Pulse Radiolysis Using Very-high-energy Ions for Optimizing Cancer Therapy.

Cancer therapy by means of high-energy ions is very efficient. As a consequence of the linear-energy-transfer effect only a negligible part of the produced free radicals can escape combination processes to form molecular products and to cause undesired side processes. Positrons (e⁺) and γ-rays, generated by the nuclear interaction of high-energy ions in the medium, serve in monitoring the radiation dose absorbed by the tumor. However, due to the dipole nature of water molecules a small proportion of thermalized positrons (e⁺th) can become solvated (e⁺aq). Hence, they are stabilized, live longer and can initiate side reactions. In addition, positronium (Ps), besides solvated electrons (e⁺aq), can be generated and involved in the reaction mechanisms. For a better understanding of the reaction mechanisms involved and to improve cancer therapy, a time-resolved pulse radiolysis instrument using high-energy particles is discussed here. The proposed method is examined and recommended by CERN experts. It is planned to be realized at the MedAustron Radiation Therapy and Research Centre in Wiener Neustadt, Austria.

Melatonin: Free Radicals and Metabolites Resulting by Emission and Consumption of Solvated Electrons (eaq-): Reaction Mechanisms.

BACKGROUND/AIM: Melatonin not only regulates circadian rhythm, but also induces apoptosis in tumor cells. Hence, elucidation of the basic reaction mechanisms of melatonin and its metabolites is a matter of interest. MATERIAL AND METHODS: Melatonin dissolved in a mixture of water/ethanol=40/60 form associates (unstable complexes). For simulation of biological processes, melatonin was excited by UV light into the singlet state. RESULTS: By using monochromatic UV light (λ=254 nm) melatonin ejects solvated electrons (eaq (-)), a part of which is scavenged by melatonin in ground state contained in the associates. Consequently, with increase of melatonin concentration a decrease of the determined quantum yield of emitted eaq (-), Q(eaq (-)), is obtained. The complex molecular structure of melatonin contains functional groups which can emit eaq (-), as well such consuming eaq (-). As a succession of these processes various types of metabolites are generated, as well as degradation products, with lower molecular weight, are formed. CONCLUSION: Not melatonin per se, but the ejected eaq (-) and thereby resulting various metabolites are responsible for different biological properties of melatonin.

Corticosterone metabolites originating as a consequence of solvated electron (e(-)aq) emission.

Corticosterone in water-ethanol solution can eject "solvated electrons" (eaq(-)) when excited into the singlet state by monochromatic UV-light (λ=254 nm). As a consequence of this process free radicals and H(+) ions were also generated. Hence, the objectives of this study were to determine the quantum yield, Q, at different corticosterone concentrations, and elucidate the fate of the generated free radicals and the involved reaction mechanisms. Because of the formation of associates, which consume a part of the emitted eaq(-), the Q decrease with increase of cortisone concentration. Additionally the H(+) ions scavenge and convert a part of the ejected eaq(-) into H-atoms. In comparsion with progesterone, the Q of corticosterone is much higher. Evidently, this effect is due to the two OH groups of corticosterone, which act as intense emission centres for eaq(-). Thereby, the generated free radicals from corticosterone lead to formation of metabolites, which were analyzed by combination of liquid-chromatography with mass spectrometry (LC/MS) method. Two of them were identified: 5α-pregnan-3α, 21-diol-11, 20-dione and 20ß-dihydroxycortisone. Both have the same mass number of 348.230. To explain the involved, rather complicated processes, a probable reaction mechanism is suggested.

Effect of cytochrome C and vitamin C on the survival of MCF-7 cancer cells under γ-ray treatment.

In the present study, the radiation-induced effect of cytochrome c (CytC) and vitamin C (VitC) is studied with respect to survival of MCF-7 cancer cells grown in aerated media. Both, CytC and VitC, were incubated with MCF-7 cancer cells under various concentrations individually, as well as in mixture and cells were subsequently treated with γ-ray in a dose range of 0 to 30 Gy. Generally, an increase of cell survival was observed under substance treatment up to a radiation dose of 5 Gy compared to the control group. Based on the obtained results it is believed that cell survival depends strongly on the action of free radicals produced at the given concentration of the incubated CytC and VitC as well as on the specific reaction rate constants (k: l mol(-1) s(-1)) of the involved processes.

Significance of solvated electrons (e(aq)-) as promoters of life on earth.

