Polarographische Bestimmung von Diazepam in Leichenblut ohne vorherige Extraktion

Zusammenfassung Eine polarographische Methode zur direkten Bestimmung von Diazepam in Leichenblut ohne vorherige Extraktion wird beschrieben. Als Grundelektrolyt wird Britton-Robinson-Puffer (pH 2,8) und Methanol (41v/v) empfohlen. Die untere Bestimmungsgrenze liegt bei 20 g Diazepam/ml Blut.

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Polarographic determination of diazepam in cadaver blood without prior extraction

Summary A polarographic method is described for the direct determination of diazepam in cadaver blood without previous extraction. The fundamental electrolyte recommended is Britton-Robinson buffer solution (pH=2.8) and methanol (41v/v). The lower determination limit is situated at 20g diazepam/ml blood.

     

Effect of ethanol on the thermal stability of human serum albumin

The effect of ethanol on human serum albumin stability in aqueous solution was studied by use of differential scanning calorimetry. A deconvolution of DSC traces in 2-state model with ΔC _p=0 and ΔC _p≠0 was performed and analysed to obtain information on the interaction of ethanol with different parts of albumin molecule both fatty acid containing and fatty acid free. The differences in ethanol binding affinity for both kinds of albumin were found. At very low concentrations ethanol was observed to be a stabilizer of the folded state of albumin contrary to the higher concentration where its binding to the unfolded protein predominates.     

Collisionally activated dissociation of some pyridinium cations: Novel fragmentation pathways

Three novel collisionally induced dissociation pathways, additional to the usual formation of pyridine or pyridinium cation, are described for laser-desorbed N-substituted pyridinium cations. Particularly prevalent is the formation of an ion of m/z 94, corresponding to [PyCH₃]⁺. Doubly charged pyridiniums tend to lose H⁺, and one example of the apparent formation of the neutral radical C₅H₆N˙ is reported.     

Rifamycin antibiotics—new compounds and synthetic methods. Part 1: Study of the reaction of 3-formylrifamycin SV with primary alkylamines or ammonia

Within the study covering the search for new methods of synthesis of rifamycin antibiotics, the reactions of 3-formylrifamycin SV (2) with primary amines or ammonia were studied. In the reaction of 2 with methylamine, unstable 3-methyliminomethylrifamycin SV (8) was formed, which was further oxidised to stable 3-methyliminomethylrifamycin S (9). In the reaction of 2 with ammonia, N,15-didehydro-15-deoxo-pyrimido-(4,5-b)rifamycin SV (10), a new compound with a chromophore system enlarged by a pyrimidine ring, was obtained. The product of its reduction with sodium borohydride—(11)—was also isolated. The structures of the compounds and an explanation of the synthesis mechanism have been proposed on the basis of mass spectrometry results as well as (1D) and (2D) ¹H- and ¹³C NMR analysis. In vitro antituberculous activity of the new compounds have been investigated.     

Formation and stabilization of persistent free radicals

We demonstrate that stable and relatively unreactive “environmentally persistent free radicals (PFRs)” can be readily formed in the post-flame and cool-zone regions of combustion systems and other thermal processes. These resonance-stabilized radicals, including semiquinones, phenoxyls, and cyclopentadienyls, can be formed by the thermal decomposition of molecular precursors including catechols, hydroquinones and phenols. Association with the surfaces of fine particles imparts additional stabilization to these radicals such that they can persist almost indefinitely in the environment. A mechanism of chemisorption and electron transfer from the molecular adsorbate to a redox-active transition metal or other receptor is shown through experiment, and supported by molecular orbital calculations, to result in PFR formation. Both oxygen-centered and carbon-centered PFRs are possible that can significantly affect their environmental and biological reactivity.     

