Enantioselective endocrine disrupting effects of omeprazole studied in the H295R cell assay and by molecular modeling

Is the unique benzodiazepine structure interacting with CYP enzymes to affect steroid synthesis in vitro?

The aim of this project was to investigate the endocrine disrupting effects of three γ-aminobutyric acid type A receptor (GABA_AR) agonists, diazepam (DZ), oxazepam (OX) and alprazolam (AL) using the steroidogenic in vitro H295R cell line assay, a recombinant CYP17A1 assay, qPCR analysis and computational modelling. Similar effects for DZ and OX on the steroidogenesis were observed in the H295R experiment at therapeutically relevant concentrations. Progestagens and corticosteroids were increased up to 10 fold and androgens were decreased indicating CYP17A1 lyase inhibition. For DZ the inhibition on both the hydroxylase and lyase was confirmed by the recombinant CYP17A1 assay, whereas OX did not appear to directly affect the recombinant CYP17A1 enzyme. Androgens were decreased when exposing the H295R cells to AL, indicating a CYP17A1 lyase inhibition. However, this was not confirmed by the recombinant CYP17A1 assay but a down-regulation in gene expression was observed for StAR and CYP17A1. The present study showed that the three investigated benzodiazepines (BZDs) are rather potent endocrine disruptors in vitro, exerting endocrine effects close the therapeutic C_max. Both direct and indirect effects on steroidogenesis were observed, but molecular modelling indicated no direct interactions between the heme group in the steroidogenic CYP enzymes and the unique diazepin structure. In contrast, physicochemical properties such as high log P, structure and molecular weight similar to that of steroids appeared to influence the endocrine disrupting abilities of the investigated pharmaceuticals in vitro. Docking of the three BZDs in CYP17A1 and CYP21A2 confirmed that shape complementarity and hydrophobic effects seem to determine the binding modes.

Oral anti-diabetic drugs as endocrine disruptors in vitro - No evidence for additive effects in binary mixtures

Diabetes is one of the World's most concerning health problems and millions of patients are using anti-diabetic drugs (ADDs) in order to control blood glucose. The in vitro H295R steroidogenesis assay was implemented to investigate endocrine effects of three ADDs, metformin (MET), glimepiride (GLIM), sitagliptin (SIT) and the cholesterol-lowering drug simvastatin (SIM) individually and in three binary mixtures. Steroid hormones were analyzed using LC-MS/MS. Mixture effects were assessed by applying the Concentration Addition (CA) model. All tested drugs and binary mixtures interrupted the H295R steroidogenesis with different potency. The effects of MET:GLIM on the steroidogenesis were overall similar to the steroidogenic profile of GLIM, however effects were less pronounced. The binary mixture of MET:SIT showed overall minor effects on steroid production and only at very high concentrations. The SIM:SIT mixture showed inhibition downstream from cholesterol, which was attributed to the effects of SIM. The CA model partly predicted the effect of MET:SIT on some steroids but significantly overestimated the effects of MET:GLIM and SIM:SIT. Thus, the applicability of the CA model was limited and cocktail effects appeared to be intermediate responses of individual drugs, rather than additive. The complexity of dynamic pathways such as steroidogenesis appears to significantly reduce the use of the CA model. In conclusion, more dynamic models are needed to predict mixture effects in complex systems.

The anti-epileptic drug lamotrigine inhibits the CYP17A1 lyase reaction in vitro

The potential endocrine disrupting effects of the commonly prescribed anti-epileptic drug lamotrigine (LAM) were investigated using the H295R steroidogenic in vitro assay and computational chemistry methods. The H295R cells were exposed to different concentrations of LAM, and a multi-steroid LC-MS/MS method was applied to quantify the amount of secreted steroid hormones. LAM affected several steroid hormones in the steroidogenesis at therapeutic concentrations. All progestagens as well as 11-deoxycorticosterone and corticosterone increased 100-200% with increasing concentrations of LAM suggesting a selective inhibitory effect of LAM on CYP17A1, in particular on the lyase reaction. Recombinant CYP17A1 assay confirmed the competitive inhibition of LAM toward the enzyme with IC50 values of 619 and 764 μM for the lyase and the hydroxylase reaction, respectively. Levels of androstenedione and testosterone decreased at LAM concentrations above the therapeutic concentration range. The ability of LAM to bind to CYP17A1, CYP19A1, and CYP21A2 was investigated using docking and molecular dynamics simulations. This in silico study showed that LAM was able to bind directly to the heme iron in the active site of CYP17A1, but not CYP21A2, thus supporting the results of the in vitro studies. The molecular dynamics simulations also suggested binding of LAM to the heme iron in the CYP19A1 active site. No inhibition of the aromatase enzyme was, however, observed in the H295R assay. This could be due to a sequential effect within the steroidogenesis caused by the inhibition of CYP17A1, which reduced the amounts of androgens available for CYP19A1.

