Determination of dehydroepiandrosterone sulphate in biological samples by liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry using [7,7,16,16-2H4]-dehydroepiandrosterone sulphate as an internal standard

Quantification of BNN27, a novel neuroprotective 17-spiroepoxy dehydroepiandrosterone derivative in the blood and retina of rodents, after single intraperitoneal administration

BNN27 is a novel 17‐spiroepoxy derivative of the neurosteroid Dehydroepiandrosterone with neuroprotective properties. The purpose of this study was the detection and quantification of BNN27 after single intraperitoneal administration, in the serum and retina of normal rodents. Forty‐two C57BL/6 mice and 48 Sprague–Dawley rats were used for the quantification of BNN27 in the blood serum and retina, respectively. BNN27 was injected intraperitoneally (i.p.) at concentrations of 100 and 30 mg/kg of body weight (b.w.), respectively. The blood was collected with retro‐orbital bleeding and the retina was isolated after enucleation at various time points. The molecule concentrations were measured with Liquid chromatography‐mass spectrometry (LC‐MS). Non‐compartmental analysis was used to determine pharmacokinetic parameters. BNN27 was found to have an elimination constant k_el = 0.465 h⁻¹ and mean residence time (MRT) 2.154 h in the mouse serum. The maximum concentration (C_max) in the retina was detected at 2 h (tCmax) after intraperitoneal administration and was equal to 1100 ng/g. BNN27 is rapidly eliminated from both blood and retina. In the retina specifically, it is undetectable 6 h after injection. BNN27 shows a rapid systemic elimination as anticipated by its small size and lipophilicity. It is measurable in small peripheral tissues such as the rat retina, after one single i.p. injection, using a simple method such as LC‐MS. Its detection in the retina corroborates the existing biological data that the molecule crosses the blood–retinal barrier, highlighting it as a potential neuroprotective agent for retinal disease.

Adrenocorticotropin Acutely Regulates Pregnenolone Sulfate Production by the Human Adrenal In Vivo and In Vitro

BACKGROUND

Dehydroepiandrosterone sulfate (DHEAS) is the most abundant steroid in human circulation, and adrenocorticotropic hormone (ACTH) is considered the major regulator of its synthesis. Pregnenolone sulfate (PregS) and 5-androstenediol-3-sulfate (AdiolS) have recently emerged as biomarkers of adrenal disorders.

OBJECTIVE

To define the relative human adrenal production of Δ5-steroid sulfates under basal and cosyntropin-stimulated conditions.

METHODS

Liquid chromatography-tandem mass spectrometry was used to quantify three unconjugated and four sulfated Δ5-steroids in (1) paired adrenal vein (AV) and mixed venous serum samples (21 patients) and (2) cultured human adrenal cells both before and after cosyntropin stimulation, (3) microdissected zona fasciculata (ZF) and zona reticularis (ZR) from five human adrenal glands, and (4) a reconstituted in vitro human 17α-hydroxylase/17,20-lyase/(P450 17A1) system.

RESULTS

Of the steroid sulfates, PregS had the greatest increase after cosyntropin stimulation in the AV (32-fold), whereas DHEAS responded modestly (1.8-fold). PregS attained concentrations comparable to those of DHEAS in the AV after cosyntropin stimulation (AV DHEAS/PregS, 24 and 1.3 before and after cosyntropin, respectively). In cultured adrenal cells, PregS demonstrated the sharpest response to cosyntropin, whereas DHEAS responded only modestly (21-fold vs 1.8-fold higher compared with unstimulated cells at 3 hours, respectively). Steroid analyses in isolated ZF and ZR showed similar amounts of PregS and 17α-hydroxypregnenolone in both zones, whereas DHEAS and AdiolS were higher in ZR (P < 0.05).

CONCLUSION

Our studies demonstrated that unlike DHEAS, PregS displayed a prominent acute response to cosyntropin. PregS could be used to interrogate the acute adrenal response to ACTH stimulation and as a biomarker in various adrenal disorders.

