Iris Klaiber

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The enzymatic transgalactosylation from lactose to fructose leading to the prebiotic disaccharide lactulose was investigated using the beta-galactosidase from Aspergillus oryzae and the hyperthermostable beta-glycosidase from Pyrococcus furiosus (CelB). The conditions for highest lactulose yields relative to the initial lactose concentration were(More)
Two new hydrolyzable tannins, isoterchebulin (1) and 4,6-O-isoterchebuloyl-D-glucose (2), together with six known tannins, 3-8, were isolated from the bark of Terminalia macroptera. Their structures were elucidated by extensive 1D and 2D NMR studies, MS, and chemical transformations. Biological activities of all compounds were evaluated against the snail(More)
MAPK signalling is a complex process not only requiring the core components Raf, MEK and Erk, but also many proteins like the scaffold protein KSR and several kinases to specifically localize, modulate and fine-tune the outcome of the pathway in a cell context specific manner. In mammals, protein kinase CK2 was shown to bind to the scaffold protein KSR and(More)
The phytochemical investigation of the aerial parts of Tribulus terrestris of Bulgarian origin has resulted in the isolation of the novel furostanol saponin 1, named tribol, together with the known spirostanol saponins 2 and 3 and sitosterol glucoside. The structure of tribol was determined as(More)
A new phenolic glucoside gallate, vanillic acid 4-O-beta-D-(6'-O-galloyl) glucopyranoside (1) was isolated from the bark of Terminalia macroptera Guill.et Perr., together with 3,3',4'-tri-O-methylellagic acid (2) and two triterpene glucopyranosyl esters, 24-deoxysericoside (3) and chebuloside II (4). Compounds 2-4, not described previously for this plant,(More)
The corrinoids synthesized by the sulfate-reducing bacterium Desulfovibrio vulgaris were analyzed. The compounds found were guanylcobamide and hypoxanthylcobamide; structures were determined by mass spectrometry, 1H-NMR, and ultraviolet/visible spectroscopy. D. vulgaris used externally added guanine to form guanylcobamide, as demonstrated with(More)
Four betacyanin pigments were analysed by LC NMR and subjected to extensive NMR characterisation after isolation. Previously, low pH values were applied for NMR investigations of betalains resulting in rapid degradation of the purified substances thus preventing extensive NMR studies. Consequently, up to now only one single (13)C NMR spectrum of a betalain(More)
Extracts of apple fruits (Malus domestica cv. "Brettacher") were analysed by HPLC with photodiode array detection. An unknown peak was monitored displaying the same retention time as isorhamnetin 3-O-glucoside. Preliminary identification of the isorhamnetin aglycone was performed by comparison of UV spectral data of the unknown compound with a reference(More)
Two new cyclic heptapeptides, integerrimides A and B, have been isolated from the latex of Jatropha integerrima. Their structures were elucidated by using extensive 1D and 2D NMR, MS, and chemical degradation. At 50 microM both peptides 1 and 2 significantly inhibited neurite outgrowth in neuronal cell culture. They also partially inhibited proliferation of(More)
Ganglioside patterns from crucian carp brain, muscle, and liver as well as liver gangliosides of roach, carp, the cichlid Oreochromis mossambicus, pigeon, dwarf hamster, and calf were comparatively analyzed by high performance thin layer chromatography (HPTLC). To achieve a rapid estimation on potentially interesting ganglioside compounds,(More)