Assessing pregnancy risks of azole antifungals using a high throughput aromatase inhibition assay

Association between Environmental Exposure to Multiclass Organic Pollutants and Sex Steroid Hormone Levels in Women of Reproductive Age

Organic pollutant exposure may alter sex steroid hormone levels in both animals and humans, but studies on mixture effects have been lacking and mainly limited to persistent organic pollutants, with few hormones being investigated. Moreover, measurements from a single blood or urine sample may not be able to reflect long-term status. Using hair analysis, here, we evaluated the relationship between multiclass organic pollutants and sex steroid hormones in 196 healthy Chinese women aged 25-45 years. Associations with nine sex steroid hormones, including progesterone, androstenedione (AD), testosterone (T), estrone (E1), and 17β-estradiol (E2), and eight related hormone ratios were explored on 54 pollutants from polychlorinated biphenyl (PCB), pesticide, and bisphenol families using stability-based Lasso regression analysis. Our results showed that each hormone was associated with a mixture of at least 10 examined pollutants. In particular, hair E2 concentration was associated with 19 pollutants, including γ-hexachlorocyclohexane, propoxur, permethrin, fipronil, mecoprop, prochloraz, and carbendazim. There were also associations between pollutants and hormone ratios, with pentachlorophenol, dimethylthiophosphate, 3-phenoxybenzoic acid, and flusilazole being related to both E1/AD and E2/T ratios. Our results suggest that exposure to background levels of pesticides PCB180 and bisphenol S may affect sex steroid hormone homeostasis among women of reproductive age.

Azole Fungicides and Their Endocrine Disrupting Properties: Perspectives on Sex Hormone-Dependent Reproductive Development

Azoles are antifungal agents used in both agriculture and medicine. They typically target the CYP51 enzyme in fungi and, by so doing, disrupt cell membrane integrity. However, azoles can also target various CYP enzymes in mammals, including humans, which can disrupt hormone synthesis and signaling. For instance, several azoles can inhibit enzymes of the steroidogenic pathway and disrupt steroid hormone biosynthesis. This is of particular concern during pregnancy, since sex hormones are integral to reproductive development. In other words, exposure to azole fungicides during fetal life can potentially lead to reproductive disease in the offspring. In addition, some azoles can act as androgen receptor antagonists, which can further add to the disrupting potential following exposure. When used as pharmaceuticals, systemic concentrations of the azole compounds can become significant as combatting fungal infections can be very challenging and require prolonged exposure to high doses. Although most medicinal azoles are tightly regulated and used as prescription drugs after consultations with medical professionals, some are sold as over-the-counter drugs. In this review, we discuss various azole fungicides known to disrupt steroid sex hormone biosynthesis or action with a focus on what potential consequences exposure during pregnancy can have on the life-long reproductive health of the offspring.

Human-relevant concentrations of the antifungal drug clotrimazole disrupt maternal and fetal steroid hormone profiles in rats

Clotrimazole is a non-prescription and broad-spectrum antifungal drug sold under brand names such as Canesten® and Lotrimin®. It is used to treat different types of fungal infections, from oral thrush to athlete's foot and vaginal mycosis. The level of exposure to clotrimazole is uncertain, as the exact usage amongst self-medicating patients is unclear. Recent studies have raised potential concern about the unsupervised use of clotrimazole during pregnancy, especially since it is a potent inhibitor of CYP enzymes of the steroidogenesis pathway. To address some of these concerns, we have assessed the effects of intrauterine exposure to clotrimazole on developing rat fetuses. By exposing pregnant rats to clotrimazole 25 or 75 mg/kg bw/day during gestation days 7-21, we obtained internal fetal concentrations close to those observed in humans. These in vivo data are in strong agreement with our physiologically-based pharmacokinetic (PBK)-modelled levels. At these doses, we observed no obvious morphological changes to the reproductive system, nor shorter male anogenital distance; a well-established morphometric marker for anti-androgenic effects in male offspring. However, steroid hormone profiles were significantly affected in both maternal and fetal plasma, in particular pronounced suppression of estrogens was seen. In fetal testes, marked up-concentration of hydroxyprogesterone was observed, which indicates a specific action on steroidogenesis. Since systemic clotrimazole is rapidly metabolized in humans, relevant exposure levels may not in itself cause adverse changes to the reproductive systems. Its capacity to significantly alter steroid hormone concentrations, however, suggests that clotrimazole should be used with caution during pregnancy.