Methods for determination of fingernail steroids by LC/MS/MS and differences in their contents between right and left hands

Fingernail clipping is expected to be a specimen for steroid testing, because it has several advantages over blood; i.e., noninvasive collection, ease of storage, portability and handling, and possibility for an assessment of the steroid status over a relatively long and retrospective time window. In this study, we examined whether there is a difference in the nail contents between the right and left hands for five steroids [glycochenodeoxycholic acid (GCDCA), taurochenodeoxycholic acid (TCDCA), dehydroepiandrosterone sulfate (DHEAS), testosterone (TST) and cortisol (CRT)] using newly developed liquid chromatography/electrospray ionization-tandem mass spectrometry methods. The nail contents between the hands were significantly different for GCDCA, TCDCA and DHEAS, whereas those of TST and CRT only slightly differed. These results might be due to the difference in the binding affinity of each steroid for the nail keratin. The relatively hydrophilic steroids, GCDCA, TCDCA and DHEAS, may be lost from nails in daily life due to their low affinity for keratin, which would produce differences in the nail contents between the hands. Thus, the fingernail GCDCA, TCDCA and DHEAS contents may be influenced by factors other than the disease; the nail analysis is inefficient in the diagnosis of the disease associated with these steroids. On the other hand, the nail analysis looks promising for evaluation of the status of TST and CRT, which are lipophilic and inferred to be tightly bound to the keratin. In fact, the nail TST content showed a significant sex difference, just like its serum/plasma concentration.

Bioanalytical LC-MS Method for the Quantification of Plasma Androgens and Androgen Glucuronides in Breast Cancer

The physiological and pathological development of the breast is strongly affected by the hormonal milieu consisting of steroid hormones. Mass spectrometry (MS) technologies of high sensitivity and specificity enable the quantification of androgens and consequently the characterization of the hormonal status. The aim of this study is the assessment of plasma androgens and androgen glucuronides, in the par excellence hormone-sensitive tissue of the breast, through the application of liquid chromatography-mass spectrometry (LC-MS). A simple and efficient fit-for-purpose method for the simultaneous identification and quantification of dehydroepiandrosterone sulfate (DHEAS), androstenedione (A4), androsterone glucuronide (ADTG) and androstane-3α, 17β-diol-17-glucuronide (3α-diol-17G) in human plasma was developed and validated. The presented method permits omission of derivatization, requires a single solid-phase extraction procedure and the chromatographic separation can be achieved on a single C18 analytical column, for all four analytes. The validated method was successfully applied for the analysis of 191 human plasma samples from postmenopausal women with benign breast disease (BBD), lobular neoplasia (LN), ductal carcinoma in situ and invasive ductal carcinoma (IDC). DHEAS plasma levels exhibited significant differences between LN, IDC and BBD patients (P < 0.05). Additionally, ADTG levels were significantly higher in patients with LN compared with those with BBD (P < 0.05).

Endocrine correlates of pregnancy in the ring-tailed lemur (Lemur catta): implications for the masculinization of daughters

Female ring-tailed lemurs (Lemur catta) are Malagasy primates that are size monomorphic with males, socially dominate males, and exhibit a long, pendulous clitoris, channeled by the urethra. These masculine traits evoke certain attributes of female spotted hyenas (Crocuta crocuta) and draw attention to the potential role of androgens in lemur sexual differentiation. Here, hormonal correlates of prenatal development were assessed to explore the possibility that maternal androgens may shape the masculine morphological and behavioral features of developing female lemurs. Maternal serum 17α-hydroxyprogesterone, dehydroepiandrosterone sulphate (DHEA-S), ∆⁴ androstenedione (androst-4-ene-3,17,dione), testosterone, and 17β-estradiol were charted throughout the 19 pregnancies of 11 ring-tailed lemurs. As in spotted hyenas, lemur pregnancies were associated with an immediate increase in androgen concentrations (implicating early maternal derivation), followed by continued increases across stages of gestation. Pregnancies that produced singleton males, twin males, or mixed-sex twins were marked by greater androgen and estrogen concentrations than were pregnancies that produced singleton or twin females, especially in the third trimester, implicating the fetal testes in late-term steroid profiles. Concentrations of DHEA-S were mostly below detectable limits, suggesting a minor role for the adrenals in androgen biosynthesis. Androgen concentrations of pregnant lemurs bearing female fetuses, although less than those of pregnant hyenas, exceeded preconception and postpartum values and peaked in the third trimester. Although a maternal (and, on occasion, fraternal) source of androgen may exist for fetal lemurs, further research is required to confirm that these steroids would reach the developing female and contribute to her masculinization.

