Heike Schittl

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

4-Hydroxyestrone (4-OHE(1)), a typical cancer-inducing metabolite, originating from 17beta-estradiol (17beta-E2), was chosen as a model for the studies. The aim was to get a deeper insight in the mechanisms of its ability to initiate cancer. It was found, that 4-OHE(1) can eject electrons (e(aq)(-)), when excited in the singlet state by monochromatic UV-light (lambda=254 nm) in polar media (water:ethanol=40:60 vol.%). The quantum yield Q(e(aq)(-)), determined for various 4-OHE(1) concentrations, is found to be as high as that previously observed for 17beta-E2. It decreases with increasing substrate concentration, but it is enhanced at higher temperature. The ability of 4-OHE(1) to eject as well as to consume and to transfer electrons to other biological systems, classifies it as an electron mediator, similar to 17beta-E2. The 4-OHE(1) transients resulting of the electron emission process are leading to the formation of secondary metabolites. Surprisingly, it was established that the secondary metabolites possess likewise the ability to eject as well as to consume electrons. Hence, they behave similar like 17beta-E2. However, the structure of the secondary formed metabolites, which determinates their biological properties and carcinogenity, depends on the nature of the available reaction partners involved in their formation. A probable reaction mechanism explaining the subject matter is discussed.

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 (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.

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(). Hormone degradation initiated by the electron emission was studied by HPLC method, using a Zorbax Eclipse XDB-C18 column (150 mm × 4.6 mm, 5 μm). The quantum yield of emitted , Q(), 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 , 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.

Radiation-induced antitumor properties of vitamin B5 (pantothenic acid) and its effect on mitomycin C activity: experiments in vitro.

Vitamin B5 (pantothenic acid) shows a strongly pronounced antitumor effect under the influence of ionizing radiation. In the frame of experiments in vitro (model: Escherichia coli bacteria, AB1157) performed under the exact knowledge of concentration and kind of the free radicals acting in the various aqueous media (pH 7.4) the following was established: (i) vitamin B5 possesses a very intense antitumor property, (ii) it exerts a strong synergistic effect on mitomycin C (MMC), (iii) the oxidizing species (OH*, O2*-) appears to be most important in the initiation of the observed effect. The generated radiolytic products from vitamin B5 very likely also play an important role in this respect.