Zearalenone metabolism in human placental subcellular organelles, JEG-3 cells, and recombinant CYP19A1

Associations between mycoestrogen exposure and sex steroid hormone concentrations in maternal serum and cord blood in the UPSIDE pregnancy cohort

Zearalenone (ZEN) is a fungal-derived toxin found in global food supplies including cereal grains and processed foods, impacting populations worldwide through diet. Because the chemical structure of ZEN and metabolites closely resembles 17β-estradiol (E2), they interact with estrogen receptors α/β earning their designation as 'mycoestrogens'. In animal models, gestational exposure to mycoestrogens disrupts estrogen activity and impairs fetal growth. Here, our objective was to evaluate relationships between mycoestrogen exposure and sex steroid hormone concentrations in maternal circulation and cord blood for the first time in humans. In each trimester, pregnant participants in the UPSIDE study (n = 297) provided urine for mycoestrogen analysis and serum for hormone analysis. At birth, placental mycoestrogens and cord steroids were measured. We fitted longitudinal models examining log-transformed mycoestrogen concentrations in relation to log-transformed hormones, adjusting for covariates. Secondarily, multivariable linear models examined associations at each time point (1st, 2nd, 3rd trimesters, delivery). We additionally considered effect modification by fetal sex. ZEN and its metabolite, α-zearalenol (α-ZOL), were detected in >93% and >75% of urine samples; >80% of placentas had detectable mycoestrogens. Longitudinal models from the full cohort exhibited few significant associations. In sex-stratified analyses, in pregnancies with male fetuses, estrone (E1) and free testosterone (fT) were inversely associated with ZEN (E1 %Δ: -6.68 95%CI: -12.34, -0.65; fT %Δ: -3.22 95%CI: -5.68, -0.70); while α-ZOL was positively associated with E2 (%Δ: 5.61 95%CI: -1.54, 9.85) in pregnancies with female fetuses. In analysis with cord hormones, urinary mycoestrogens were inversely associated with androstenedione (%Δ: 9.15 95%CI: 14.64, -3.30) in both sexes, and placental mycoestrogens were positively associated with cord fT (%Δ: 37.13, 95%CI: 4.86, 79.34) amongst male offspring. Findings support the hypothesis that mycoestrogens act as endocrine disruptors in humans, as in animal models and livestock. Additional work is needed to understand impacts on maternal and child health.

Evaluation of Lippia scaberrima Sond. and Aspalathus linearis (Burm.f.) R. Dahlgren extracts on human CYP enzymes and gold nanoparticle synthesis: implications for drug metabolism and cytotoxicity

BACKGROUND

Metabolism is an important component of the kinetic characteristics of herbal constituents, and it often determines the internal dose and concentration of these effective constituents at the target site. The metabolic profile of plant extracts and pure compounds need to be determined for any possible herb-drug metabolic interactions that might occur.

METHODS

Various concentrations of the essential oil of Lippia scaberrima, the ethanolic extract of Lippia scaberrima alone and their combinations with fermented and unfermented Aspalathus linearis extract were used to determine the inhibitory potential on placental, microsomal and recombinant human hepatic Cytochrome P450 enzymes. Furthermore, the study investigated the synthesis and characterization of gold nanoparticles from the ethanolic extract of Lippia scaberrima as a lead sample. Confirmation and characterization of the synthesized gold nanoparticles were conducted through various methods. Additionally, the cytotoxic properties of the ethanolic extract of Lippia scaberrima were compared with the gold nanoparticles synthesized from Lippia scaberrima using gum arabic as a capping agent.

RESULTS

All the samples showed varying levels of CYP inhibition. The most potent inhibition took place for CYP2C19 and CYP1B1 with 50% inhibitory concentration (IC50) values of less than 0.05 µg/L for the essential oil tested and IC50-values between 0.05 µg/L-1 µg/L for all the other combinations and extracts tested, respectively. For both CYP1A2 and CYP2D6 the IC50-values for the essential oil, the extracts and combinations were found in the range of 1 - 10 µg/L. The majority of the IC50 values found were higher than 10 µg/L and, therefore, were found to have no inhibition against the CYP enzymes tested.

CONCLUSION

Therefore, the essential oil of Lippia scaberrima, the ethanolic extract of Lippia scaberrima alone and their combinations with Aspalathus linearis do not possess any clinically significant CYP interaction potential and may be further investigated for their adjuvant potential for use in the tuberculosis treatment regimen. Furthermore, it was shown that the cytotoxic potential of the Lippia scaberrima gold nanoparticles was reduced by twofold when compared to the ethanolic extract of Lippia scaberrima.