Based on the present state of knowledge a new hypothesis concerning the origin of life on Earth is presented, and emphasizes the particular significance of solvated electrons (e(aq)(-)). Solvated electrons are produced in seawater, mainly by (40)K radiation and in atmospheric moisture by VUV light, electrical discharges and cosmic ray. Solvated electrons are involved in primary chemical processes and in biological processes. The conversion of aqueous CO2 and CO into simple organic substances, the generation of ammonia from N2 and water, the formation of amines, amino acids and simple proteins under the action of e(aq)(-) has been experimentally proven. Furthermore, it is supposed that the generation of the primitive cell and equilibria of primitive enzymes are also realized due to the strong reducing property of e(aq)(-). The presented hypothesis is mainly founded on recently obtained experimental results. The involvement of e(aq)(-) in such mechanisms, as well as their action as an initiator of life is also briefly discussed.

Vitamin C: electron emission, free radicals and biological versatility.

The many-sided biological role of vitamin C (ascorbate) is briefly illustrated by specific examples. It is demonstrated that in aqueous solutions, vitamin C emits solvated electrons (e(aq)(-)), when excited in single state. Vitamin C can also react with e(aq)(-) as well as transfer them to other biological systems and thereby acts as efficient electron mediator. Based on its chemical and biological properties, it is clear that vitamin C plays a very important role in various functions in the organism alongside biochemical processes.

Formation of sex hormone transients resulting from attack of free radicals.

BACKGROUND: Transients of the sex hormones testosterone (TES) and estrone (E1) exhibit an impact on the carcinogenesis of most prostate and breast cancer types. For elucidation of involved reaction mechanisms, in vitro, experiments using γ-ray for generation of attacking hormone transients and UV-light (λ=254 nm) for excitation of hormone molecules were applied. Materials and Methods. Experiments in vitro (Escherichia coli AB1157) incubated with TES and E1, individually as well as in mixture with vitamin C (electron donor), were performed under γ-irradiation in water-alcohol (40/60) medium for clarifying-up the reaction mechanism. The hormone degradation/regeneration processes were studied by high performance liquid chromatography analysis. RESULTS: Independently of hormone molecular structure, the determining factor for the biological properties, such as carcinogenity, were found to be based on the hormone transients. The biological ability of these, however, depends on the chemical properties of the species attacking the corresponding hormone. Hormone degradation can be, at least partly, converted into hormone regeneration by electron transfer from an electron donor (e.g. vitamin C), when available during the period of status nascendi of the hormone radicals.

Vitamin-induced intracellular electrons are the mechanism for their well-known beneficial effects: a review.

A new conception of the action mechanisms of vitamins and some other compounds without a vitamin status is briefly presented. It is based on results obtained through pulse radiolysis, molecular radiation biological investigations, and in vitro studies. The data clearly show that antioxidant vitamins (C, E, ß-carotene) and B vitamins and related compounds possess the capability to emit "solvated electrons" in aqueous solutions or polar media. In consequence, the well-known vitamin effects are attributed to the action of the emitted solvated electrons and the resulting vitamin free radicals rather than the vitamin molecules per se, as generally accepted.

Fundamental biological importance of solvated electrons in humans.

Abstract In recent years, "solvated electrons" were shown to be emitted by various biological systems in humans such as hormones, enzymes, amino acids, etc., even by vitamins, dyes, and other organic compounds. Based on experimental results and data from the literature, it is hypothesized that most biological systems in humans are capable of emission. Most systems in humans generate as well as consume and transfer them to other moieties, hence enabling intersystem communication via the brain. Emission of is associated with generation of free radicals, which are likewise involved in biological processes in humans. The data presented in this article underline this hypothesis, which offers a completely new concept in the course of biological mechanisms in humans.

New findings concerning the mutual action of hormones and receptors.

The actual mechanisms concerning the role of the hormone-receptor complex cannot satisfactorily explain the various hormone activities. Photobiological studies were performed in order to gain a deeper insight in this respect. 17ß-estradiol (17ßE(2)) was used as representative hormone and methionine-enkephaline (ME) was used as an adequate model for a receptor. Their biological behaviors and mutual interactions were investigated in air-free media (pH~7.4; 37°C) by excitation in singlet state, using monochromatic UV-light (λ=254 nm; E=4.85 eV/hη). It was found that tyrosine (Tyr) as a main component of ME, as well as ME itself, can eject solvated electrons (e(aq)(-)), when excited in singlet state. The observed quantum yields, Q (e(aq)(-)), in both cases decreased with an increase of the corresponding substrate concentration. The effect is explained by the formation of associates (unstable complexes of molecules prevailing in the ground state), which consume a proportion of the emitted e(aq)(-). The ME transients, resulting from the electron emission, can partly regenerate by electron transfer from an efficient electron donor, e.g. ascorbate. 17ßE(2), like other hormones, can also eject electrons under the same experimental conditions. In a mix of 17ßE(2) and ME in air-free media (40/60 water/ethanol, pH~7.4; 37°C), a mutual electron exchange takes place. Thereby 17ßE(2) transients, being in status nascendy state, can partly regenerate by electron transfer from ME. Thus, the duration and action of 17ßE(2) are prolonged. To our knowledge this fact is reported for the first time and it is a finding of basic biological and medical importance.

