The potential of plant bioactives for the prevention and therapy of diabetes is increasingly being recognized. In the present study we investigated the antidiabetic properties of an aqueous Bistorta ...officinalis Delarbre extract (BODE) by employing both in-vitro assays and in-vivo models. Multiple targets in glucose homeostasis which are involved in the regulation of the blood glucose level were affected by BODE in-vitro. The extract exhibited inhibitory activities towards the intestinal carbohydrate-hydrolysing enzymes α-amylase and α-glucosidase with IC
values of 81.5 μg/mL and 8.4 μg/mL, respectively. Furthermore, moderate reduction of the dipeptidyl peptidase-4 (DPP4) enzyme activity was evident when tested in the presence of 1.0 mg/mL BODE. A significant inhibition of the intestinal glucose transporter sodium-dependent glucose transporter 1 (SGLT1) in response to 1.0 mg/mL BODE was shown for Caco-2 cells mounted in Ussing chambers. High performance liquid chromatography-mass spectrometry analyses of the BODE revealed several plant bioactives including gallotannins, catechins and chlorogenic acid. Although our in-vitro data were promising, BODE-supplementation in the model organism Drosophila melanogaster lacked to confirm the antidiabetic effect of the extract in-vivo. Moreover, BODE failed to reduce blood glucose levels in chicken embryos (in-ovo). Hence, BODE is probably not a suitable candidate for developing a pharmaceutical against diabetes mellitus.
Herein we report on the synthesis and properties of 6,6′-dithienylindigo (DTI), as well as its solubilized N , N ′-di( tert -butoxy carbonyl) derivative ( t BOC-DTI). t BOC-DTI can be ...electropolymerized and thermally interconverted into films of poly(DTI). Thin films of DTI afford quasi-reversible 2-electron reduction and oxidation electrochemistry, and demonstrate ambipolar charge transport in organic field-effect transistors with a hole mobility of up to 0.11 cm 2 V −1 s −1 and an electron mobility of up to 0.08 cm 2 V −1 s −1 . Operation of the p-channel shows excellent air stability, with minimal degradation over a 60 day stressing study. Poly(DTI) can be reversibly oxidized and reduced over hundreds of cycles while remaining immobilized on the working electrode surface, and additionally shows a pronounced photoconductivity response in a diode device geometry. This work shows the potential of extended indigo derivatives for organic electronic applications, demonstrating impressive stability under ambient conditions.
The thermally assisted hydrolysis and methylation (THM) analysis of glycolaldehyde produces a series of methylated C3 to C6 metasaccharinic acids by aldol reactions. The contribution of aldol and ...retro aldol reactions was investigated by analysis of 1-
13C-glycolaldehyde, 1-
13C-glucose, and 6-
13C-glucose. It could be shown that carbohydrates undergo retro aldol cleavage under strong alkaline conditions, as they are in THM, and that these cleavage products subsequently produce higher molecular weight condensation products by aldol reactions. The cleavage occurs more readily close to the reducing end of the carbohydrate and recombination of these fragments may account for up to 30% of the saccharinic acid products formed.
The thermally assisted hydrolysis and methylation (THM) reaction of hexuronic acids and xylobiose using tetramethylammonium hydroxide (TMAH) was studied. The results were compared to the THM of the ...corresponding matrix polymers. Glucuronic and galacturonic acids—which we take as model substances—produce unique products, namely 2,4,6-tri-
O-methyl-3-deoxy-glucaric acid dimethyl ester and tri-
O-methyl-3-deoxy-galactaric acid dimethyl ester, respectively, together with their epimers. The EI mass spectrum, as well as a proposed fragmentation pathway, are presented. These markers, however, are not detectable in the THM of the corresponding polymers, i.e. the hemicellulose xylan and pectin.
Etherified melamine resins are well known from the lacquer and paint industry. Up to now, important characterization in terms of composition and structure has been a time-consuming procedure. Now, ...fast analysis can also be achieved by use of
13
C nuclear magnetic resonance spectroscopy. A special polarization transfer technique was applied to overcome the inherent low signal/noise ratio of
13
C NMR spectra. The melamine content of the resin was determined by combustion analysis. This combination of methods allows for fast resin analysis with accuracy as yet unmatched and shows good correlation with established techniques.
Among several other carbohydrates, especially glyceraldehyde yields some high molecular weight condensation products in thermally assisted hydrolysis and methylation (THM). Besides the fully ...methylated saccharinic acids and their degradation products, which are already known from the THM of simple carbohydrates, partially methylated metasaccharinic acid methyl esters (3-deoxy-4,5,6-tri-
O-methylhexonic acid methyl ester) and methylated metasaccharinolactones (3-methoxy-5-(1,2-dimethoxyethyl)-tetrahydrofuran-2-one) could be identified. The corresponding methylated derivatives of isosaccharinic acid (3-deoxy-2-methoxymethyl-4,5-di-
O-methylpentonic acid methyl ester and 3-methoxy-3,5-bismethoxymethyltetrahydrofuran-2-one) were found in the THM analysis of cellulose. Identity of the products was confirmed by EI and CI mass spectrometry and synthesis of the products via the Ca-salts of metasaccharinic and isosaccharinic acid.
Cellulose is being derivatized to change its properties and improve usability for special purposes. Its esters with phthalic acid, citric acid, maleic acid, and nitric acid were examined with ...analytical pyrolysis and thermally assisted hydrolysis and methylation using tetramethylammonium hydroxide. With traditional analytical pyrolysis the free acid or an anhydrous and decarboxylated thermally stable form could be proved in organic cellulose esters with a low degree of substitution, whereas for the high substituted cellulose nitrate also completely new products were produced through this method. Using thermally assisted hydrolysis and methylation the sensitivity of the method could be improved especially for cellulose derivatives with a low degree of substitution and characteristic products could be identified for most samples.