STUDIES ON PYRAZINE DERIVATIVES. XL. SYNTHESIS,REACTIVITY, AND TUBERCULOSTATIC ACTIVITY OF 4-HYDROXYALKYL-5-PYRAZINYL4H-[1,2,4]-TRIAZOLE-3-THIONES

2,2′-Sulfinyl-bis(4-methyl phenol) 3 and it's thio derivative have been synthesized in this work. The reduction process of sulfoxide 3 to its thio derivative 5 was accomplished in the presence of Zn/AcOH/SiO₂, under microwave irradiation. The structures have been confirmed by spectroscopic (IR, ¹HNMR, ¹³CNMR) and single crystal x-ray diffraction methods. 2,2′-Sulfinyl-bis(4-methyl phenol) 3 crystallizes in the space group Cc of the monoclinic system with four molecules in the unit cell of dimensions a = 11.425(2) Å, b = 13.530(2) Å, c = 9.5215(17) Å, β = 117.289(4) Å, and 2,2′-thio-bis(4-methyl phenol) 5 crystallizes in the space group P 2₁2₁2₁ of the orthorhombic system with four molecules in the unit cell of dimensions a = 9.021(1) Å, b = 10.523(2) Å, c = 13.607(2) Å, α = 90. The structures have been refined to final values for the crystallographic R factor of 0.0189(3) and 0.0248(5) based on 2999 and 3720 observed independent reflections respectively.     

Quality Assessment of Wild and Cultivated Green Tea from Different Regions of China

Natural products have always enjoyed great popularity among consumers. Wild tea is an interesting alternative to tea from intensive plantations. The term “wild tea” is applied to many different varieties of tea, the most desirable and valued of which are native or indigenous tea plants. Special pro-health properties of wild tea are attributed to the natural conditions in which it grows. However, there are no complex studies that describe quality and health indicators of wild tea. The aim of this research was to evaluate the quality of wild and cultivated green tea from different regions of China: Wuzhishan, Baisha, Kunlushan, and Pu’Er. The assessment was carried out by verifying the concentration of selected chemical components in tea and relating it to the health risks they may pose, as well as to the nutritional requirements of adults. Wild tea was characterized by higher micronutrient concentration. The analyzed teas can constitute a valuable source of Mn in the diet. A higher concentration of nitrates and oxalates in cultivated tea can be associated with fertilizer use. The analyzed cultivated tea was a better source of antioxidants with a higher concentration of caffeine. There were no indications of health risks for wild or cultivated teas.     

Effects of low-dose ionizing radiation on α,β-globulins solutions studied by DSC

An attempt has been made to detect the effect of a small dose of ionizing radiation on the course of α,β-globulin thermal denaturation in aqueous solutions. Doses of 0.1 and 1.8 Gy have been delivered using γ-rays emitted by ⁶⁰Co isotope while doses of 10 and 100 Gy have been supplied by X-rays produced by linear accelerator. The highest dose has visibly changed DSC curve of protein solution while the changes due to lower doses are hardly detectable. Although very weak, the irradiation effect found has been dose dependent. The results suggest that the influence of ionizing radiation on globulins solution is bigger when the dose rate is lower at given dose. The opposite direction of differences between irradiated and control samples for fresh and stored protein solutions suggests various characters of changes in initial and later period of sample aging. This may be an important reason for difficulties in an investigation of the effect of ionizing radiation on protein solution, especially for low doses delivered very slowly.     

Ion cyclotron resonance mass spectrometric study of ion—molecule reactions in toluene—pyridine mixtures

Ion—molecule reactions in toluene, toluene-d₈, pyridine, 4-methyl-, 4-ethyl- and 4-terr-butylpyridine and quinoline and their mixtures were studied by ICR mass spectrometry at 10^-7 Torr (1 Torr = 133.3 Pa). The reactions of benzyl (m/z 91), benzyl-d₇ (m/z 98), methylbenzyl (m/z 105), and azabenzyl (m/z 92) ions with pyridines and quinoline were observed. The reactions of protonated pyridines with unprotonated molecules leading to homoconjugated ions (BHB)⁺ were detected.     

The influence of radio-frequency radiation on thermal stability of bovine serum albumin in aqueous solution

Protein unfolding events were studied by differential scanning calorimetry (DSC) for bovine serum albumin (BSA) aqueous solutions exposed to radio-frequency radiation. No immediate effect of this radiation on thermal unfolding of BSA was observed. The differences between irradiated and control samples have appeared during the storage of BSA solution. The irradiated samples changed faster than non-irradiated. Our results indicated that the age-related changes were stronger for 3.5 and 5 MHz than for 247 MHz frequency and dependent on energy power of radiation. Deconvolution of DSC traces allowed to study the effect of radio-frequency radiation on each component transition. This revised version was published online in July 2006 with corrections to the Cover Date.