Optimized extraction and analysis methods using liquid chromatography-tandem mass spectrometry for zearalenone and metabolites in human placental tissue

Zearalenone and its metabolites, a group of endocrine disrupting mycotoxins, have been linked to adverse reproductive health effects. They cross the placental barrier, potentially reaching the fetus. In this study, we adapted and optimized our protocol previously used for urine, to measure these mycotoxins in human placentas. We combined a supported liquid extraction step using Chem Elut cartridges with solid phase extraction on Discovery® DSC-NH2 tubes. The optimized extraction efficiencies were between 68 and 80% for all metabolites. Analysis was performed by UHPLC-HRMS using a Betasil™ Phenyl-Hexyl column eluted with a gradient of acetonitrile-methanol-water. The chromatography method separated all analytes in under 15 min. Validation experiments confirmed the method's sensitivity, with LODs ranging from 0.0055 to 0.011 pg/mg tissue. The method was linear over a range of 0.0025-1.5 pg/mg tissue with R2 values ≥ 0.994. Precision and accuracy calculations ranged from 4.7-7.9% and 0.6-6.7% respectively. The method was then successfully applied to a subset of placenta samples (n = 25) collected from an ongoing prospective birth cohort. Interestingly, 92% of the samples contained at least one measurable zearalenone metabolite, providing initial indication of potentially widespread exposure during pregnancy.

Zearalenone induces apoptosis and autophagy by regulating endoplasmic reticulum stress signalling in porcine trophectoderm cells

Zearalenone (ZEA), a mycotoxin produced mainly by fungi belonging to Fusarium species in foods and feeds, causes a serious hazard to humans and animals. Numerous studies have revealed that ingesting ZEA can disrupt the reproductive function and impair the reproductive process in animals. This experiment was to investigate the toxicological effect and the mechanism of ZEA exposure on reproduction in pigs during early stages of pregnancy. In the present study, we treated with 0 to 80 μmol/L ZEA for 12 or 24 h in trophoblast ectoderm (pTr) cells. The results showed that ZEA had significantly decreased cell proliferation (P < 0.05), which was accompanied by DNA damage-related cell cycle arrest at G2/M phase, activation of the apoptosis and endoplasmic reticulum (ER) stress, as well as impairment of barrier function (P < 0.05). Western blot analysis and transmission electron microscopy (TEM) showed that exposure to ZEA can activation of autophagy in pTr cells. Importantly, pretreatment with chloroquine (CQ) or 3-methyladenine (3-MA) led to increased apoptosis in pTr cells. Interestingly, pTr cells pretreated with 4-phenylbutyric acid (4-PBA), an inhibitor of ER stress, resulted in reduced cell death in pTr cells, indicating a critical role for ER stress in the activation of autophagy. In conclusion, these results reveal that ZEA-triggered ER stress is critical for the cell fate decision of pTr cells during early porcine embryonic development. Application of small molecules with ability of blocking ER stress might be therapeutic option to reduce the deleterious effect of ZEA in pregnant animals.

Elucidation of xenoestrogen metabolism by non-targeted, stable isotope-assisted mass spectrometry in breast cancer cells

Environmental exposure to xenoestrogens, i.e., chemicals that imitate the hormone 17β-estradiol, has the potential to influence hormone homeostasis and action. Detailed knowledge of xenobiotic biotransformation processes in cell models is key when transferring knowledge learned from in vitro models to in vivo relevance. This study elucidated the metabolism of two naturally-occurring phyto- and mycoestrogens; namely genistein and zearalenone, in an estrogen receptor positive breast cancer cell line (MCF-7) with the aid of stable isotope-assisted metabolomics and the bioinformatic tool MetExtract II. Metabolism was studied in a time course experiment after 2 h, 6 h and 24 h incubation. Twelve and six biotransformation products of zearalenone and genistein were detected, respectively, clearly demonstrating the abundant xenobiotic biotransformation capability of the cells. Zearalenone underwent extensive phase-I metabolism resulting in α-zearalenol (α-ZEL), a molecule known to possess a significantly higher estrogenicity, and several phase-II metabolites (sulfo- and glycoconjugates) of the native compound and the major phase I metabolite α-ZEL. Moreover, potential adducts of zearalenone with a vitamin and several hydroxylated metabolites were annotated. Genistein metabolism resulted in sulfation, combined sulfation and hydroxylation, acetylation, glucuronidation and unexpectedly adduct formation with pentose- and hexose sugars. Kinetics of metabolite formation and subsequent excretion into the extracellular medium revealed a time-dependent increase in most biotransformation products. The untargeted elucidation of biotransformation products formed during cell culture experiments enables an improved and more meaningful interpretation of toxicological assays and has the potential to identify unexpected or unknown metabolites.