Application of molecular docking and PSO-SVR intelligent approaches in antimalarial activity prediction of enantiomeric cycloguanil analogues

A series of antifolate compounds, i.e. 1-(4-chlorophenyl)-6,6-dimethyl-1,3,5-triazine-2,4-diamine, or cycloguanil analogues, have shown effective inhibiting properties against Plasmodium falciparum dihydrofolate reductase (PfDHFR). In this work, the stereoselectivity of PfDHFR to the R and S enantiomer of cycloguanil analogues was obtained from molecular docking calculations and integrated into QSAR study to obtain a more accurate prediction model. Results indicate that PfDHFR can bind to cycloguanil analogues in the R and S enantiomers. Cycloguanil analogues with alkyl chain substituent prefer the R enantiomer over S because they do not experience steric hindrance with the Phe58 side chain, while cycloguanil analogues with phenol chain substituent prefer the S enantiomer over R because they do not experience steric hindrance with Leu46 and Met55 side chains. Particle swarm optimization and support vector regression were used to select relevant descriptors and generate the effective prediction model, with a high statistical significance level (r²_training = 0.941; r²_test = 0.884).

Pharmaceuticals, hormones, pesticides, and other bioactive contaminants in water, sediment, and tissue from Rocky Mountain National Park, 2012-2013

Pharmaceuticals, hormones, pesticides, and other bioactive contaminants (BCs) are commonly detected in surface water and bed sediment in urban and suburban areas, but these contaminants are understudied in remote locations. In Rocky Mountain National Park (RMNP), Colorado, USA, BCs may threaten the reproductive success and survival of native aquatic species, benthic communities, and pelagic food webs. In 2012-2013, 67 water, 57 sediment, 63 fish, 10 frog, and 12 quality-control samples (8 water and 4 sediment) were collected from 20 sites in RMNP. Samples were analyzed for 369 parameters including 149 pharmaceuticals, 22 hormones, 137 pesticides, and 61 other chemicals or conditions to provide a representative assessment of BC occurrence within RMNP. Results indicate that BCs were detected in water and/or sediment from both remote and more accessible locations in RMNP. The most commonly detected BCs in water were caffeine, camphor, para-cresol, and DEET; and the most commonly detected BCs in sediment were indole, 3-methyl-1H-indole, para-cresol, and 2,6-dimethyl-naphthalene. Some detected contaminants, including carbaryl, caffeine, and oxycodone, are clearly attributable to direct local human input, whereas others may be transported into the park atmospherically (e.g., atrazine) or have local natural sources (e.g., para-cresol). One or more pharmaceuticals were detected in at least 1 sample from 15 of 20 sites. Most of the 29 detected pharmaceuticals are excreted primarily in human urine, not feces. Elevated net estrogenicity was observed in 18% of water samples, and elevated vitellogenin in blood was observed in 12% of male trout, both evidence of potential endocrine disruption. Hormone concentrations in sediment tended to be greater than concentrations in water. Most BCs were observed at concentrations below those not expected to pose adverse effects to aquatic life. Results indicate that even in remote locations aquatic wildlife can be exposed to pharmaceuticals, hormones, pesticides, and other bioactive contaminants.