Discovering oxysterols in plasma: a window on the metabolome

While the proteome defines the expressed gene products, the metabolome results from reactions controlled by such gene products. Plasma represents an accessible "window" to the metabolome both in regard of availability and content. The wide range of the plasma metabolome, in terms of molecular diversity and abundance, makes its comprehensive analysis challenging. Here we demonstrate an analytical method designed to target one region of the metabolome, that is, oxysterols. Since the discovery of their biological activity as ligands to nuclear receptors there has been a reawakening of interest in oxysterols and their analysis. In addition, the oxysterols, 24S- and 27-hydroxycholesterol, are currently under investigation as potential biomarkers associated with neurodegenerative disorders such as Alzheimer's disease and multiple sclerosis; widespread analysis of these lipids in clinical studies will require the development of robust, sensitive and rapid analytical techniques. In this communication we present results of an investigation of the oxysterols content of human plasma using a newly developed high-performance liquid chromatography-mass spectrometry (HPLC-MS) method incorporating charge-tagging and high-resolution MS. The method has allowed the identification in plasma of monohydroxylated cholesterol molecules, 7alpha-, 24S-, and 27-hydroxycholesterol; the cholestenetriol 7alpha,27-dihydroxycholesterol; and 3beta-hydroxycholest-5-en-27-oic acid and its metabolite 3beta,7alpha-dihydroxycholest-5-en-27-oic acid. The methodology described is also applicable for the analysis of other sterols in plasma, that is, cholesterol, 7-dehydrocholesterol, and desmosterol, as well as cholesterol 5,6- seco-sterols and steroid hormones. Although involving derivatization, sample preparation is straightforward and chromatographic analysis rapid (17 min), while the MS method offers high sensitivity (ng/mL of sterol in plasma, or pg on-column) and specificity. The methodology is suitable for targeted metabolomic analysis of sterols, oxysterols, and steroid hormones opening a "window" to view this region of the metabolome.

Rapid column-switching liquid chromatography/mass spectrometric assay for DHEA-sulfate in the plasma of patients with Alzheimer's disease

A simple and highly sensitive method for the quantification of dehydroepiandrosterone-3-sulfate (DHEAS) in human plasma was developed. DHEAS was directly determined in plasma using column-switching liquid chromatography/mass spectrometry (LC-MS). The plasma was filtered with a membrane filter. The filtrate was injected onto a pre-column without further sample preparation such as extraction or derivatization. The pre-column was washed with an aqueous solution to remove interference and the analyte was eluted into a reversed-phase C(18) analytical column for separation and detection using a column-switching valve. The calibration range of DHEAS was 0.01-10 micromol/L, and the linearity of the method was 0.999. The limit of detection (LOD) at a signal-to-noise (S/N) ratio of 3 was 5 nmol/L. The accuracy and precision (%CV) were less than 10% in within-day and day-to-day variations. To explore the relationship between Alzheimer's disease and the DHEAS level in human plasma, the concentrations of DHEAS in female patients with Alzheimer's disease (n = 20) and in normal female subjects (n = 20) were measured. The level of DHEAS was significantly decreased in the plasma of patients with Alzheimer's disease (p < 0.0002) compared with that in normal subjects. From the results, we concluded that our method is sufficiently sensitivity and reliability for the quantification of DHEAS in clinical samples. Plasma DHEAS concentration could be an important marker to understand the pathogenesis of Alzheimer's disease.

