus, ICTRP, and ClinicalTrials.gov. Additionally, reference lists of eligible studies were considered, and authors of relevant studies were contacted. Two authors independently screened the studies against the inclusion criteria and assessed their risk of bias. In total, 4 out of 686 studies were included in the review. They all held a low risk of bias. Half of them showed a significant reduction in body weight. One study found a decrease in body fat percentage and another one reported a decrease in BMI. Two studies stated an increase in resting metabolic rate. No serious adverse effects were reported. Various possible mechanisms in favor of weight loss are discussed; however, with the evidence currently available, no clear answer can be given regarding 7-keto-DHEA and weight loss. Further studies need to be conducted to clarify the efficacy and safety of this drug before it can be recommended for therapeutic use.

Liquid chromatographic method development for steroids determination (corticoids and anabolics)

A LC isocratic separation study of a complex mixture containing 18 steroids (corticoids and anabolics), used potentially as growth promoters, was carried out. For this purpose, using a Hypersil ODS column at controlled temperature, mobile phases (from binary to quaternary) prepared from water and MeOH, ACN or THF as organic modifiers and UV detection at 245 nm, were employed (dehydroepiandrosterone was detected at 200 nm). The optimum separation was achieved using water/acetonitrile (65:35, v/v) as mobile phase at 30 degrees C, allowing the separation of 16 out of 18 steroids in about 30 min. The retention scale using optimized binary mobile phases was related with steroids hydrophobicity and structure, allowing a classification into three groups for these compounds. To improve the separation several alkyl-silica packings were tested: Type A (Lichrospher C8) and Type B (Luna C18, Kromasil C18, Purospher C18 and Synergy C12). Taking into account resolution, number of separated compounds and run time analysis the Hypersil column was selected as the best choice for further applications. Calibration graphs were obtained using fluorocortisone, fluoxymesterone or methylprednisolone as internal standard. The optimized separation was applied to the analysis of piglet feed samples spiked with steroids. The sample preparation process included solvent extraction using diethyleter and solid phase extraction using silica cartridges. The recoveries were in the range 70-92%. Decision limits and detection capability were in the range 34-198 and 41-249 microg/kg, respectively. Repeatability was also evaluated.

A novel radioimmunoassay of 7-oxo-DHEA and its physiological levels

A novel radioimmunoassay (RIA) of unconjugated 7-oxo-dehydroepiandrosterone (7-oxo-DHEA) in human serum was developed for the first time. This steroid is an intermediate in the biosynthesis of immunomodulatory 7-hydroxylated DHEA metabolites, and has been shown to possess thermogenic properties. The method employs polyclonal rabbit antiserum to (19E)-3beta-hydroxy-7,17,19-trione-19-O-(carboxymethyloxime):BSA conjugate and a homologous radioiodinated derivative with tyrosine methyl ester. The cross reactivity of the antiserum with structurally closest 7-hydroxyepimers of DHEA was lower than 1.7%, with DHEA 0.4%, with all other related steroid less than 0.4%. The method includes ether extraction of serum (0.5 ml), followed by RIA. Its detection limit was 0.06 pmol (18 pg)/tube, the average intra- and inter-assay coefficients of variation were 4.1% and 8.3%, respectively. Mean recovery of serum spiked with 7-oxo-DHEA varied between 78.8% and 112%. Its levels in three serum pools were compared with a low-resolution gas chromatography-mass spectrometry method with satisfactory results. The method has been used for determination of 7-oxo-DHEA in serum samples of 215 subjects (91 males and 124 females) without overt endocrine disorders, aged 5-71 years. The over-all mean+/-S.D. was 0.280+/-0.227, the median 0.239 nmol/l. No significant sex differences were recorded. The only group which differed significantly from all other ones were males below 10 years, significantly lower values than in other age groups were found also in the first two age groups of females.

Simultaneous determination of dehydroepiandrosterone and its 7-oxygenated metabolites in human serum by high-resolution gas chromatography--mass spectrometry

