Search results for "LENI"
showing 10 items of 756 documents
Trapping Rare and Elusive Phosphinidene Chalcogenides
2017
Four-membered rings with a P2Ch2 core (Ch=S, Se) and phosphorus in the +3 oxidation state have been synthesized. The utility of these rings as a source of monomeric phosphinidene chalcogenides was probed by the addition of an N-heterocyclic carbene, resulting in a base-stabilized phosphinidene sulfide. Similarly, persistence of the phosphinidene selenide in solution was shown through cycloaddition chemistry with 2,3-dimethylbutadiene at elevated temperatures. The observed reactivity was explained by detailed computational work that established the conditions upon which the P2Ch2 rings can liberate phosphinidene chalcogenides. peerReviewed
Selenium Partitioning and Stable Isotope Ratios in Urban Topsoils
2011
oxides. Th e δ82/76 Se values of total Se in the topsoils were close to the bulk Earth composition with an average δ82/76 Se value of −0.03 ± SD 0.38‰ suggesting that there was no or little Se isotope fractionation in soil. We attribute the small isotope fractionation to the low bioavailability of Se as a consequence of the presence of Fe oxides (adsorbing the dominating Se(IV) forms strongly), organic matter, and SO 4 2− (prevents biouptake of the Se(IV) forms) in the study soils. Small Se isotope fractionations of −0.59 to −0.35‰ in mainly forest soils and of 0.26 to 0.45‰ in mainly alluvial soils were presumably caused by soil/plant-recycling and Se contamination by river water, respecti…
Unsaturated fatty acid bioavailability in growing rats fed low or adequate protein diets with sunflower or soybean oils
1993
Abstract The relationship of serum very low density lipoproteins (VLDL) to hepatic lipid composition was studied after 28 days of protein depletion to determine the interactions between dietary protein levels and the essential fatty acid (EFA) availability. This was examined in rats using a dietary combination of 20% or 2% casein with 5% vegetable oils, variable in their n-6:n-3 fatty acid ratios. Rats were divided into four groups, SFC (20% casein + 5% sunflower oil ); SFd (2% casein + 5% sunflower oil ); SC (20% casein + 5% soybean oil ); Sd (2% casein + 5% soybean oil ). Dietary protein depletion decreased phospholipid and protein concentrations in liver and VLDL, whereas triacylglycerol…
Revisiting delta-6 desaturase regulation by C18 unsaturated fatty acids, depending on the nutritional status.
2009
Dietary polyunsaturated fatty acids (PUFA) play a key role in regulating delta-6 desaturase (D6D), the key enzyme for long-chain PUFA biosynthesis. Nevertheless, the extent of their effects on this enzyme remains controversial and difficult to assess. It has been generally admitted that C18 unsaturated fatty acids (UFAs) regulate negatively delta-6 desaturase (D6D). This inhibition has been evidenced in regard to a high glucose/fat free (HG/FF) diet used in reference. However, several nutritional investigations did not evidence any inhibition of desaturases when feeding fatty acids. Because the choice of the basal diet appeared to be of primary importance in such experiments, our goal was t…
Non-hydrolysable macromolecular constituents from outer walls of Chlorella fusca and Nanochlorum eucaryotum
1992
Abstract Many green microalgae possess a thin trilaminar outer wall (TLS) with a very high resistance to chemical degradation. TLS are known to play an important protective role in living cells. They are also selectively preserved during fossilization and thus provide a major contribution to the fossil organic matter of a number of sedimentary rocks. However, little information is available on TLS chemical structure. Examination of the TLS of Chlorella fusca (a lacustrine Chlorophycea) and of Nanochlorum eucaryotum (a recently discovered marine Chlorophycea) indicated that (i) they exhibit morphological features commonly observed in other green microalgae, (ii) their non-hydrolysable macrom…
Enzymatic Biosynthesis of Vomilenine, a Key Intermediate of the Ajmaline Pathway, Catalyzed by a Novel Cytochrome P 450-Dependent Enzyme from Plant C…
1995
Abstract Microsomal preparations from Rauwolfia serpentina Benth. cell suspension cultures catalyze a key step in the biosynthesis of ajmaline -the enzymatic hydroxylation of the indole alkaloid vinorine at the allylic C-21 resulting in vomilenine. Vomilenine is an important branch-point intermediate, leading not only to ajmaline but also to several side reactions of the biosynthetic pathway to ajmaline. The investigation of the taxonomical distribution of the enzyme indicated that vinorine hydroxylase is exclusively present in ajmaline-producing plant cells. The novel enzyme is strictly dependent on NADPH2 and O2 and can be inhibited by typical cytochrome P450 inhibitors such as cytochrom…
Fatty acid composition of a cultured sturgeon hybrid (×)
2005
Abstract Analyses of fatty acids from the dorsal muscle of Acipenser naccarii × A. baerii sturgeon hybrid were carried out. The data were compared with those reported in the literature for other sturgeons reared for human consumption. This hybrid would seem to be of great nutritional interest, its flesh being more beneficial for human health than those of other cultured sturgeons. In fact, the level of polyunsaturated fatty acids (PUFAs) was very high (34.7 ± 0.67%), being similar to that of monounsaturated fatty acids (37.9 ± 0.83%). Moreover, the PUFAs- n 3/PUFAs- n 6 ratio (6.74) was noticeably higher in this hybrid than in the other cultured sturgeon species. There were also high cont…
An Uncommon Pathway in the Biosynthesis of Acetylenic Fatty Acids in Mosses
1995
Although more than 600 acetylenic compounds of various structures have been found in plants [1], hardly anything is known about the formation of the triple bonds. The acetylenes so far known from Bryophytes, have been identified as long chain fatty acids with a characteristic arrangement of one triple bond and one to three double bonds.
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.
Platelet and Plasmatic Lipidic Profile as Potential Marker of Bipolar Disorders: Preliminary Findings
2017
IntroductionAlthough the diagnosis of bipolar disorder is currently based on clinical criteria, preliminary studies showed that palmitic and arachidonic acid levels are able to discriminate adult patients with major depressive disorder (MDD) from those with bipolar disorder (BD).ObjectivesTo replicate and to expand previous findings by investigating the relation between mood disorders and platelet and plasmatic fatty levels.AimsTo compare the lipidic profile of individuals with different mood disorder (MDD vs. BD) and to investigate the relation with specific clinical features (duration of illness, attempted suicide, psychotic symptoms).MethodsPotential participants were recruited from the …