The 4-hydroxyestrone: Electron emission, formation of secondary metabolites and mechanisms of carcinogenesis

A review of the biotransformations of priority pharmaceuticals in biological wastewater treatment processes

Wastewater effluent discharges have been considered as one of the main sources of synthetic chemicals entering into the aquatic environment. Even though they occur at low concentrations, pharmaceutically active compounds (PhACs) can have an impact on ecological toxicity that affects aquatic organisms. Moreover, new regulations in development toward preserving water quality reinforces the increasing need to monitor and abate some PhACs in wastewater treatment plants (WWTPs), where they are typically only partially eliminated. Unlike most previous reviews, we have focussed on how the main biological and chemical molecular factors impact the biotransformations of key PhACs in biological WWTP processes. Biotransformations have been found to be an important contributor towards the removal of PhACs from WWTP effluents. This review paper critically assesses these aspects and the recent advances that have been achieved in wastewater treatment processes for biodegradation of 7 PhACs; namely the non-steroidal anti-inflammatory drug (NSAID) diclofenac (DCF); the macrolide antibiotics azithromycin (AZM), erythromycin (ERY) and clarithromycin (CLR); the two natural estrogens estrone (E1) and 17β-estradiol (E2), and the synthetic estrogen 17α-ethinylesradiol (EE2). These represent the micropollutants of the EU Watch list in Decision 2015/495/EU that are most relevant to WWTPs due to their frequent detection. The metabolic pathways, transformation products and impact of relevant factors to biological WWTP processes is addressed in this review. The biokinetics of PhAC biodegradation in different engineered bioprocesses is also discussed. Promising technologies and operational strategies that are likely to have a high impact on controlling PhAC releases are highlighted and future research needs are also proposed.

Meta-analysis of gene expression profiles identifies differential biomarkers for hepatocellular carcinoma and cholangiocarcinoma

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) are the members of hepatobiliary diseases. Both types of cancer often exert high levels of similarity in terms of phenotypic characteristics, thus leading to difficulties in HCC and CCA differential diagnoses. In this study, a transcriptome meta-analysis was performed on HCC and CCA microarray data to identify differential transcriptome networks and potential biomarkers for HCC and CCA. Raw data from nine gene expression profiling datasets, consisting of 1,185 samples in total, were methodologically compiled and analyzed. To evaluate differentially expressed (DE) genes in HCC and CCA, the levels of gene expression were compared between cancer and its normal counterparts (i.e., HCC versus normal liver and CCA versus normal bile duct) using t test (P < 0.05) and k-fold validation. A total of 226 DE genes were specific to HCC, 249 DE genes specific to CCA, and 41 DE genes in both HCC and CCA. Gene ontology and pathway enrichment analyses revealed different patterns between functional transcriptome networks of HCC and CCA. Cell cycle and glycolysis/gluconeogenesis pathways were exclusively dysregulated in HCC whereas complement and coagulation cascades as well as glycine, serine, and threonine metabolism were prodominantly differentially expressed in CCA. Our meta-analysis revealed distinct dysregulation in transcriptome networks between HCC and CCA. Certain genes in these networks were discussed in the context of HCC and CCA transition, unique characteristics of HCC and CCA, and their potentials as HCC and CCA differential biomarkers.

Estrone direct photolysis: by-product identification using LC-Q-TOF

The identification of degradation products generated upon photolysis of estrone (E1), a natural estrogenic hormone, under simulated UV irradiation conditions was addressed by the use of LC-Q-TOF mass spectrometry. The structures of the main degradation products were elucidated, demonstrating how the use of model molecules 5,6,7,8-tetrahydro-2-naphtol (THN), 2-methylcyclopentanone (MCP), labeled molecule estrone D(4) (E1-D(4)), the investigation of the fragmentation pathways of the parent E1, the concurrent use of CID and exact mass measurements permit the characterization of structural modifications induced by photodegradation processes. In the present study, we identified nine major by-products of which seven photoproducts correspond to E1H(+) modified in positions other than the C-2, C-4 and C-16 of E1. Most of them showed one to three additional hydroxylations preferentially located on the aromatic ring of the parent E1, which confirms that these products may present environmental risk. Applications to real water samples have been conducted to extend the validity of the present study to environmental samples.

The effect of progesterone on the electron emission and degradation of testosterone

Based on recent findings that hormones can emit electrons () from their excited singlet state in polar media, it was of importance to study a possible mutual interaction of progesterone (PRG) and testosterone (TES) in this respect. Hormones of highest purity were dissolved in an air-free mixture of 40% triply distilled water and 60% ethanol, because the hormones are unsoluble in water. As energy source for substrate excitation in singlet state served a monochromatic UV-light (254 nm), the emitted electrons were scavenged by chloroethanol, whereby the quantum yield of produced Cl⁻ ions, Q (Cl⁻), is equal to Q(e⁻(aq)). Hormone degradation initiated by the electron emission was studied by HPLC method, using a Zorbax Eclipse XDB-C18 column (150 mm x 4.6 mm, 5 μm). The quantum yield of emitted e⁻(aq), Q(e⁻(aq)), from TES was 3.6 times higher than that from PRG, which is explained by the different molecular structures of the hormones. Observed 2nd and 3rd maxima of electron emission indicate the ability of TES and PRG products to also eject e⁻(aq), but with lower yield. It can be stated that a part of the emitted electrons from TES are consumed by PRG⁺ leading to a partial regeneration of hormone. The present results offer a deeper insight in the biological behavior of hormones.

