Search results for "OXIDATION"
showing 10 items of 1913 documents
Über die synthese von oligophenylenes mit einer o-verknüpfung. 10. Mitteilung
1960
Es werden zwei Wege zur Darstellung von Oligophenylenen mit einer o-Winkelung beschrieben. Als Ausgangssubstanzen dienen der Mono-enolather des Cyclohexandion (1,2) bzw. Cyclohexenoxyd. Die Darstellung des Mono-enolathylathers des Cyclohexandion (1,2) wird beschrieben. Durch Oxydation nach OPPENAUER mit Chinon als Wasserstoffacceptor konnen die als Zwischenprodukte der Oligophenylene erhaltenen Cyclohexanolderivate in 90%iger Ausbeute in die benotigten Ketone ubergefuhrt werden. Folgende o-gewinkelten Oligophenylene wurden synthetisiert : o-Terphenyl; 2o2-Quater-phenyl ; 32, 43-Dimethyl-2o2-quaterphenyl ; 3o2-Quinquiphenyl ; 12, 23-Dimethyl-3o2-quinquiphenyl ; 12, 23, 42, 53-Tetramethyl-3o2…
Mo-Based Oxidizers as Powerful Tools for the Synthesis of Thia- and Selenaheterocycles.
2019
A highly efficient synthetic protocol for the synthesis of thia- and selenaheterocycles has been developed. By employing a MoCl5 -mediated intramolecular dehydrogenative coupling reaction, a broad variety of structural motifs was isolated in yields up to 94 %. The electrophilic key transformation is tolerated by several labile moieties like halides and tertiary alkyl groups. Due to the use of disulfide or diselenide precursors, a high atom efficiency was achieved.
Enzymatic Resolution of 3-oxodicyclopentadiene on a Decagram Scale
2018
The chiral building block 3-oxodicyclopentadiene (1) can be readily resolved on a decagram scale by a short sequence consisting of (1) reduction to the corresponding endo-alcohol, (2) enzymatic oxidative resolution with a ketoreductase enzyme to give (+)-1 and the (+)-form of the endo-alcohol, and (3) reoxidation of the (+)-endo-alcohol with another ketoreductase to give (–)-1. With a selectivity factor of 310, the enantiomeric ratios of the resolved (+)-endo-alcohol and (+)-ketone are both >99:1. Both enzymatic oxidations could be performed with a at least 300:1 substrate/catalyst ratio (w/w).
Utilization of different dietary lipid sources at high level in herbivorous grass carp (Ctenopharyngodon idella): mechanism related to hepatic fatty …
2008
Herbivorous grass carp (Ctenopharyngodon idella) has been reported to exhibit low capacity to utilize high dietary lipid, but different lipid sources might affect this limited capacity. In order to compare the effects of different lipid sources with different lipid levels, juvenile grass carp were fed one of nine diets containing three oils [lard, plant oil mixed by maize and linseed oil, and n-3 high unsaturated fatty acid-enriched (HUFA-enriched) fish oil] at three lipid levels (20, 60 and 100 g kg(-1) dry diet) for 8 weeks. Decreased feed intake, poor growth performance, hepatic pathology and higher blood lipid peroxidation were found in 60 and 100 g kg(-1) fish oil groups. Conversely, i…
Enhancing Selectivity In Photocatalytic Formation Of P-Anisaldehyde In Aqueous Suspension Under Solar Light Irradiation Via Tio2 N-Doping
2012
The photocatalytic partial oxidation of 4-methoxybenzyl alcohol to the corresponding aldehyde (p-anisaldehyde) was performed under simulated solar irradiation by using home prepared N-doped TiO2 catalysts. The photocatalysts were prepared by a sol–gel method, using TiCl4 as TiO2 precursor and NH4Cl, urea or NH4OH as N-doping sources. A commercial TiO2 (Degussa P25) was also used for comparison aims. The prepared catalysts were characterized by BET specific surface area, XRD, ESEM and UV-vis spectroscopy. The reactivity results show that (i) the doped catalysts are predominantly amorphous, and they show selectivity values far higher than those of the corresponding undoped ones and of well cr…
Age-related changes in antioxidant status and oxidative damage to lipids and dna in mitochondria of rat liver
2005
To investigate the correlation between oxidative stress and mitochondrial damage with aging, antioxidant system, levels of oxidative DNA damage and as an index of the loss of plasma membrane integrity lipid peroxidation and membrane potential were studied. Results showed that the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase significantly decreased during aging, however glutathione peroxidase (GSH-PX) increased in the aged mitochondria and glutathione (GSH) did not change during aging. No statistical difference was observed in the lipid peroxidation of mitochondria between young and old animals. The level of oxidative DNA damage (measured as 8oxo-dG) tended to in…
Early reductive stress followed by a late onset oxidative stress in acute myocardial infarction
2018
Introduction The idea that the cells might suffer from reductive rather than oxidative stress and that such stress may be relevant in pathophysiology has gained momentum. Aim We aimed at studying markers of oxidative stress and damage as well as the expression of antioxidant enzymes in a swine model of acute myocardial infarction (AMI) followed by reperfusion. Results and Discussion We found an increase in the GSH to GSSG ratio, a decrease in protein glutathionylation and a decrease in p38 MAPK phosphorylation after 90 minutes of ischaemia in heart samples. It was accompanied by an increase in the expression of Thioredoxin (TrX) and Peroxiredoxin (PrX) and a decrease in the expression of Gl…
G6PD Overexpression Protects Mice Against Associated Oxidative Stress and Delays the Occurrence of Frailty
2016
To assess the impact of lifelong overexpression of G6PD on reactive oxygen species (ROS)-derived damage and the prevention of frailty, we measured the levels of macromolecular oxidative damage in young and old mice and the we tested the neuromuscular fitness and the grip strength in old mice. Old G6PD-Tg male and female mice showed diminished accumulation of DNA oxidation (measured as 8-hydroxyguanosine or 8-OHdG) in liver and brain. Old females also showed reduced lipid oxidation (measured as malondialdehyde or MDA) in the liver. Old G6PD-Tg males, but not females, presented a small but significant increase in brain protein carbonylation. In accordance with these findings, liver from 2-yea…
Mechanisms of Glial Swelling by Arachidonic Acid
1994
The effect of arachidonic acid (AA, 20:4) was analyzed in vitro by employment of C6 glioma cells and astrocytes from primary culture. The cells were suspended in an incubation chamber under continuous control of pH, pO2, and temperature. Cell swelling was quantified by flow cytometry. After a control period, the suspension was added with AA at concentrations of 0.01 to 1.0 mM. Administration of AA induced an immediate, dose dependent swelling in C6 glioma cells or astrocytes. AA-concentrations of 0.01 mM led to an increase of the glial cell volume to 103.0 ± 1.0% of control, 0.1 mM to 110.0 ± 1.5%, and l.0 mM to 118.8 ± 1.5% within 10 min. The swelling response to linoleic acid (18 : 2) was…
Natural compounds as light stabilizer for a starch-based biodegradable polymer
2014
Abstract The photooxidation behavior of a commercial starch-based biodegradable polymer, i.e., new generation Mater-Bi, loaded with natural stabilizers was investigated in consideration for outdoor agricultural applications. The photooxidation behavior of the biodegradable films was monitored mainly by mechanical tests and spectroscopic analysis. In order to formulate biodegradable films without any synthetic compounds, suitable for outdoor applications and with good photooxidation stability, antioxidants such as α-tocopherol and quercetin (Q) were considered. The results obtained using natural compounds were compared with those obtained by using a synthetic antioxidant and a light stabiliz…