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Regensburg, Germany

Kovalska V.,NASU Institute of Molecular Biology and Genetics | Chernii S.,NASU Institute of Molecular Biology and Genetics | Losytskyy M.,NASU Institute of Molecular Biology and Genetics | Dovbii Y.,Vernadskii Institute of General and Inorganic Chemistry | And 5 more authors.
Dyes and Pigments | Year: 2016

The series of the β-ketoenoles (2E,5Z,7E,9E)-2-(alkylamino)-6-hydroxy-10-phenyldeca-2,5,7,9-tetraen-4-ones with variation of the alkylamino tail groups was synthesized and studied as potential probes for the sensing of protein insoluble aggregates - amyloid fibrils. Depending on the structure of the alkylamino group, the dyes could increase their fluorescence intensity in the dozens of times in the presence of insulin fibrils. The compound with a 2-hydroxyethylamino substituent demonstrates the highest fluorescence response (up to 60 times) and good range of insulin fibril detection (1-50 μg/ml). In complexes with fibrils, the dyes possess fluorescence quantum yield values up to 15% and binding constant values of about 2 × 105 M-1. The excitation and emission maxima of β-ketoenoles are located in the range 407-427 nm and 500-554 nm correspondingly. These compounds are weakly fluorescent when free and slightly sensitive to the native proteins insulin and bovine serum albumin. Thus β-ketoenoles are considered as prospective molecules for the fluorescent detection of amyloid aggregates of proteins. © 2016 Elsevier Ltd. All rights reserved. Source

Wiesneth S.,Universitatsstr 31 | Petereit F.,Institute of Pharmaceutical Biology and Phytochemistry IPBP | Jurgenliemk G.,Universitatsstr 31
Molecules | Year: 2015

In the present study, a qualitative analysis of proanthocyanidins (PAs) from an aqueous-methanolic extract of Salix daphnoides VILL. bark is described. Procyanidin B1 (1), B2 (2), B3 (3), B4 (4), C1 (5), epicatechin-(4β→8)-epicatechin-(4β→8)-catechin (6) and epicatechin-(4β→8)-epicatechin-(4β→8)-epicatechin-(4β→8)-catechin (7) have been isolated by a combination of different chromatographic separations on Sephadex® LH-20-, MCI®-, Diol-and RP-18-phases. Mass spectrometry, 1D- and 2D-NMR, circular dichroism and polarimetry were used for their structure elucidation and verification by comparison with the literature. Additionally, two fractions of very polar flavan-3-ols were compared: "regular" polymeric PAs received at the very end of the Sephadex® LH-20 chromatography showing no mobility on silica TLC and "unusual" PAs with the same RF-value but already eluting together with flavonoids in the Sephadex® LH-20 system. These "unusual" PAs were subsequently enriched by centrifugal partition chromatography (CPC). C-NMR, polarimetry, thiolysis, acid hydrolysis and phloroglucinol degradation were used to characterize both fractions. Differences in the composition of different flavan-3-ol units and the middle chain length were observed. © 2015 by the authors. Source

Bohm C.,Universitatsstr 31 | Lauf W.,Universitatsstr 31
Computational Methods and Function Theory | Year: 2014

We give a generalization of the Komatu–Loewner equation to multiple slits. Therefore, we consider an n-connected circular slit disk Ω as our initial domain minus m ∈ N disjoint, simple and continuous curves that grow from the outer boundary ∂D of Ω into the interior. Consequently, we get a decreasing family (Formula Presented.) of domains with Ω0=Ω. We will prove that the corresponding Riemann mapping functions gt from Ωt onto a circular slit disk, which are normalized by gt(0)=0 and gt'(0)>0, satisfy a Loewner equation known as the Komatu–Loewner equation. © 2014, Springer-Verlag Berlin Heidelberg. Source

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