Synthesis, structure, spectral and luminescence studies of novel guanidinium aryl(oxy)(sulfanyl)(sulfonyl)acetates.

A series of promising luminescent materials, nonlinear optical crystals, and physiologically active compounds - aryl(oxy)(sulfanyl)(sulfonyl)acetates of guanidine (A) of unknown type was synthesized. Various functional groups present in (A) were identified using FTIR spectroscopy. 1H and 13C NMR spectral studies further confirm the molecular structure (A). Crystals of guanidinium 4-chlorophenyl(sulfanyl)acetate (1) and guanidinium 4-chlorophenyl(sulfonyl)acetate (2) were successfully grown. They belong to the same lowest symmetry category, but to different crystal systems: monoclinic (1) and orthorhombic (2). It has been established that intrinsic optical absorption begins at a wavelength of âˆ¼ 290 nm for crystalline compound (1) and âˆ¼ 335 nm for crystal (2). The intrinsic luminescence spectrum of crystal (1) includes two bands with maxima at 300 and 515 nm. In the intrinsic luminescence spectrum of crystal (2), only one band is observed with a maximum at 350 nm. Such luminescence in both crystals is excited in the intrinsic absorption bands, as well as by X-ray radiation. In addition, in the near ultraviolet and throughout the visible region, where optical absorption is not detected (it is very weak), low-inertia (less than 10 ns) rather intense luminescence of uncontrolled impurity-defect centers is excited. The spectral bands of optical absorption, photo- and X-ray luminescence discovered in experiments were systematized using a diagram of energy levels and quantum transitions in crystals and defect centers of the compounds under study.

[Slow Formation and Degradation of γH2AX Foci in Human Skin Fibroblasts Exposed to Low-Dose X-Ray Radiation].

It was shown that the kinetics of changes of γH2AX foci number (marker of DNA double-strand breaks) in human skin fibroblasts after exposure to low doses of X-ray radiation (20, 40 and 80 mGy) differs from that observed after exposure to medium-low doses (160 and 240 mGy). After exposure to 160 and 240 mGy the highest number of γH2AX foci was detected at 30 min after exposure (first experimental point) and further their decrease was observed. At the same time we observed a fast phase of repair (upto 4 h), in which there was a decrease of the foci amount to ~50-60% and a slow phase of repair (from 4 h to 24 h). After 24 h only ~3-5% of the foci amount observed at 30 min after irradiation was left. After exposure to low doses, the foci number did not decrease during 2 h and even 24 h after exposure their amount was ~25% from that observed at maximum points (1 h after irradiation at 40 and 80 mGy and 2 h after irradiation at 20 mGy).

[The inhibiting effect of phytoadaptogenic preparations from bioginseng, Eleutherococcus senticosus and Rhaponticum carthamoides on the development of nervous system tumors in rats induced by N-nitrosoethylurea]. / Tormoziashchii éffekt fitoadaptogennykh preparatov biozhen'shenia, éleuterokokka koliuchego i levzei saflovidnoi na razvitie opukholei nervnoi sistemy u krys, indutsirovannykh N-nitrozoétilmochevinoi.

The study was concerned with the inhibitory effect of officinal preparations of phytoadaptogenic drugs such as bioginseng and Eleutherococcus senticosus and Rhaponticum carthamoides root extracts on the carcinogenesis induced by transplacental administration of N-nitrosoethylurea. The phytodrugs were given orally over a year. The administration of the drugs was followed by longer survival of the rats and lower occurrence and/or multiplicity of tumors (mainly those of the central nervous system). The drugs were placed in the order of decreasing anticarcinogenic activity as follows: bioginseng, Rhaponticum carthamoides extract and Eleutherococcus senticosus extract.