Evaluation of CD detection in an HPLC system for analysis of DHEA and related steroids

The biological importance of dehydroepiandrosterone (DHEA) is reflected by the fact that DHEA is a crucial precursor of the biosynthesis of the steroidal sex hormones. Simultaneous separation of DHEA, dehydroepiandrosterone sulfate (DHEA-S), pregnenolone, androstenedione and testosterone has been accomplished by reversed-phase ion-pair high-performance liquid chromatography (RP-IP-HPLC) based on isocratic elution applying circular dichroism (CD) detection at 295 nm. Addition of tetrabutylammonium hydrogensulfate to the mobile phase increases the retention of DHEA-S on the C8-silica column by an apparent ion-pairing mechanism without affecting the retention of the other (non-ionic) steroids. CD spectroscopy provides highly selective detection of compounds possessing optically active absorption bands and the separation is even more selective in the higher wavelength range applied. The linearity of the steroid concentration (c, mg mL(-1)) versus peak area was tested in the concentration range of 0.5-2 mg mL(-1) (injected quantities were 10-40 microg). The relative standard deviation (RSD) values for DHEA and DHEA-S indicated a good intra-assay and inter-assay precision of the method.

Neurosteroids in rat brain: extraction, isolation, and analysis by nanoscale liquid chromatography-electrospray mass spectrometry

A method designed for the analysis of sulfated neurosteroids and unconjugated ketonic neurosteroids in rat brain using nanoscale liquid chromatography-electrospray (nano-LC-ES) mass spectrometry is described. Neurosteroids in rat brain tissue were extracted, purified, and separated into two groups, neutral unconjugated steroids and steroid sulfates, by employing solid-phase partition, cation- and anion-exchange chromatography. The steroid sulfate fraction was analyzed by nano-LC-ES mass spectrometry. Contrary to expectations, the sulfates of pregnenolone and dehydroepiandrosterone (DHEA) were not detected. Internal standards, including pregnenolone sulfate, were recovered and the detection limit of the method was 0.3 ng/g of wet brain. Cholesterol sulfate was detected at a level of 1.2 microg/g of wet brain. The neutral unconjugated steroid fraction was derivatized with hydroxylamine hydrochloride to convert oxosteroids into their oximes. The oximes were isolated using cation-exchange chromatography and were analyzed by nano-LC-ES tandem mass spectrometry. The analyses of the neutral unconjugated steroid fraction confirmed the presence in rat brain of pregnenolone, pregnanolone isomers, progesterone, testosterone, and DHEA, which were characterized by their retention times, the mass of the protonated molecules, and characteristic fragment ions. The levels were estimated by addition of [3,4-(13)C(2)]-progesterone as an internal standard and found to be in a range of 0.04-20 ng/g.

Simultaneous determination of androstenediol 3-sulfate and dehydroepiandrosterone sulfate in human serum using isotope diluted liquid chromatography–electrospray ionization-mass spectrometry

A simple method for simultaneous determination of androstenediol 3-sulfate (Adiol-3S) and dehydroepiandrosterone sulfate (DHEA-S) in human serum using isotope diluted liquid chromatography-electrospray ionization-ion trap-mass spectrometry (LC-ESI-ion trap-MS) was developed. After addition of deuterated internal standards ([2H5]Adiol-3S and [2H4]DHEA-S), human serum (100 microl) was deproteinized with acetonitrile and then applied to a solid-phase extraction cartridge, Oasis HLB. The obtained steroid sulfates fraction was washed with hexane and then analyzed by LC-ESI-MS operated in the negative ion mode. The quantification ranges of Adiol-3S and DHEA-S were 10-400 ng/ml and 0.05-8 microg/ml, respectively. The method does not require the chemical or enzymatic hydrolysis of the conjugates and purification with high-performance liquid chromatography, and shows satisfactory reproducibility and accuracy. The concentrations of these sulfates in the sera of healthy male volunteers (n=14) were 19.2-245.3 mg/ml (Adiol-3S) and 0.175-5.16 microg/ml (DHEA-S), and those of patients with prostate cancer (n=19) were 15.3-182.7 ng/ml (Adiol-3S; four samples, not detectable) and 0.110-2.421 microg/ml (DHEA-S).

