Parallel derivatization strategy coupled with liquid chromatography-mass spectrometry for broad coverage of steroid hormones.

Steroid hormones are a type of crucial substances that mediate numerous vital physiological functions. The comprehensive detection of steroid hormones can help understand the physiopathologic mechanism of steroid hormone-related diseases. It is very difficult to determine steroid hormones in biological samples due to their low endogenous concentrations and poor ionization efficiency. In this study, an efficient and sensitive approach was developed for profiling steroid hormones by combining liquid-liquid extraction and parallel derivatization with liquid chromatography-tandem mass spectrometry. Methoxyamine and dansyl chloride were used to derivatize steroid hormones containing carbonyl and phenolic hydroxyl groups, respectively. Our established method achieved simultaneous analysis of carbonyl and phenolic hydroxyl-containing steroid hormones and could cover estrogens, androgens, corticoids and progestogens. Twenty-nine steroid hormones were detected at pg/mL levels with the sensitivity enhanced by three orders of magnitude after derivatization. The linearity (with linear range of 2-4 orders of magnitude), precision (less than 15%) and recovery (71.1-128.7%) were satisfactory for quantitative analysis of steroid hormones. Finally, the established method was successfully employed to the determination of steroid hormones in serum samples of healthy males and females as well as ovarian cancer patients. The results showed that this approach was suitable and reliable for routine test of steroid hormones containing carbonyl and phenolic hydroxyl groups.

Antenatal/early postnatal hypothyroidism increases the contribution of Rho-kinase to contractile responses of mesenteric and skeletal muscle arteries in adult rats.

BACKGROUND: Maternal thyroid deficiency can increase Rho-kinase procontractile influence in arteries of 2-week-old progeny. Here we hypothesized that augmented role of Rho-kinase persists in arteries from adult progeny of hypothyroid rats. METHODS: Dams were treated with 6-propyl-2-thiouracil (PTU) in drinking water (0.0007%) during pregnancy and 2 weeks postpartum; control (CON) females received PTU-free water. At the age of 10-12-weeks, serum T3/T4 levels did not differ between PTU and CON male offspring. Cutaneous (saphenous), mesenteric, and skeletal muscle (sural) arteries were studied by wire myography, qPCR, and Western blotting. RESULTS: Saphenous arteries of PTU and CON groups showed similar responses to α1-adrenoceptor agonist methoxamine and were equally suppressed by Rho-kinase inhibitor Y27632. Responses of mesenteric arteries also did not differ between PTU and CON, but the effects of Y27632 were more prominent in the PTU group. Sural arteries of PTU rats compared to CON demonstrated augmented responses to methoxamine, increased RhoA mRNA contents and higher levels of MYPT1 phosphorylation at Thr855. Intergroup differences in contractile responses and phospho-MYPT1-Thr855 were eliminated by Y27632. CONCLUSION: Rho-kinase contribution to contractile responses of mesenteric and especially sural arteries is augmented in adult PTU rats. Therefore, maternal thyroid deficiency may have long-term detrimental consequences for vasculature in adult offspring.

Factors influencing biased agonism in recombinant cells expressing the human α1A -adrenoceptor.

BACKGROUND AND PURPOSE: Agonists acting at GPCRs promote biased signalling via Gα or Gßγ subunits, GPCR kinases and ß-arrestins. Since the demonstration of biased agonism has implications for drug discovery, it is essential to consider confounding factors contributing to bias. We have examined bias at human α1A -adrenoceptors stably expressed at low levels in CHO-K1 cells, identifying off-target effects at endogenous receptors that contribute to ERK1/2 phosphorylation in response to the agonist oxymetazoline. EXPERIMENTAL APPROACH: Intracellular Ca2+ mobilization was monitored in a Flexstation® using Fluo 4-AM. The accumulation of cAMP and ERK1/2 phosphorylation were measured using AlphaScreen® proximity assays, and mRNA expression was measured by RT-qPCR. Ligand bias was determined using the operational model of agonism. KEY RESULTS: Noradrenaline, phenylephrine, methoxamine and A61603 increased Ca2+ mobilization, cAMP accumulation and ERK1/2 phosphorylation. However, oxymetazoline showed low efficacy for Ca+2 mobilization, no effect on cAMP generation and high efficacy for ERK1/2 phosphorylation. The apparent functional selectivity of oxymetazoline towards ERK1/2 was related to off-target effects at 5-HT1B receptors endogenously expressed in CHO-K1 cells. Phenylephrine and methoxamine showed genuine bias towards ERK1/2 phosphorylation compared to Ca2+ and cAMP pathways, whereas A61603 displayed bias towards cAMP accumulation compared to ERK1/2 phosphorylation. CONCLUSION AND IMPLICATIONS: We have shown that while adrenergic agonists display bias at human α1A -adrenoceptors, the marked bias of oxymetazoline for ERK1/2 phosphorylation originates from off-target effects. Commonly used cell lines express a repertoire of endogenous GPCRs that may confound studies on biased agonism at recombinant receptors.

Stereoselective Catalytic Synthesis of Active Pharmaceutical Ingredients in Homemade 3D-Printed Mesoreactors.

3D-printed flow reactors were designed, fabricated from different materials (PLA, HIPS, nylon), and used for a catalytic stereoselective Henry reaction. The use of readily prepared and tunable 3D-printed reactors enabled the rapid screening of devices with different sizes, shapes, and channel dimensions, aimed at the identification of the best-performing reactor setup. The optimized process afforded the products in high yields, moderate diastereoselectivity, and up to 90 % ee. The method was applied to the continuous-flow synthesis of biologically active chiral 1,2-amino alcohols (norephedrine, metaraminol, and methoxamine) through a two-step sequence combining the nitroaldol reaction with a hydrogenation. To highlight potential industrial applications of this method, a multistep continuous synthesis of norephedrine has been realized. The product was isolated without any intermediate purifications or solvent switches.

Analysis of oxidized glycerophosphocholine lipids using electrospray ionization mass spectrometry and microderivatization techniques.

Oxidized low-density lipoprotein (LDL) is thought to play an important role in atherogenesis and cardiovascular disease in humans. Oxidized LDL is a complex mixture of many oxidized species, including numerous oxidized glycerophospholipids. Electrospray ionization and tandem mass spectrometry as well as microchemical derivatization of high-performance liquid chromatographically purified fractions derived from oxidized LDL were investigated as means to determine the structure of individual components present in oxidized LDL. One major oxidized phosphocholine lipid had an [M + H](+) ion at m/z 650. Derivatization to the trimethylsilyl ether and methoxime caused shifts in mass which, along with negative ion collision-induced dissociation mass spectra, were consistent with the presence of three species, 1-palmitoyl-2-(9-oxononanoyl)glycerophosphocholine and two isomeric 1-octadecanoyl-2-(hydroxyheptenoyl)glycerophosphocholines. These species were chemically synthesized. Trimethylsilylation of free hydroxyl groups increased the mass of the phospholipid acyl chains containing hydroxyl groups by 72 u. Conversion of carbonyl groups to the methoxylamine derivative increased the mass by 29 u. Ozonolysis of those products which contained double bonds proved to be a facile technique to determine the position and number of double bonds present. The use of these techniques was illustrated in the structural characterization of one major component (m/z 650, positive ions) in oxidized LDL as 1-octadecanoyl-2-(7-hydroxyhepta-5-enoyl)glycerophosphocholi ne. A possible mechanism for the formation of this unique chain-shortened glycerophospholipid is proposed.