Synthesis, Optimization, Antifungal Activity, Selectivity, and CYP51 Binding of New 2-Aryl-3-azolyl-1-indolyl-propan-2-ols

A series of 2-aryl-3-azolyl-1-indolyl-propan-2-ols was designed as new analogs of fluconazole (FLC) by replacing one of its two triazole moieties by an indole scaffold. Two different chemical approaches were then developed. The first one, in seven steps, involved the synthesis of the key intermediate 1-(1H-benzotriazol-1-yl)methyl-1H-indole and the final opening of oxiranes by imidazole or 1H-1,2,4-triazole. The second route allowed access to the target compounds in only three steps, this time with the ring opening by indole and analogs. Twenty azole derivatives were tested against Candida albicans and other Candida species. The enantiomers of the best anti-Candida compound, 2-(2,4-dichlorophenyl)-3-(1H-indol-1-yl)-1-(1H-1,2,4-triazol-1-yl)-propan-2-ol (8g), were analyzed by X-ray diffraction to determine their absolute configuration. The (−)-8g enantiomer (Minimum inhibitory concentration (MIC) = IC₈₀ = 0.000256 µg/mL on C. albicans CA98001) was found with the S-absolute configuration. In contrast the (+)-8g enantiomer was found with the R-absolute configuration (MIC = 0.023 µg/mL on C. albicans CA98001). By comparison, the MIC value for FLC was determined as 0.020 µg/mL for the same clinical isolate. Additionally, molecular docking calculations and molecular dynamics simulations were carried out using a crystal structure of Candida albicans lanosterol 14α-demethylase (CaCYP51). The (−)-(S)-8g enantiomer aligned with the positioning of posaconazole within both the heme and access channel binding sites, which was consistent with its biological results. All target compounds have been also studied against human fetal lung fibroblast (MRC-5) cells. Finally, the selectivity of four compounds on a panel of human P450-dependent enzymes (CYP19, CYP17, CYP26A1, CYP11B1, and CYP11B2) was investigated.

The novel fungal CYP51 inhibitor VT-1598 is efficacious alone and in combination with liposomal amphotericin B in a murine model of cryptococcal meningitis

Objectives

Annual global deaths from cryptococcal meningitis (CM) are estimated at 180 000 and mortality is as high as 30%, even with optimal therapy. VT-1598 is a novel fungal CYP51 inhibitor with potent intrinsic antifungal activity against Cryptococcus. We report here VT-1598's in vivo antifungal activity in a murine model of CM.

Methods

Single-dose plasma and brain pharmacokinetics in mice and MIC for Cryptococcus neoformans H99 were determined prior to efficacy studies. Short-course monotherapy and combination doses were explored with the endpoint of brain fungal burden. A survival study was also conducted using monotherapy treatment with fungal burden measured after a 6 day drug washout.

Results

Oral doses of VT-1598 had good plasma and brain exposure and resulted in significant (P < 0.0001) and dose-dependent reductions in brain fungal burden, reaching a 6 log10 reduction. Unlike either positive drug control (fluconazole or liposomal amphotericin B), both mid and high doses of VT-1598 reduced fungal burden to below levels measured at the start of treatment. When VT-1598 was dosed in the survival study, no VT-1598-treated animal succumbed to the infection. Whereas fluconazole showed a 2.5 log10 increase in fungal burden after the 6 day washout, the VT-1598 mid- and high-dose animals showed almost no regrowth (<0.5 log10). In a separate fungal burden study using suboptimal doses of VT-1598 and liposomal amphotericin B to probe for combination effects, each combination had a positive effect relative to corresponding monotherapies.

Conclusions

These pre-clinical in vivo data strongly support clinical investigation of VT-1598 as a novel therapy for this lethal infection.

