Fragmentierung von α,β-Epoxy-ketoximen zu Acetylenketonen. Vorläufige Mitteilung

A new version of the oxidoketone-alkynone fragmentation is described. Two steroidal α,β-oxido-oximes are shown to fragment to the corresponding alkynones when treated with hydroxylamine-O-sulfonic acid in alcaline solution at room temperature.     

Phage-display selection of a human single-chain fv antibody highly specific for melanoma and breast cancer cells using a chemoenzymatically synthesized G(M3)-carbohydrate antigen

Overexpression of the cell-surface glycosphingolipid G(M3) is associated with a number of different cancers, including those of the skin, colon, breast, and lung. Antibodies against the G(M3) epitope have potential application as therapeutic agents in the treatment of these cancers. We describe the chemoenzymatic synthesis of two G(M3)-derived reagents and their use in the panning of a phage-displayed human single-chain Fv (scFv) antibody library derived from the blood of cancer patients. Three scFv-phage clones, GM3A6, GM3A8, and GM3A15, were selected for recombinant expression and were characterized using BIAcore and flow cytometry. BIAcore measurements using the purified, soluble scFvs yielded dissociation constants (K(d)) ranging from 4.2 x 10(-7) to 2.1 x 10(-5) M. Flow cytometry was used to evaluate the ability of each scFv to discriminate between normal human cells (human dermal fibroblast, HDFa), melanoma cells (HMV-1, M21, and C-8161), and breast cancer cells (BCM-1, BCM-2, and BMS). GM3A6 displayed cross-reactivity with normal cells, as well as tumor cells, and GM3A15 possessed little or no binding activity toward any of the cell lines tested. However, GM3A8 bound to five of the six tumor cell lines and showed no measurable reactivity against the HDFa cells. Hence, we have demonstrated that a synthetic G(M3) panning reagent can be used to isolate a fully human scFv that is highly specific for native G(M3) on the surface of tumor cells. The result is a significant step toward effective immunotherapies for the treatment of cancer.     

Properties of multiplicity distributions in νA and\bar v A intersections atE_{\begin{array}{*{20}c} {( - )} \\ v \\ \end{array} }< 30GeV

We present data on the multiplicity structure of inclusive charged hadron production in charged current neutrino and antineutrino freon interactions in the energy range 3–30 GeV resulting from an experiment with the bubble chamber SKAT. Average multiplicities, dispersions and correlation coefficients are investigated. Furthermore, KNO-scaling is studied and average net charges are calculated in different kinematical regions. Our data are compared with results from \(\begin{array}{*{20}c} {( - )} \\ v \\ \end{array} \) -interactions on an isoscalar target of “free” nucleons to study the influence of nuclear effects.     

Phototoxic effects of Hypericum extract in cultures of human keratinocytes compared with those of psoralen

Extracts of Hypericum perforatum (St. John's wort) are used in the treatment of depression. They contain the plant pigment hypericin and hypericin derivates. These compounds have light-dependent activities. In order to estimate the potential risk of phototoxic skin damage during antidepressive therapy, we investigated the phototoxic activity of hypericin extract using cultures of human keratinocytes and compared it with the effect of the well-known phototoxic agent psoralen. The absorbance spectrum of our Hypericum extract revealed maxima in the whole UV range and in parts of the visible range. We cultivated human keratinocytes in the presence of different Hypericum concentrations and irradiated the cells with 150 mJ/cm2 UVB, 1 J/cm2 UVA or 3 h with a white light of photon flux density 2.6 mumol m-2 s-1. The determination of the bromodeoxyuridine incorporation rate showed a concentration- and light-dependent decrease in DNA synthesis with high hypericin concentrations (> or = 50 micrograms/mL) combined with UVA or visible light radiation. In the case of UVB irradiation a clear phototoxic cell reaction was not detected. We found phototoxic effects even with 10 ng/mL psoralen using UVA with the same study design as in the case of the Hypericum extract. These results confirm the phototoxic activity of Hypericum extract on human keratinocytes. However, the blood levels that are to be expected during antidepressive therapy are presumably too low to induce phototoxic skin reactions.     

Hydrophobic interaction chromatography for the purification of a mycobacterial heat shock protein of relative molecular mass 60,000.

A recombinant mycobacterial heat shock protein of relative molecular mass 60,000 was purified by hydrophobic interaction chromatography. Chromatographic media with ligands of medium hydrophobicity, such as phenyl-Sepharose, bound too strongly to be used for the purification of this heat shock protein. Butyl-Sepharose, with weak hydrophobicity, allowed binding and elution with decreasing concentrations of ammonium sulphate, but only alkyl-Superose allowed the separation of two similar proteins from the Escherichia coli clone expressing the recombinant heat shock protein (relative molecular mass 60,000) of Mycobacterium bovis BCG. The binding parameters of recombinant human heat shock proteins of relative molecular mass 60,000 and 70,000 indicate that phenyl-Sepharose also binds too strongly for the separation of these two heat shock proteins.     