Interaction of metals from group 10 (Ni, Pd, and Pt) and 11 (Cu, Ag, and Au) with human blood δ-ALA-D: in vitro and in silico studies

Mammalian δ-aminolevulinate dehydratase (δ-ALA-D) is a metalloenzyme, which requires Zn(II) and reduced thiol groups for catalytic activity, and is an important molecular target for the widespread environmental toxic metals. The δ-ALA-D inhibition mechanism by metals of Group 10 (Ni, Pd, and Pt) and 11 (Cu, Ag, and Au) of the periodic table has not yet been determined. The objective of this study was to characterize the molecular mechanism of δ-ALA-D inhibition caused by the elements of groups 10 and 11 using in vitro (δ-ALA-D activity from human erythrocytes) and in silico (docking simulations) methods. Our results showed that Ni(II) and Pd(II) caused a small inhibition (~ 10%) of the δ-ALA-D. Pt(II) and Pt(IV) significantly inhibited the enzyme (75% and 44%, respectively), but this inhibition was attenuated by Zn(II) and dithiothreitol (DTT). In group 11, all metals inhibited δ-ALA-D with great potency (~ 70-90%). In the presence of Zn(II) and DTT, the enzyme activity was restored to the control levels. The in silico molecular docking data suggest that the coordination of the ions Pt(II), Pt(IV), Cu(II), Ag(I), and Au(III) with thiolates groups from C135 and C143 residues from the δ-ALA-D active site are crucial to the enzyme inhibition. The results indicate that a possible mechanism of inhibition of δ-ALA-D by these metals may involve the replacement of the Zn(II) from the active site and/or the cysteinyl residue oxidation.

Effects of antihistamines on the H295R steroidogenesis - Autocrine up-regulation following 3β-HSD inhibition

Millions of people of all ages suffer from allergies worldwide and as a consequence antihistamines are among the most commonly prescribed pharmaceuticals in the world. We investigated the disruptive effects of three antihistamines, promethazine (PMZ), cetirizine (CET) and fexofenadine (FEX) on the H295R steroidogenesis. A multi-steroid LC-MS/MS method was used to quantify 13 steroid hormones in the steroidogenesis. In addition, real-time RT-PCR was used to determine if exposure to antihistamines altered gene expression in the cell line. When exposing the H295R cells to PMZ and CET, significant increases in Δ⁵-steroids and significant decreases in Δ⁴-steroids were observed, indicating an inhibition of 3β-hydroxysteroid dehydrogenase (3β-HSD). A sequential decrease in corticosteroids, androgens and estrogens were also observed. Overall, FEX had no effect on the steroidogenesis even though minor effects were observed at the highest concentrations. Real-time RT-PCR showed that PMZ resulted in significant up-regulation of 3β-HSD and 17β-HSD, whereas CET only resulted in up-regulation of 3β-HSD. This indicated that the decrease in steroids downstream from 3β-HSD following PMZ and CT exposure induced a compensatory autocrine response in 3β-HSD gene expression. The effects on the steroidogenesis were observed at concentrations 30-50 times higher than the therapeutic plasma concentrations. However, antihistamines are lipophilic and may accumulate in adrenals and gonads. Thus, disruptive effects of PMZ and CET on human steroidogenesis cannot be excluded.

Two simple cleanup methods combined with LC-MS/MS for quantification of steroid hormones in in vivo and in vitro assays

Measuring both progestagens, androgens, corticosteroids as well as estrogens with a single method makes it possible to investigate the effects of endocrine-disrupting chemicals (EDCs) on the main pathways in the mammalian steroidogenesis. This paper presents two simple methods for the determination of the major steroid hormones in biological matrixes using liquid chromatography tandem mass spectrometry (LC-MS(2)). A novel method was developed for the determination of 14 steroids in the H295R in vitro assay without the need for solid phase extraction (SPE) purification prior to LC-MS(2) analysis. The in vitro assay was validated by exposing H295R cells to prochloraz for inhibiting steroid hormone secretion and by exposing cells to forskolin for inducing steroid hormone secretion. The developed method fulfills the recommendations for the H295R assay suggested by the OECD. Furthermore, a simple off-line SPE methodology was developed for the necessary clean-up of in vivo assays. Samples, such as gonad tissue, plasma and serum, are complex biological matrixes, and the SPE methodology was optimized to remove salts and proteins prior to elution of target analytes. At the same time, lipophilic compounds were retained on the SPE cartridge during elution. This, combined with the multi-steroid LC-MS(2) method, made it possible to determine 10 steroids in male Sprague-Dawley rat gonad tissue. Furthermore, it was possible to quantify 6 steroids in the plasma. In general, the observed concentration of steroid hormones in plasma, testes, and H295R cell medium corresponded well with previous studies. The off-line SPE method was validated using spiked charcoal-stripped serum. Method recovery, accuracy, precision and robustness were all good. Instrument sensitivity was in the range of 55-530 pg/mL (LLOQ).