Topical antiviral and antifungal medications in pregnancy: a review of safety profiles

Medications should be employed with caution in women of childbearing age who are pregnant or considering pregnancy. Compared to oral or parenteral agents, topical medications have limited systemic absorption and are deemed safer. However, their safety profile must be assessed cautiously due to the limited available data. In this article, we aggregate human and animal studies to provide recommendations on utilizing topical antiviral and antifungal medications in pregnancy. For antiviral medications, acyclovir and trichloroacetic acid are safe to use in pregnancy. Docosanol, imiquimod and penciclovir are likely safe, but should be utilized as second-line agents. Podofilox and podophyllin resin should be avoided. For antifungal medications, clotrimazole, miconazole and nystatin are considered first-line agents. Butenafine, ciclopirox, naftifine, oxiconazole and terbinafine may be utilized after the above agents. Econazole should be avoided during the first trimester and used sparingly during 2nd and 3rd trimester. Ketoconazole and selenium sulphide are likely safe, but should be employed in limited areas for brief periods.

Impact on CYP19A1 activity by mutations in NADPH cytochrome P450 oxidoreductase

Cytochrome P450 aromatase (CYP19A1), in human placenta metabolizes androgens to estrogens and uses reduced nicotinamide adenine dinucleotide phosphate through cytochrome P450 oxidoreductase (POR) for the energy requirements of its metabolic activities. Mutations in the human POR lead to congenital adrenal hyperplasia due to loss of activities of several steroid metabolizing enzymatic reactions conducted by the cytochrome P450 proteins located in the endoplasmic reticulum. Effect of POR mutations on different P450 activities depend on individual partner proteins. In this report we have studied the impact of mutations found in the POR on the enzymatic activity of CYP19A1. We expressed wild type as well mutant human POR proteins in bacteria and purified the recombinant proteins, which were then used in an in vitro reconstitution system in combination with CYP19A1 and lipids for enzymatic analysis. We found that several mutations as well as polymorphisms in human POR can cause reduction of CYP19A1 activity. This would affect metabolism of estrogens in people with variations of POR allele. The POR mutants Y181D and R616X were found to have no activity in supporting CYP19A1 reactions. The POR mutations Y607C and delF646 showed a loss of 60-90% activity and two polymorphic forms of POR, R316W and G413S showed similar to WT activity. One POR variant, Q153R had almost double the activity of WT. Loss of CYP19A1 activity may contribute to disordered steroidogenesis in female patients with POR mutations as well as in mothers with POR variants carrying a male child.

[The screening of the inhibitors of the human cytochrome P450(51) (CYP51A1): the plant and animal structural lanosterol's analogs]

The cholesterol biosynthesis regulation is the important part of the hypercholesterolemia diseases therapy. The inhibition of the post-squalene cholesterol biosynthesis steps provide the alternative to classic statin therapy. Sterol-14a-demethylase (CYP51) is one of the hypothetical targets for it. In this work the screening of the ability to interact with human CYP51 (CYP51A1) for the nature low-weight compounds with steroid-like scaffold were performed by integration of the surface plasmon resonance biosensor and spectral titration methods. The results of the selection were 4 compounds (betulafolientriol, holothurin A, teasaponin, capsicoside A) witch had high affinity to the CYP51A1 active site. These data extend the range of compounds which may be used as specific inhibitors of CYP51 and give the permission to suggest the dynamic of the enzyme.

The clinical candidate VT-1161 is a highly potent inhibitor of Candida albicans CYP51 but fails to bind the human enzyme