Die Glykoside der Samen von Stapelia gigantea N. E. Br. Glykoside und Aglykone, 275. Mitteilung

The seeds of Stapelia gigantea are very rich in ester glycosides (ca. 5,9%). Mild acid hydrolysis gave a mixture of sugars which, after paper chromatography and electrophoresis, was found to be probably composed of cymarose, oleandrose, digitoxose, arabino-2,6-dideoxyhexose (= canarose) and pachybiose. The mixture of the raw genins gave after alkaline hydrolysis a mixture of about nine deacyl genins (C, D, E, F1, F2, F3, G, H, J); the acids split off during hydrolysis were not identified. The nine deacyl genins are probably closely related pregnane derivatives. The main component (E), C₂₁H₃₀O₄, was obtained in crystalline state, and was named stapelogenin. Its probable structure is reported in the following publication.     

Rapid liquid chromatographic-mass spectrometric analysis of withanolides in crude plant extracts by use of a monolithic column

Summary A rapid analytical method has been developed for the mutual resolution of three steroidal compounds, withaferin A, iochromolide, and withacnistin. Liquid chromatography was performed on a Chromolith analytical column (4.6 mm i.d.×50 mm), made from a cylindrical silica rod, operated at a flow rate of 4 mL min⁻¹ with a simple linear gradient prepared from 0.1% aqueous formic acid and 0.1% formic acid in acetonitrile. Under optimum conditions simultaneous separation of the compounds was achieved in less than 7 min, one eighth the time required for conventional LC separation. The overall analysis time was reduced without sacrificing chromatographic performance—essential for the resolution of positional isomers such as iochromolide and withacnistin. The column was coupled to a single-quadrupole mass spectrometer and the method was characterized by good performance in terms of repeatability, selectivity, linearity, and sensitivity. Detection limits in the single-ion-monitoring mode were 0.15 μg mL⁻¹ or below. Finally, the developed method was successfully applied to the determination of withanolides in extracts fromlochroma gesnerioides obtained by three different processes—traditional Soxhlet extraction and two faster methods, microwave-assisted extraction and pressurized solvent extraction.     

Synthese und Charakterisierung neuer intramolekular stickstoffstabilisierter Organoaluminium‐ und Organogalliumalkoxide

Synthesis and Characterization of New Intramolecularly Nitrogen‐stabilized Organoaluminium‐ and Organogallium Alkoxides The intramolecularly nitrogen stabilized organoaluminium alkoxides [Me₂Al{μ‐O(CH₂)₃NMe₂}]₂ ( 1a ), Me₂AlOC₆H₂(CH₂NMe₂)₃‐2,4,6 ( 2a ), [(S)‐Me₂Al{μ‐OCH₂CH(i‐Pr)NH‐i‐Pr}]₂ ( 3a ) and [(S)‐Me₂Al{μ‐OCH₂CH(i‐Pr)NHCH₂Ph}]₂ ( 4 ) are formed by reacting equimolar amounts of AlMe₃ and Me₂N(CH₂)₃OH, C₆H₂[(CH₂NMe₂)₃‐2,4,6]OH, (S)‐i‐PrNHCH(i‐Pr)CH₂OH, or (S)‐PhCH₂NHCH(i‐Pr)CH₂OH, respectively. An excess of AlMe₃ reacts with Me₂N(CH₂)₂OH, Me₂N(CH₂)₃OH, C₆H₂[(CH₂NMe₂)₃‐2,4,6]OH, and (S)‐i‐PrNHCH(i‐Pr)CH₂OH producing the “pick‐a‐back” complexes [Me₂AlO(CH₂)₂NMe₂](AlMe₃) ( 5 ), [Me₂AlO(CH₂)₃NMe₂](AlMe₃) ( 1b ), [Me₂AlOC₆H₂(CH₂NMe₂)₃‐2,4,6](AlMe₃)₂ ( 2b ), and [(S)‐Me₂AlOCH₂CH(i‐Pr)NH‐i‐Pr](AlMe₃) ( 3b ), respectively. The mixed alkyl‐ or alkenylchloroaluminium alkoxides [Me(Cl)Al{μ‐O(CH₂)₂NMe₂}]₂ ( 6 ) and [{CH₂=C(CH₃)}(Cl)Al{μ‐O(CH₂)₂NMe₂}]₂ ( 8 ) are to obtain from Me₂AlCl and Me₂N(CH₂)₂OH and from [Cl₂Al{μ‐O(CH₂)₂NMe₂}]₂ ( 7 ) and CH₂=C(CH₃)MgBr, respectively. The analogous dimethylgallium alkoxides [Me₂Ga{μ‐O(CH₂)₃NMe₂}]₂ ( 9 ), [(S)‐Me₂Ga{μ‐OCH₂CH(i‐Pr)NH‐i‐Pr}]_n ( 10 ), [(S)‐Me₂Ga{μ‐OCH₂CH(i‐Pr)NHCH₂Ph}]_n ( 11 ), [(S)‐Me₂Ga{μ‐OCH₂CH(i‐Pr)N(Me)CH₂Ph}]_n ( 12 ) and [(S)‐Me₂Ga{μ‐OCH₂(C₄H₇NHCH₂Ph)}]_n ( 13 ) result from the equimolar reactions of GaMe₃ with the corresponding alcohols. The new compounds were characterized by elemental analyses, ¹H‐, ¹³C‐ and ²⁷Al‐NMR spectroscopy, and mass spectrometry. Additionally, the structures of 1a , 1b , 2a , 2b , 3a , 5 , 6 and 8 were determined by single crystal X‐ray diffraction.