Immunotoxicity and uterine transcriptome analysis of the effect of zearalenone (ZEA) in sows during the embryo attachment period

Zearalenone is a mycotoxin and a pollutant that is commonly found in crops. Once ingested, ZEA can cause disturbances in the immune system and produce immunotoxicity. However, there is little research on the effect of ZEA exposure on the relationship between immune regulation and embryo implantation in the uteri of sows. Embryo implantation relies upon the fact that the relationship between the maternal and fetal immune systems is balanced. This balance is provided by the joint regulation of immune organs, cytokines, and uterine immunity. In this study, we investigated 20 sows with an initial weight of 100.00 ± 5.00 kg and 200 days in age. The sows were fed with diets containing ZEA at concentrations of 0 mg/kg, 1 mg/kg, 2 mg/kg, and 10 mg/kg, respectively, from 8 to 14 days of gestation. We studied immunotoxicity and the uterine transcriptomics associated with the effect of ZEA in sows during embryo attachment. Following ZEA treatment, serum biochemical analysis and RT-qPCR were used to detect the concentration and mRNA expression levels of immunoglobulin IgA, IgG, and IgM, in the serum and spleen, respectively. The same analysis was carried out for a range of cytokines in the serum and spleen: IL-1, IL-2, IL-6, IL-10, and TNF. Uterine transcriptome analysis revealed 75, 215, and 81 genes that were differentially expressed in the 0 mg/kg vs 1 mg/kg treatment, 0 mg/kg vs 10 mg/kg treatment, and 1 mg/kg vs 10 mg/kg treatment, respectively. GO terms analysis showed that the up-regulated genes related to the immune system were highly expressed. KEGG pathway analysis further revealed the importance of several metabolic pathways, including drug metabolism-cytochrome P450, the cytokine-cytokine receptor interaction pathway, and calcium signaling pathways. The differentially expressed genes were confirmed by quantitative real-time PCR. These findings expand our understanding of the gene expression profiles and signaling pathways associated with the immune response to ZEA exposure in sows during the embryo implantation window. This study provides valuable information for clarifying the molecular mechanism of ZEA's immunotoxicity to early pregnant sows in the future.

Transfer and Metabolism of the Xenoestrogen Zearalenone in Human Perfused Placenta

BACKGROUND

Pregnancy is a sensitive condition during which adverse environmental exposures should be monitored thoroughly and minimized whenever possible. In particular, the hormone balance during gestation is delicate, and disturbance may cause acute or chronic long-term health effects. A potential endocrine disruption may be provoked by in utero exposure to xenoestrogens mimicking endogenous estrogens. The mycoestrogen zearalenone (ZEN), a toxic fungal secondary metabolite and mycotoxin found frequently in food and feed, constitutes a prominent example.

OBJECTIVES

We performed a comprehensive assessment of the transfer as well as phase I and phase II metabolism of ZEN at the human placental barrier.

METHODS

Human placentas were perfused with 1μM (318μg/L) ZEN for 6 h. Samples from the maternal and fetal compartment, placental tissue, and fetal plasma were analyzed by a highly sensitive UHPLC-MS/MS assay to detect ZEN as well as nine key metabolites (α-zearalenol, β-zearalenol, zearalanone, α-zearalanol, β-zearalanol, ZEN-14-glucuronide, α-zearalenol-14-glucuronide, β-zearalenol-14-glucuronide, ZEN-14-sulfate).

RESULTS

The model revealed a fast maternofetal transfer of ZEN across the human placental barrier. We also unraveled phase I and phase II metabolism of the parent toxin ZEN into the approximately 70-times more estrogenic α-zearalenol and the less active ZEN-14-sulfate conjugate, which are effectively released into the maternal and fetal circulation in considerable amounts.

CONCLUSIONS

Our findings suggest that exposure to ZEN (such as through consumption of ZEN-contaminated cereal-based products) during pregnancy may result in in utero exposure of the fetus, not only to ZEN but also some of its highly estrogenically active metabolites. In the light of the known affinity of ZEN and potentially co-occurring xenoestrogens to the estrogen receptor, and our results demonstrating placental transfer of ZEN and its metabolites in an ex vivo model, we recommend further research and more comprehensive assessment of gestational exposures in women. https://doi.org/10.1289/EHP4860.

In Vitro Human Metabolism and Inhibition Potency of Verbascoside for CYP Enzymes

Verbascoside is found in many medicinal plant families such as Verbenaceae. Important biological activities have been ascribed to verbascoside. Investigated in this study is the potential of verbascoside as an adjuvant during tuberculosis treatment. The present study reports on the in vitro metabolism in human hepatic microsomes and cytosol incubations as well as the presence and quantity of verbascoside within Lippia scaberrima. Additionally, studied are the inhibitory properties on human hepatic CYP enzymes together with antioxidant and cytotoxic properties. The results yielded no metabolites in the hydrolysis or cytochrome P450 (CYP) oxidation incubations. However, five different methylated conjugates of verbascoside could be found in S-adenosylmethionine incubation, three different sulphate conjugates with 3'-phosphoadenosine 5'-phosphosulfate (PAPS) incubation with human liver samples, and very low levels of glucuronide metabolites after incubation with recombinant human uridine 5'-diphospho-glucuronosyltransferase (UGT) 1A7, UGT1A8, and UGT1A10. Additionally, verbascoside showed weak inhibitory potency against CYP1A2 and CYP1B1 with IC50 values of 83 µM and 86 µM, respectively. Potent antioxidant and low cytotoxic potential were observed. Based on these data, verbascoside does not possess any clinically relevant CYP-mediated interaction potential, but it has effective biological activity. Therefore, verbascoside could be considered as a lead compound for further drug development and as an adjuvant during tuberculosis treatment.