The binding and cytochrome P45051 (CYP51) inhibition properties of a novel antifungal compound, VT-1161, against purified recombinant Candida albicans CYP51 (ERG11) and Homo sapiens CYP51 were compared with those of clotrimazole, fluconazole, itraconazole, and voriconazole. VT-1161 produced a type II binding spectrum with Candida albicans CYP51, characteristic of heme iron coordination. The binding affinity of VT-1161 for Candida albicans CYP51 was high (dissociation constant [Kd], ≤ 39 nM) and similar to that of the pharmaceutical azole antifungals (Kd, ≤ 50 nM). In stark contrast, VT-1161 at concentrations up to 86 μM did not perturb the spectrum of recombinant human CYP51, whereas all the pharmaceutical azoles bound to human CYP51. In reconstitution assays, VT-1161 inhibited Candida albicans CYP51 activity in a tight-binding fashion with a potency similar to that of the pharmaceutical azoles but failed to inhibit the human enzyme at the highest concentration tested (50 μM). In addition, VT-1161 (MIC = 0.002 μg ml(-1)) had a more pronounced fungal sterol disruption profile (increased levels of methylated sterols and decreased levels of ergosterol) than the known CYP51 inhibitor voriconazole (MIC = 0.004 μg ml(-1)). Furthermore, VT-1161 weakly inhibited human CYP2C9, CYP2C19, and CYP3A4, suggesting a low drug-drug interaction potential. In summary, VT-1161 potently inhibited Candida albicans CYP51 and culture growth but did not inhibit human CYP51, demonstrating a >2,000-fold selectivity. This degree of potency and selectivity strongly supports the potential utility of VT-1161 in the treatment of Candida infections.

Treatment of common skin infections and infestations during pregnancy

In the absence of systematic studies in pregnant and lactating women, recommendations for the treatment of infections during pregnancy are based on animal studies, accumulated evidence from clinical use and case reports, as well as published consensus statements and expert opinion. This article examines the evidence basis for the treatment of common cutaneous infections in women who are pregnant or breast-feeding.

A comparative study for the evaluation of two doses of ellagic acid on hepatic drug metabolizing and antioxidant enzymes in the rat

The present study was designed to evaluate different doses of ellagic acid (EA) in vivo in rats for its potential to modulate hepatic phases I, II, and antioxidant enzymes. EA (10 or 30 mg/kg/day, intragastrically) was administered for 14 consecutive days, and activity, protein, and mRNA levels were determined. Although the cytochrome P450 (CYP) 2B and CYP2E enzyme activities were decreased significantly, the activities of all other enzymes were unchanged with the 10 mg/kg/day EA. In addition, western-blot and qRT-PCR results clearly corroborated the above enzyme expressions. On the other hand, while the NAD(P)H:quinone oxidoreductase 1 (NQO1), catalase (CAT), glutathione peroxidase (GPX), and glutathione S-transferase (GST) activities were increased significantly, CYP1A, 2B, 2C, 2E, and 19 enzyme activities were reduced significantly with 30 mg/kg/day EA. In addition, CYP2B, 2C6, 2E1, and 19 protein and mRNA levels were substantially decreased by the 30 mg/kg/day dose of EA, but the CYP1A protein, and mRNA levels were not changed. CYP3A enzyme activity, protein and mRNA levels were not altered by neither 10 nor 30 mg/kg/day ellagic acid. These results indicate that EA exerts a dose-dependent impact on the metabolism of chemical carcinogens and drugs by affecting the enzymes involved in xenobiotics activation/detoxification and antioxidant pathways.

NADPH P450 oxidoreductase: structure, function, and pathology of diseases

Cytochrome P450 oxidoreductase (POR) is an enzyme that is essential for multiple metabolic processes, chiefly among them are reactions catalyzed by cytochrome P450 proteins for metabolism of steroid hormones, drugs and xenobiotics. Mutations in POR cause a complex set of disorders that often resemble defects in steroid metabolizing enzymes 17α-hydroxylase, 21-hydroxylase and aromatase. Since our initial reports of POR mutations in 2004, more than 200 different mutations and polymorphisms in POR gene have been identified. Several missense variations in POR have been tested for their effect on activities of multiple steroid and drug metabolizing P450 proteins. Mutations in POR may have variable effects on different P450 partner proteins depending on the location of the mutation. The POR mutations that disrupt the binding of co-factors have negative impact on all partner proteins, while mutations causing subtle structural changes may lead to altered interaction with specific partner proteins and the overall effect may be different for each partner. This review summarizes the recent discoveries related to mutations and polymorphisms in POR and discusses these mutations in the context of historical developments in the discovery and characterization of POR as an electron transfer protein. The review is focused on the structural, enzymatic and clinical implications of the mutations linked to newly identified disorders in humans, now categorized as POR deficiency.

