Oxidative stress-induced cellular damage caused by UV and methyl viologen in Euglena gracilis and its suppression with rutin

The effects of ultraviolet radiation (UV-A: 320-400 nm and UV-B: 280-320 nm) and methyl viologen (MV) single or combined exposure, on the cell growth, viability and morphology of two strains of the unicellular flagellate Euglena gracilis, using the Z strain as a plant model and the achlorophyllous mutant SMZ strain as an animal model were investigated. Cell growth was not affected by MV only, whereas UV-A or UV-B single and combined exposure with MV inhibited the cell growth or decreased the viability. The SMZ strain had a higher number of abnormal cells than the Z strain after the third dose of UV-B was delivered simultaneously with MV. The abnormal cell number decreased when E. gracilis SMZ cells were preincubated with 100 microM rutin prior to the UV-B and MV exposure. There were higher abnormal cell numbers with groups exposed to UV rather than MV single exposure. Combined exposure to UV-B and 200 microM MV induced the highest levels of TBARS in both strains, and with the supplementation of rutin these high levels were suppressed. These results suggest that UV-A or UV-B irradiation alone or combined with MV cause considerable oxidative damage in E. gracilis cells, and rutin supplementation may suppress their adverse effects.     

Application of molecular orbital graph theory to vibrational problems of finite chain systems

A generating function approach based on molecular orbital graph theory is presented that provides a straightforward way of obtaining the secular polynomials and energy bands for repeated unit systems from polynomial recurrence expressions. The possibility of obtaining the analytical energy-level spectrum of the system can also be predicted. These results are then used to discuss the vibrational problems of finite chain systems with single- and double-component lattices. It seems to be the first report describing the vibrational states of an (AB)_N chain.     

Pre-resonance Raman effect and vibronic coupling of benzene and benzene-d6

The pre-resonance Raman effect was observed for liquid benzene and benzene-d₆. Great intensity enhancement was found for ν₁₀(e_1g), 2ν₈ and 2ν₁₄. The effect was expained in terms of vibronic couplings between the electronic states of the molecules.     

Access to Wieland-Miescher ketone in an enantiomerically pure form by a kinetic resolution with yeast-mediated reduction

Both enantiomers of Wieland-Miescher ketone [3,4,8, 8a-tetrahydro-8a-methyl-1,6(2H,7H)-naphthalenedione], in a highly enantiomerically enriched form, became readily available by a newly developed kinetic resolution with yeast-mediated reduction. From a screening of yeast strains, Torulaspora delbrueckii IFO 10921 was selected. The collected cells of this strain, obtained by an incubation in a glucose medium, smoothly reduced only the isolated carbonyl group of the (S)-enantiomer, while the (R)-enantiomer remained intact. Starting from both enantiomers ( approximately 70% ee) prepared by an established proline-mediated asymmetric Robinson annulation, the reduction with T. delbrueckii gave the (R)-enantiomer (98% ee) and the corresponding alcohol (4aS,5S)-4,4a, 5,6,7,8-hexahydro-5-hydroxy-4a-methyl-2(3H)-naphthalenone (94% ee, 94% de) in preparative scale in nearly quantitative yields. An approach for the asymmetric synthesis of the Wieland-Miescher ketone was also successful. 2-Methyl-2-(3-oxobutyl)-1,3-cyclohexanedione, the prochiral precursor, was reduced with this strain to give a cyclic acetal form of (2S, 3S)-3-hydroxy-2-methyl-2-(3-oxobutyl)cyclohexanone, in a stereomerically pure form.     

Diprotonation of nitroarenes

Cryoscopic measurement shows that 1-nitronaphthalene is diprotonated in trifluoromethanesulfonic acid (TFSA). The diprotonated nitronaphthalenes are N,N-dihydroxyiminium-naphthalenium dications, which is fully characterized by UV, ¹H-, ¹³C and ¹⁵N-NMR spectra.     

Rotational effects on the quantum yield and lifetime of the slow component of fluorescence from s-triazine

The fluorescence quantum yield and lifetime of the slow component of fluorescence obtained along the rotational contour of the 6¹₀ and 6²₀ absorption bands of s-triazine at low pressure show a marked variation. For each band, the quantum-yield spectrum shows a sharp peak at the Q-branch edge, the lifetime spectrum exhibits a valley at the same position.     

Molecular structure of bis(acetylacetonato)beryllium in the gas phase as determined from electron diffraction data

The molecular structure of bis(acetylacetonato)beryllium has been determined by gas electron diffraction. The experimental data were found to be consistent with the D_2d model in which the oxygen atoms are arranged tetrahedrally around the central beryllium atom (∠OBeO = 106.0 ± 1.0°). The structural parameters are as follows: r_g(Be-O) = 1.615 ± 0.006 Å, r_g (C-O) = 1.270 ± 0.004 Å, r_g (C-C_ring) = 1.397 ± 0.004 Å, r_g (C-C_meth) = 1.499 ± 0.005 Å. The mean amplitudes of vibration were calculated from the normal-vibration treatment using the modified Urey—Bradley force field     

Electrothermal atomic-absorption spectrometry of antimony by use of a molybdenum micro-tube atomizer

Electrothermal atomization of antimony has been investigated to clarify the atomization characteristics and interferences from diverse elements, for accurate determination of traces of antimony. Thiourea served to lower the atomization temperature of antimony and to improve the sensitivity. Germanium and phosphoric acid were found to have a pronounced effect on atomization of antimony. The interference of various elements was suppressed in the presence of thiourea. A method involving extraction for determining antimony in metallurgical and geological samples is described.     

The synthesis of pyrazolo[3,4-d]pyridazines. Photochemical cyclization to pyrazolo[3,4-d]pyridazin-4(5H)-ones with subsequent functionalization

The synthesis of 1,3-disubstituted and 1,3,5-trisubstituted 1H-pyrazolo[3,4-d]pyridazin-4(5H)-ones is conveniently performed by photochemical cyclization. Functionalization of the former compounds leading to the formation of 1,4-disubstituted and 1,3,4-trisubstituted 1H-pyrazolo[3,4-d]pyridazines is smoothly effected through pertinent nucleophilic substitutions.