HPLC–RIA analysis of steroid hormone profile in a virilizing stromal tumor of the ovary

Advances on Hormones and Steroids Determination: A Review of Voltammetric Methods since 2000

This article presents advances in the electrochemical determination of hormones and steroids since 2000. A wide spectrum of techniques and working electrodes have been involved in the reported measurements in order to obtain the lowest possible limits of detection. The voltammetric and polarographic techniques, due to their sensitivity and easiness, could be used as alternatives to other, more complicated, analytical assays. Still, growing interest in designing a new construction of the working electrodes enables us to prepare new measurement procedures and obtain lower limits of detection. A brief description of the measured compounds has been presented, along with a comparison of the obtained results.

LC-MS/MS based profiling and dynamic modelling of the steroidogenesis pathway in adrenocarcinoma H295R cells

Endocrine disrupting chemicals have been reported to exert effects directly on enzymes involved in steroid biosynthesis. Here, we present a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for profiling the steroid metabolome of H295R human adrenocarcinoma cells. Our method can simultaneously analyse 19 precursors, intermediates and end-products, representing the adrenal steroid biosynthesis pathway. In order to obtain better insights into the processes of steroidogenesis, we investigated the dose-response relationship of forskolin, an activator of adenylate cyclase, on steroid production in H295R cells. We observed that 1.5 μM forskolin stimulated steroid production at approximately 50% of the maximum rate for most steroids. Hence, we studied the time course for steroid synthesis over 72 h in H295R cells that were stimulated with forskolin. At 24 h, we observed a peak in steroid levels for the intermediate metabolites, such as progesterone and pregnenolone, while end-products such as testosterone and cortisol continued to increase until 72 h. Finally, we show how global data provide a unique basis to develop a comprehensive, dynamic model for steroidogenesis using first order kinetics. The timeline data made it possible to estimate all reaction rate constants of the network. We propose this method as a unique and sensitive screening tool to identify effects on adrenal steroidogenesis by endocrine disrupting compounds.

Determining estrogens using surface-assisted laser desorption/ionization mass spectrometry with silver nanoparticles as the matrix

We describe the application of silver nanoparticles (Ag NPs) as matrices for the determination of three estrogens using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Because Ag NPs have extremely high absorption coefficients (1.2 x 10(8) M(-1) cm(-1)) at 337 nm, they are effective SALDI matrices when using a nitrogen laser. Three tested estrogens--estrone (E1), estradiol (E2), and estriol (E3)--adsorb weakly onto the surfaces of the Ag NPs, through van der Waals forces. After centrifugation, the concentrated analytes adsorbed on the Ag NPs were subjected directly to SALDI-MS analyses, with the limits of detection for E1, E2, and E3 being 2.23, 0.23, and 2.11 microM, respectively. The shot-to-shot and batch-to-batch variations for the three analytes were less than 9% and 13%, respectively. We validated the practicality of this present approach through the quantitation of E2 in human urine. Using this approach, we determined the concentration of E2 in a sample of a pregnant woman's urine to be 0.16+/-0.05 microM (n=10).

HPLC-RIA analysis of the ectopic cortisol production in a cancerous pancreas tumor

Steroidal pathophysiology of a malignant, ACTH-producing pancreas tumor was investigated via HPLC-RIA determinations of intratissular concentrations of eleven main steroid hormones. The tumor specimen underwent extraction procedure with ethyl acetate and the extract was purified on a C18 minicolumn. Steroids were isolated by HPLC (C18-silica reversed phase stationary phase and methanol-water eluent system) and quantified by specific RIAs. Cortisol content of the tumor specimen was 15,700 pmol/g, the further steroid hormones were found in much lower concentrations (< 1.5-28 pmol/g). The extremely high cortisol concentration in the tissue witnesses the synthesis of the main glucocorticoid steroid in the ACTH-producing pancreas tumor and suggests a stimulating paracrine effect of ACTH on cortisol production. The present data verify that the determination of intratissular steroid concentrations by HPLC-RIA methods may identify even the most peculiar hormone sources and the hormone profiles facilitate studying pathophysiology of ectopic endocrine tumors.

Determination of estradiol and its degradation products by liquid chromatography

A novel HPLC method for simultaneous determination of estradiol and its seven degradation products in topical gel was developed. Zorbax SB-CN (150 mm x 4.6 mm, 5 microm) analytical column and mobile phase composed of acetonitrile, phosphoric acid 0.085%, and tetrahydrofurane (27:63:10, v/v/v) at flow-rate 1.0 ml min(-1) were used for the chromatographic separation using UV detection at 225 nm. The active substance estradiol was separated from all its known degradation products successfully. Two degradation products estrone and Delta(9(11))-estrone were not separated sufficiently, their peaks were evaluated as a sum of two components. The method was validated according to ICH guideline recommendations and thereafter it was successfully applied for stability tests of topical cream Estrogel HBF in the quality control laboratory. Limits of detection for degradation products ranged from 1.03 x 10(-5) to 1.14 x 10(-4) mg ml(-1), limits of quantitation for degradation products were in the range 3.43 x 10(-5) to 3.81 x 10(-4) mg ml(-1). The developed method is selective, precise, accurate and sensitive enough for determination of estradiol and its known degradation products.

Some remarks on characterization and application of stationary phases for RP-HPLC determination of biologically important compounds

Biologically active compounds such as vitamins, steroids, nucleosides, peptides and proteins play a very important role in coordinating living organism functions. Determination of those substances is indispensable in pathogenesis. Their complex structure and physico-chemical properties cause many analytical problems. Chromatography is the most common technique used in pharmaceutical and biomedical analysis. The interaction between analyte and stationary phase plays a major role in the separation process. The structure of the packing has a significant influence on the results of the separation process. Various types of spectroscopic techniques, such as nuclear magnetic resonance spectroscopy, infrared spectroscopy, fluorescence spectroscopy and photoacoustic spectroscopy can be useful tools for the characterization of packings. Surface area measurements, elemental analysis, thermal analysis and microcalorimetric measurements are also helpful in this field. Part of the paper contains a description of chromatographic tests used for the determination of column properties. The description of the possibilities of surface characterization is not complete, but is focused on the most popular techniques and practical chromatographic tests. All the presented methods made possible the design and quality control of a new generation stationary phases, which are the future of high-performance liquid chromatography.