Association of high-dose bifonazole administration during early pregnancy and severe limb reduction defects in the newborn

BACKGROUND

Neonatal limb reduction defects may be caused by exposure to an external agent. The azole derivatives are used in the treatment of systemic and dermal mycoses. Their relative teratogenic risk is still controversial.

CASES

We describe two newborns with severe limb defects who were exposed to high doses of oral (an unacceptable route) and/or intravaginal bifonazole during the entire first trimester of pregnancy.

CONCLUSION

Although only two cases are insufficient to establish a relationship, our data suggest that maternal intake of bifonazole in early pregnancy poses a risk of morphogenic malformations. The literature suggests several possible mechanisms.

Restoration of mutant cytochrome P450 reductase activity by external flavin

Cytochrome P450 oxidoreductase (POR) supplies electrons from NADPH to steroid and drug metabolizing reactions catalyzed by the cytochrome P450s located in endoplasmic reticulum. Mutations in human POR cause a wide spectrum of disease ranging from disordered steroidogenesis to sexual differentiation. Previously we and others have shown that POR mutations can lead to reduced activities of steroidogenic P450s CYP17A1, CYP19A1 and CYP21A1. Here we are reporting that mutations in the FMN binding domain of POR may reduce CYP3A4 activity, potentially influencing drug and steroid metabolism; and the loss of CYP3A4 activity may be correlated to the reduction of cytochrome b(5) by POR. Computational molecular docking experiments with a FMN free structural model of POR revealed that an external FMN could be docked in close proximity to the FAD moiety and receive electrons donated by NADPH. Using FMN supplemented assays we have demonstrated restoration of the defective POR activity in vitro.

Fabrication of modified transport fluconazole transdermal spray containing ethyl cellulose and Eudragit RS100 as film formers

The present investigation was undertaken to fabricate modified transport fluconazole transdermal spray using ethyl cellulose and Eudragit RS100 as film-forming polymers. Eudragit RS100 (X(1)) and ethyl cellulose (X(2)) were selected as independent variables in 3(2) full factorial design, whereas drug transport in first hour (Y (1)) and the time required for 50% drug transport (Y(2)) were selected as dependent variables. Eutectic blend of camphor and menthol was used as permeation enhancer cum solvent for film-forming polymers. The pH, viscosity, volume of solution delivered upon each actuation, spray angle, ex-in vivo physical evaluation and in vitro drug transport of the formulated products were evaluated. The optimized batch B16 containing 5.25% w/w ethyl cellulose and 10.6% w/w Eudragit RS100 was formulated by overlapping the contour plots of Y(1) and Y(2). The pH, viscosity, volume of solution sprayed upon each actuation and spray angle of the batch B16 was 6.3, 52.9 cPs, 0.24 ml and 82.6 degrees respectively. The film of optimized batch was flexible and dermal-adhesive. The responses Y(1) and Y(2) of batch B16 were 7.91 microg/ml and 347 min respectively. The kinetics of drug transport was best explained by the Korsmeyer and Peppas model. The eutectic mixture consisting of equal parts of camphor and menthol showed improved drug permeation through shed snake skin. Short-term stability study demonstrated insignificant changes in performance characteristics.

Aromatase inhibition by bioavailable methylated flavones

Previous studies have shown chrysin, 7-hydroxyflavone and 7,4'-dihydroxyflavone to be the most potent flavonoid inhibitors of aromatase. However, very poor oral bioavailability is a major limitation for the successful use of dietary flavonoids as chemopreventive agents. We have recently shown that methylated flavones, including 5,7-dimethoxyflavone, 7-methoxyflavone and 7,4'-dimethoxyflavone, are much more resistant to metabolism than their unmethylated analogs and have much higher intestinal absorption. In this study, we examined these fully methylated flavones as potential aromatase inhibitors for the prevention and/or treatment of hormone-dependent cancers. Whereas 5,7-dimethoxyflavone had poor effect compared to its unmethylated analog chrysin, 7-methoxyflavone and 7,4'-dimethoxyflavone were almost equipotent to their unmethylated analogs with IC(50) values of 2-9 microM. Thus, some fully methylated flavones appear to have great potential as cancer chemopreventive/chemotherapeutic agents.