Zearalenone and its metabolites: Effect on human health, metabolism and neutralisation methods

Mycotoxins are natural compounds produced as secondary metabolites by mold fungi belonging mainly to the Fusarium family, commonly found on plants such as corn or small grains in the temperate climate zone. One of these mycotoxins is zearalenone, which is classified as a xenoestrogen, an exogenous compound which resembles the structure of naturally occurring estrogens with its chemical structure. This property of zearalenone determines its ability to bind to estrogen receptors of cell and its bioaccumulation. This leads to disorders of the hormonal balance of the body, which in consequence may lead to numerous diseases of reproductive system such as prostate, ovarian, cervical or breast cancers. High risk posed by long-term exposure to contaminated food forces the modern science to develop and implement effective methods of zearalenone neutralisation. This work is a review of current state of knowledge on toxic effects of zearalenone, its metabolism in biological systems and proposed methods of its neutralisation.

Dietary exposure to mycotoxin zearalenone (ZEA) during post-implantation adversely affects placental development in mice

Zearalenone (ZEA) is a common food contaminant (ppb-ppm) derived from Fusarium fungi. With its estrogenicity and potential chronic exposure, ZEA poses a risk to pregnancy. Our previous studies implied post-implantational lethality by ZEA. Since a functional placenta is essential for fetal development and survival, it was hypothesized that ZEA may have adverse effects on placental development leading to post-implantational lethality. Exposure of young mice to 0, 0.8, 4, 10, and 40 ppm ZEA diets from gestation day 5.5 (D5.5) to D13.5 led to increased resorption of implantation sites, increased placental hemorrhage, decreased placental and fetal weights, proportionally reduced placental layers, and disorganized placental labyrinth vascular spaces in the 40 ppm ZEA group, as well as lipid accumulation in the labyrinth layer of all four ZEA treatment groups examined on D13.5. These data demonstrate adverse effects of ZEA on placental development.

Gestational bisphenol S impairs placental endocrine function and the fusogenic trophoblast signaling pathway

Exposure to bisphenolic chemicals during pregnancy occurs in > 90% of pregnancies. Bisphenolic compounds can cross the placental barrier reaching fetal circulation. However, the effects of emerging bisphenolic compounds, such as bisphenol S (BPS), on placental function remain untested. The aim was to determine if bisphenol A (BPA) or BPS, at an environmentally relevant dose, impairs placental function. Pregnant sheep were randomly distributed into three treatment groups (n = 7-8/group): control, BPA, and BPS. All animals received daily injections of corn oil (control), BPA, or BPS (0.5 mg/kg; s.c.; internal fetal doses were ~ 2.6 ng/mL unconjugated BPA and ~ 7.7 ng/mL of BPS) from gestational day 30-100. After a 20-day washout period, placentas were weighed and placentomes collected. Placental endocrine function was assessed on biweekly maternal blood samples. Gestational exposure to BPS, but not BPA, reduced maternal circulating pregnancy-associated glycoproteins without change in placental weight or placental stereology. BPS-exposed placentas had 50% lower e-cadherin protein expression, ~ 20% fewer binucleate cells, and ~ threefold higher glial cell missing-1 protein expression. BPA placentas were not affected highlighting the intrinsic differences among bisphenolic chemicals. This is the first study to demonstrate that gestational BPS can result in placental endocrine dysfunction and points to a dysregulation in the fusogenic trophoblast signaling pathway.

Zearalenone as an endocrine disruptor in humans

Zearalenone (ZEA), a fungal mycotoxin, is present in a wide range of human foods. Many animal studies have found ZEA to possess a disruptive effect on the hormonal balance, mainly due to its similarity to naturally-occurring estrogens. With increasing consciousness of the adverse effects of endocrine disruptors on human health, it is becoming more important to monitor ZEA concentrations in food and identify its potential effects on human health. Based on a review of recent studies on animal models and molecular pathways in which ZEA is reported to have an influence on humans, we postulate that ZEA might act as an endocrine disruptor in humans in a similar way to animals. Moreover, its endocrine-disrupting effect might be also a causative factor in carcinogenesis. This review article summarizes the latest knowledge about the influence of ZEA on the human hormonal balance.