Dopamine: effect of concentration and pH on the electron emission. Reaction mechanisms.

Dopamine (DA) in airfree, aqueous solution (pH 7.4; 37°C) is able to emit e(-)(aq) when electronically excited in its singlet state by monochromatic UV light (λ=254 nm; 4.85 eV/hν). The quantum yield Q(e(-)(aq)), was studied in dependence of DA concentration and pH of the media. The DA transients resulting from the electron emission form products, which also have the ability to emit e(-)(aq), but with much lower yield. Since DA in the ground state can consume e(-)(aq), it is classified as an electron mediator. Some biological consequences based on the e(-)(aq) emission are mentioned.

Cytochrome c: electron emission, photodegradation and mutual interaction with vitamin C.

Cytochrome c (Cytc) in airfree, aqueous media (pH ~7.4; 37°C) can emit e(-)(aq) when exited in single state by monochromatic UV light (λ=254 nm). The obtained Qi(e(-)(aq)) at lower Cytc concentrations is higher compared to the amount obtained at higher substrate concentrations because at >10(-8) mol l(-1) Cytc 'associates' (unstable complexes) are formed, which consume a part of the ejected e(-)(aq). The primary, as well as secondary, photolytic products of the substrate likewise emit e(-)(aq), but with much lower Qi(e(-)(aq)) values. On the other hand, the photolysis Q(Cytc) values are lower than those of Qi(e(-)(aq)), since Cytc transients can be regenerated by partial consumption of emitted e(-)(aq). In addition to this, the produced Cytc(•+) (radical cations) can react with water, thus also regenerating Cytc.

Hormones: electron emission, communication, mutual interaction, regeneration, metabolites, carcinogenesis and receptor action.

Abstract This review discusses the highlights of the recently made discovery about the ability of hormones to eject 'solvated electrons' (eaq-) in water containing media. The resulting consequences for communication with other biological systems by the electron-transfer process, formation of metabolites, the possible initiation of cancer, hormone regeneration and the action of hormone-receptor systems are briefly discussed. The molecular structure of the hormones and the environment are hereby found to be the most important determining factors for the yield of ejected eaq-. Furthermore, the hormone transients, which result from emission of eaq-, are reviewed, as well as the formation of metabolites, which can be involved in various biological processes. The hormone-transients can also be regenerated by electron-transfer from a potent electron donor, at least partly, as long as they are in a 'status nascendi state'. The discussion of all these effects is supported by corresponding experimental data and experiments in vitro. This review presents a complete new conception of the action mechanisms 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.

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.

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: 17ß-estradiol, 21α-hydroxyprogesterone and corticosterone. A pathway for a possible medical application.

The hormones 17ß-estradiol (17ßE2), 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-aq emission in air-free mixture water/ethanol 40/60, as long as they are in "status nascendi", can be regenerated by electron transfer from a potent electron donor, e.g., vitamin C. The hormone regeneration (%) strongly depends, after all, on specific hormone molecular structure, concentration, temperature, etc. Because of the large heterogenic molecular structures, the substrates dissolved in the solvent mixture form "associates" (unstable complexes) in concentrations >109 mol/L hormone. The hormones eject, but they also consume e-aq with a rather high reaction rate constant (k≈109 up to 2×1010 L/mol.s), therefore, they act as "electron mediators". It was also observed that the hormones by dissolution in aerated solvent mixture are sensitive towards oxygen. For an explanation of the results, probable reaction mechanisms are presented. The described method offers a new pathway and possibilities for application in medicine.

Metabolite formation of 17alpha-hydroxyprogesterone as a consequence of e⁻(aq)-emission and progesterone effect regarding cancer.

Based on previous investigations on several hormones, 17α-hydroxyprogesterone (17α-HOPRG) was studied in respect to cancer initiation by its metabolites resulting from electron emission. The emission of electrons (e⁻(aq)) from its singlet excited state of 17α-HOPRG and HPLC-analysis of products were studied. Possible carcinogenicity of metabolites originating from 17α-HOPRG and the effect of progesterone (PRG) in this respect were studied in vitro. The results showed that 17α-HOPRG is very sensitive towards oxygen. The highest Q(e⁻(aq)) values were obtained by dissolution and UV-irradiation of substrate in airfree media. 17α-HOPRG metabolites showed a strong anticancer activity, which is, however, lower compared to that of PRG-metabolites. Mixture of both hormones, 17α-HOPRG and PRG, in respect to carcinogenicity showed a synergistic effect of PRG on 17α-HOPRG. Reaction mechanisms are presented.

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.