Inhibition of human CYP19 by azoles used as antifungal agents and aromatase inhibitors, using a new LC–MS/MS method for the analysis of estradiol product formation

Azoles are used as fungicides in agriculture or antifungal drugs in medicine. Their therapeutic activity is based on the inhibition of fungal lanosterol-14alpha-demethylase (CYP51). Azoles are also used for the treatment of estrogen-dependent diseases, e.g. in breast cancer therapy. Inhibition of CYP19 (aromatase) is the working principle for tumor therapy, but is an unwanted side effect of azoles used as fungicides or antifungal drugs. The inhibition of recombinant human CYP19 by 21 azoles in use for the three different purposes was investigated using the natural substrate testosterone. Estradiol product formation was measured by a newly developed and fully validated analytical method based on liquid chromatography-tandem mass spectrometry utilizing photospray ionization (APPI). Potency of enzyme inhibition was expressed in terms of IC50 concentrations. The two cytostatic drugs fadrozole and letrozole were the most potent inhibitors. However, azoles used as fungicides, e.g. prochloraz, or as antifungal drugs, e.g. bifonazole, were almost as potent inhibitors of aromatase as the drugs used in tumor therapy. Comparison of plasma concentrations that may be reached in antifungal therapy do not allow for large safety factors for bifonazole and miconazole. The IC50 values were compared to data obtained with other substrates, such as the pseudo-substrate dibenzylfluorescein (DBF). A high correlation was found, indicating that the fluorescence assay with DBF can well be used for potency ranking and screening of chemicals for aromatase inhibition. The data for antifungal drugs show that side effects on steroid hormone synthesis in humans due to inhibition of aromatase should be considered.

Comparative assessment of the inhibition of recombinant human CYP19 (aromatase) by azoles used in agriculture and as drugs for humans

Azoles (imidazoles and triazoles) are used as antifungal agents in agriculture and in medicine, and also for antiestrogen therapy, e.g., for breast cancer treatment. Antifungal activity is based on inhibition of fungal CYP51 (lanosterol 14alpha-demethylase), and estrogen biosynthesis reduction is due to azole inhibition of CYP19 (aromatase). Inhibition of aromatase by antifungal agents is usually an unwanted side effect and may cause endocrine disruption. A fluorimetric assay based on human recombinant CYP19 enzyme with dibenzylfluorescein as a substrate was used to compare the inhibitory potency of 22 azole compounds. Dose responses were established and duplicate datasets were analyzed with a nonlinear mixed-effects model with cumulative normal distribution for the logarithm of concentration. IC50 values (50% inhibitory concentration) of 13 fungicides used in agriculture ranged more than 700-fold, starting from 0.047 microM. The potency of seven human drugs spanned more than 7000-fold, starting from 0.019 microM. Most potent fungicides included prochloraz, flusilazole, and imazalil, and most potent medicinal antifungals were bifonazole, miconazole, and clotrimazole. These in vitro data indicate that the top-ranking azoles used as antifungal agents or drugs are as potent inhibitors of aromatase as are antiestrogen therapeutics used to treat breast cancer. These putative effects of azole agents and drugs on steroid biosynthesis and sex hormone balance should be considered when used in human subjects and also in wildlife exposed to azole fungicides used in agriculture.

Aromatase in primate pregnancy: a review

Aromatase enzyme is a cytochrome P450 protein that can catalyze the aromatization of C 19 androgens and thus their conversion into estrogens. It is tissue-specifically expressed in primate placenta, connective tissue, ovary, and brain through alternative splicing of tissue selective promoters. Human aromatase activity is critical for maintenance of early and mid pregnancy and in regulating parturition in late pregnancy. It is also important in the development of fetal gonadocytes and the sexual differentiation of brain, especially the hypothalamic-gonadal axis. Exposure to aromatase inhibitors in primates significantly impairs pregnancy outcome. Recent case reports have described syndromes associated with rare autosomal recessive mutations in aromatase genes.