Hormones and prostate cancer: current perspectives and future directions

Prostate cancer is the most commonly diagnosed non-skin cancer in men in most western countries. Despite the high morbidity and mortality from prostate cancer, its etiology remains obscure. Although compelling laboratory data suggest a role for androgens in prostate carcinogenesis, most epidemiologic data on humans are inconclusive. To provide insights and directions for future epidemiologic research on hormones and prostate cancer, this review focuses on current perspectives of serum-based studies and polymorphisms in relevant hormone-related genes. We highlight the importance of methodologic studies and investigations of hormone levels in the prostatic tissue to help clarify the often-contradictory data on serologic studies. We recommend careful analysis and cautious interpretation of studies of genetic markers, including repeats and single nucleotide polymorphisms (SNPs), as false positive and negative results may arise in many current and future studies with limited statistical power and non-representative samples from the population. The review also highlights the reasons to perform functional analyses of SNPs, a critical and often under-appreciated component of molecular epidemiologic investigations. The time is ripe for large-scale multidisciplinary investigations that incorporate molecular genetics, biochemistry, histopathology, and endocrinology into traditional epidemiologic studies. Such collaboration will lead to a deeper understanding of the etiologic pathways of prostate cancer, ultimately yielding better preventive, diagnostic, and therapeutic strategies.

Analysis of ergosteroids. VIII: Enhancement of signal response of neutral steroidal compounds in liquid chromatographic-electrospray ionization mass spectrometric analysis by mobile phase additives

The signal response of moderately polar to nonpolar neutral steroidal compounds in positive ion mode was significantly improved in electrospray ionization mode by addition of volatile organic acids (trifluoroacetic acid, acetic and formic) at concentrations much lower than those normally employed for high-performance liquid chromatographic separations of ionic compounds. Each of the three acids enhanced the sensitivity, the order being: formic acid (approximately 50-200 ppm, v/v) > acetic acid (100-500 ppm) > trifluoroacetic acid (5-20 ppm). Higher concentrations caused decrease in the sensitivity. The extent of increase in the sensitivity was compound specific and also depended on the nature of organic modifier present in the mobile phase. Acetic acid was the acid of choice for the 'wrong-way-round' ionization of sulfate conjugates. The postcolumn addition of silver nitrate produced highly stable (M + Ag)+ adducts with concomitant increase in signal response and reduction in baseline noise.

High-performance liquid chromatographic analysis of dehydroepiandrosterone

Qualitative and quantitative analysis of dehydroepiandrosterone and its conjugates in biological matrices and establishment of their relationships with physiological functions is a very active field. This review article discusses methods of separation and quantification of dehydroepiandrosterone and its conjugates using high-performance liquid chromatographic techniques.

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.

Atmospheric pressure chemical ionization mass spectrometry for analysis of lipids

Atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) has proven to be a very valuable technique for analysis of lipids from a variety of classes. This instrumental method readily produces useful ions with gentle fragmentation from large neutral molecules such as triacylglycerols and carotenoids, which are often difficult to analyze using other techniques. Molecules that are easily ionized, such as phospholipids, produce molecular ions and diagnostically useful fragment ions that are complementary to those produced by methods such as electrospray ionization MS with collision-induced dissociation. The simplicity and versatility of APCI-MS make it an ideal tool for use in solving hitherto very difficult analytical problems.