A highly sensitive and specific method has been developed for the simultaneous measurement of free (unconjugated) or sulfate-conjugated forms of dehydroepiandrosterone (DHEA), 7alpha-hydroxy-DHEA (7alpha-OH-DHEA), 7beta-hydroxy-DHEA (7beta-OH-DHEA), and 7-oxo-DHEA (7-oxo-DHEA) in human serum. This method is based upon a stable isotope-dilution technique by gas chromatography-selected-ion monitoring mass spectrometry. Free steroids were extracted from serum with an organic solvent and the sulfate-conjugated steroids remained in aqueous phase. Free steroids were purified by solid-phase extraction, while sulfate-conjugated steroids were hydrolyzed by sulfatase and deconjugated steroids were purified by solid-phase extractions. The extracts were treated with O-methylhydroxylamine hydrochloride and were subsequently dimethylisopropylsilylated. The resulting methyloxime-dimethylisopropylsilyl (MO-DMIPS) ether derivatives were quantified by gas chromatography-selected-ion monitoring mass spectrometry in a high-resolution mode. The detection limits of MO-DMIPS ether derivatives of DHEA, 7alpha-OH-DHEA, 7beta-OH-DHEA and 7-oxo-DHEA were 1.0, 0.5, 0.5 and 2.0pg, respectively. Coefficients of variation between samples ranged from 10.6 to 22.9% for free 7-oxygenated DHEA to less than 10% for DHEA and sulfate-conjugated 7-oxygenated DHEA. The concentrations of these steroids were measured in 18 sera samples from healthy volunteers (9 males and 9 females; aged 23-78 years). Free DHEA, 7alpha-OH-DHEA, 7beta-OH-DHEA and 7-oxo-DHEA levels ranged between 0.21-3.55, 0.001-0.194, 0.003-0.481, and 0.000-0.077ng/ml, respectively, and the sulfate-conjugated steroid levels of these metabolites ranged between 253-4681, 0.082-3.001, 0.008-0.903, and 0.107-0.803ng/ml, respectively. The free DHEA-related steroid concentrations were much lower than those previously measured by RIA and low-resolution GC-MS. The present method made it possible to determine simultaneously serum DHEA-related steroid levels with sufficient sensitivity and accuracy.

Ergosteroids VII: perchloric acid-induced transformations of 7-oxygenated steroids and their bio-analytical applications--a liquid chromatographic-mass spectrometric study

Sulfate esters of 7-oxo-delta(5)-steroids can be selectively and quantitatively hydrolyzed to the corresponding free steroids in the presence of carboxylic acid esters by solvolysis with perchloric acid in ethyl acetate at room temperature. Sulfates as well as carboxylic acid esters, methyl ethers, and ketals can be quantitatively converted to the corresponding 3,5-diene-7-one derivatives by heating with perchloric acid in methanol at 65 degrees C. The dienes have a strong UV absorption with maximum centered around 284 nm. These reactions have been used for the characterization and structural elucidation of 7-oxygenated-delta(5)-steroids that are present in complex biomatrices and can also be used for the quantitative estimation of total 7-oxo-delta(5)-steroids (free as well as conjugated) in biological matrices.

Gas chromatography and high-performance liquid chromatography of natural steroids

This review article underlines the importance of gas chromatography (GC), high-performance liquid chromatography (HPLC) and their hyphenated techniques using mass spectrometry (MS) for the determination of natural steroids, especially in human biological fluids. Steroids are divided into eight categories based on their structures and functions, and recent references using the above methodologies for the analysis of these steroids are cited. GC and GC-MS are commonly used for the determination of volatile steroids. Although HPLC is a widely used analytical method for the determination of steroids including the conjugated type in biological fluids, LC-MS is considered to be the most promising one for this purpose because of its sensitivity, specificity and versatility.

Ergosteroids IV: synthesis and biological activity of steroid glucuronosides, ethers, and alkylcarbonates

The 7-oxo derivative of dehydroepiandrosterone is more active than the parent steroid and is devoid of adverse side effects in rats, monkeys and humans. In anticipation of possible therapeutic use we have sought more active, longer lasting forms of 7-oxo- and 7beta-hydroxydehydroepiandrosterones. The 7-oxo- and 7-hydroxy steroids have been converted to glucuronides, ethers and carbonate esters. The syntheses of these compounds are described and their ability to induce the formation of liver thermogenic enzymes when fed to rats is reported. Some of the new derivatives were found to be somewhat more effective than the equimolar amounts of 7-oxo-DHEA with which they were compared in each experiment.

Quantification of urine 17-ketosteroid sulfates and glucuronides by high-performance liquid chromatography-ion trap mass spectroscopy

The measurement of androgen steroids has been utilized as a clinical indicator of adrenal function, androgen abuse, and as a prediction of general health or biological aging. An improved high-performance liquid chromatography-ion trap mass spectroscopic method with sonic spray ionization (SSI) technology for the quantification of individual urinary 17-ketosteroid sulfates and glucuronides was developed and validated. Sample preparation was simplified using a C18 cartridge followed by direct injection onto a reversed-phase HPLC column. Individual 17-ketosteroid from 63 urinary specimens collected in a 24-h period was measured. 17-Ketosteroid conjugates, total 17-KS-S and the ratio of total 17-KS-S to creatinine referred to herein as the Anabolic/Catabolic Index (ACI) showed statistically significant negative correlations with age.