Photo-induced regeneration of hormones by electron transfer processes: Potential biological and medical consequences

Based on the previous results concerning electron transfer processes in biological substances, it was of interest to investigate if hormone transients resulting by e.g. electron emission can be regenerated.

The presented results prove for the first time that the hormone transients originating by the electron emission process can be successfully regenerated by the transfer of electrons from a potent electron donor, such as vitamin C (VitC). Investigations were performed using progesterone (PRG), testosterone (TES) and estrone (E1) as representatives of hormones. By irradiation with monochromatic UV light (λ=254 nm) in a media of 40% water and 60% ethanol, the degradation as well as the regeneration of the hormones was studied with each hormone individually and in the mixture with VitC as a function of the absorbed UV dose, using HPLC. Calculated from the obtained initial yields, the determined regeneration of PRG amounted to 52.7%, for TES to 58.6% and for E1 to 90.9%. The consumption of VitC was determined in the same way.

The reported results concerning the regeneration of hormones by the transfer of electrons from an electron donor offer a new, promising method for the therapy with hormones. As a consequence of the regeneration of hormones, a decreased formation of carcinogenic metabolites is expected.

Electron emission and product analysis of estrone: progesterone interactions studied by experiments in vitro

Recent studies showed that hormones like progesterone, testosterone, etc. can eject [Formula: see text] (solvated electrons). By means of electron transfer processes via the brain, the hormones communicate with other biological systems in the organism. The present study proves that also estrone is able to emit electrons. Their yield strongly depends on the concentration of the hormone, temperature and on the absorbed energy. The metabolites resulting from this process are likewise able to generate electrons, however with much smaller yields. The formation of the estrone metabolites is studied by HPLC-analyses. In vitro experiments with MCF-7 cells demonstrate the distinct effect of progesterone on the carcinogenity of estrone metabolites. Probable reaction mechanisms for explanation of the observed effects are postulated.

Method for regeneration of hormones: 17β-estradiol, 21α-hydroxyprogesterone and corticosterone. A pathway for a possible medical application

The hormones 17β-estradiol (17βE2), 21α-hydroxyprogesterone (21α-HOPRG) and corticosterone (CORT) were used as representative models for the study. As a source for hormone excitation in singlet state serviced monochromatic UV-light (λ=254 nm), it was stated that the transients resulting by e

Mutual interaction of 17beta-estradiol and progesterone: electron emission. Free radical effect studied by experiments in vitro

BACKGROUND

Based on the different behaviour of 17beta-estradiol (17betaE(2)) and progesterone (PRG), it was of interest to investigate the interaction of both hormones in respect of their electron emission and cytotoxicity by experiments in vitro.

MATERIALS AND METHODS

The studies include determination of emitted electrons (e(-)(aq)) by the individual hormones as well as by their mixtures, all complexed with cyclodextrin (HBC). Experiments in vitro (Escherichia coli bacteria) were performed for a better understanding of the mechanisms involved. Survival ratios, DeltaD(37)(Gy), were calculated.

RESULTS

Aqueous HBC as well as 17betaE(2) and PRG, individually as well as in mixtures, are able to emit e(-)(aq). The resulting transients can lead to the formation of metabolites, some of which can initiate cancer. It was established that both hormones, 17betaE(2) and PRG, interact in respect to their electron emission property. In the frame of experiments in vitro, it was found that oxidizing radicals (OH, O(2)(-)) lead to negative DeltaD(37)(Gy) values, indicating cytostatic properties. On the other hand, the primary reducing radicals (e(-)(aq), H) lead to positive DeltaD(37)(Gy) values, indicating a radical-scavenging effect.

CONCLUSION

The main outcome of this work is that PRG in combination with 17betaE(2) can strongly reduce the number of carcinogenic 17betaE(2)-metabolites. This fact offers a new pathway for application of hormones in medical treatment of patients.

17beta-estradiol acting as an electron mediator: experiments in vitro

BACKGROUND

The present work reports on the effect of oxidizing (OH, O(2)(*-)) and reducing free radicals (e(-)(aq), H) on 17beta-estradiol (17betaE2) in respect to breast cancer initiation. The objectives of the study were based on the following premise: the ability of 17betaE2 to emit electrons (e(-)(aq)) as well as to transfer them to other biological systems. Thereby, the resulting transient hormone products are leading to the formation of metabolites, some of which may initiate the neoplastic process. The present work considers the effect of the simultaneously generated oxidizing and reducing free radicals on the carcinogenic properties of the 17betaE2 metabolites.

MATERIALS AND METHODS

Water-soluble 17betaE2 with incorporated 2-hydroxypropyl-beta-cyclodextrin (HBC) in various aqueous media (pH ~7.4), saturated with air, N(2)O or argon, as well as HBC alone, were exposed to the action of free radicals produced by gamma-ray. Escherichia coli bacteria (AB 1157) were used as a model for living systems.

RESULTS

From the survival curves obtained under different conditions, the derived DeltaD(37) values (representing the radiation dose at which N/N(0)=0.37; N/N(0) ratio: N(0)=starting number of colonies, N=number after irradiation treatment) illustrate that 17betaE2 as well as HBC act as very powerful scavengers of OH and O(2)(*-) radicals. On the other hand, 17betaE2 and HBC intermediates resulting from attack of the reducing species (e(-)(aq), H) have strong anticancer properties.

CONCLUSION

It is stated that DeltaD(37) values strongly depend on the reactivity of the individual free radicals. Oxidizing free radicals lead to positive DeltaD(37) values, illustrating the strongly pronounced radiation protecting ability of the systems. On the contrary, the primary reducing free radicals result in negative DeltaD(37) values, indicating anticancer effect.