Validation of an analytical procedure to measure trace amounts of neurosteroids in brain tissue by gas chromatography-mass spectrometry

A selective and extremely sensitive procedure has been developed and optimized, using high-performance liquid chromatography (HPLC), specific derivatization and gas chromatography-mass spectrometry (GC-MS), to simultaneously quantify very small amounts of different neurosteroids from rat brain. Unconjugated and sulfated steroids in brain extracts were separated by solid-phase extraction. The unconjugated fraction was further purified by HPLC, the steroids being collected in a single fraction, and the sulfated fraction was solvolyzed. All steroids were derivatized with heptafluorobutyric acid anhydride and analyzed by GC-MS (electron impact ionization) using selected-ion monitoring. High sensitivity and accuracy were obtained for all steroids. The detection limits were 1 pg for pregnenolone (PREG), dehydroepiandrosterone (DHEA) and their sulfate esters PREG-S and DHEA-S, 2 pg for progesterone (PROG) and 5 pg for 3alpha,5alpha-tetrahydroprogesterone (3alpha,5alpha-THP). In a pilot study on a rat brain, the concentrations of PREG-S and DHEA-S were 8.26+/-0.80 and 2.47+/-0.27 ng/g, respectively. Those of PREG, DHEA and PROG were 4.17+/-0.22, 0.45+/-0.02 and 1.95+/-0.10 ng/g, respectively. Good linearity and accuracy were observed for each steroid. The methodology validated here, allows femtomoles of neurosteroids, including the sulfates, found in small brain samples (at least equal to 10 mg) to be quantified simultaneously.

Analysis of oxosteroids by nano-electrospray mass spectrometry of their oximes

A method for the analysis of neutral oxosteroids by electrospray mass spectrometry is described. The oxosteroids are converted into their oximes by treatment with hydroxyammonium chloride in aqueous methanol. Intense peaks corresponding to protonated oxime molecules are observed in nano-electrospray mass spectra. The detection limits for the oximes of progesterone, pregnenolone and dehydroepiandrosterone were 2.5, 5 and 25 pg/microL, respectively, approximately 20 times lower than for the underivatised steroids. The signal intensities were proportional to the concentration of the steroids in the range of 500 to 2.5 pg/microL. Fragmentation by collision-induced dissociation (CID) was studied using oximes of 28 model steroids carrying an oxo group at C-3, C-17 or C-20. Some of the steroid oximes were labelled with deuterium or (15)N. Fragment ions were observed which yielded useful structural information. Upon CID, protonated oximes of 3-oxo-Delta(4)-steroids produced abundant ions by cleavage through the B-ring and by loss of the side chain, while protonated oximes of saturated 3-oxosteroids did not give abundant ions by cleavage through the B-ring. Protonated oximes of 20-oxosteroids unsubstituted at C-21, C-17 or C-16 produced a characteristic ion at m/z 86 containing the side chain, C-16 and C-17. Protonated oximes of steroids containing only a 17-oxo group gave fewer ions of diagnostic value. Coupled with the selective isolation of steroid oximes from a biological matrix this method of derivatisation and CID may be used for the analysis of neutral oxosteroids in biological samples.

Nano-electrospray tandem mass spectrometry for the analysis of neurosteroid sulphates

Neurosteroids are synthesised in the central and peripheral nervous system or are derived from peripheral sources, and act in the nervous system. In the present study we have evaluated the potential for using nano-electrospray (nano-ES) tandem mass spectrometry (MS/MS) for the structural analysis and detection of neurosteroids, in particular, steroid sulphates found in brain. Complete structural information can be obtained from 1 ng (3 pmol) of steroid sulphate, while fragment ions characteristic of the sulphate ester group can be obtained from only 3 pg (10 fmol) of sample. These values correspond to the expected quantities of steroid sulphates (e.g. pregnenolone sulphate) in about 100 mg and 300 microg of brain, respectively. Deuterated neurosteroid sulphates added to homogenised rat brain have been successfully analysed by nano-ES-MS/MS at a level of 50 pg/mg of brain.