ChemInform Abstract: Regioselective Generation of Iminium Cation by PET Processes: Its in situ Trapping by Intramolecular Nucleophiles and Synthesis of Some Biologically Active Heterocycles.

ChemInform ◽  
2010 ◽  
Vol 24 (1) ◽  
pp. no-no
Author(s):  
G. PANDEY ◽  
G. KUMARASWAMY ◽  
P. Y. REDDY
Keyword(s):  
Biologically Active

CHANGES IN THE VANADIUM MIGRATION FORMS ON GEOCHEMICAL BARRIERS IN THE RIVER-SEA MIXING ZONES

2021 ◽  
Author(s):  
Victoria Khoroshevskaya
Keyword(s):  
Software Package ◽  
Sorption Process ◽  
Biologically Active ◽  
Software Systems ◽  
River Waters ◽  
Geochemical Barriers ◽  
Physicochemical Processes ◽  
Estuarine Zone ◽  
Associative Models

The article is devoted to the study of vanadium, a metal capable of stimulating the growth of phytoplankton in situ and has the greatest biological activity in dissolved form. The pattern of an increase in the concentration of vanadium dissolved forms in the mixing zones during the transition from river waters to seawaters is known. In this article, we examine the behavior, ratio and change in the concentrations of vanadium dissolved and suspended forms during the passage of geochemical barriers. The estuarine zone of the Razdolnaya River–Amur Bay (Sea of Japan) is considered as "river-sea" mixing zone. Modelling of physicochemical processes was carried out using the Selector-S and MINTEQA2/PRODEFA2 software systems. Ion-associative models of sea and river water were built and the modelling of the process of their mixing was carried out using the Selector-S software package. The sorption process was simulated using the MINTEQA2/PRODEFA2 software package. The results of modelling physicochemical processes occurring at geochemical barriers help to understand the reasons for changes in concentrations, both total vanadium and biologically active dissolved vanadium forms, during the passage of geochemical barriers in the "river-sea" mixing zones. The results showed that there is a change in the dissolved forms of vanadium migration, their transformation and an increase in the concentration of dissolved forms of vanadium at the geochemical barrier

scholarly journals Imaging Sterols and Oxysterols in Mouse Brain Reveals Distinct Spatial Cholesterol Metabolism

2018 ◽  
Author(s):  
Eylan Yutuc ◽  
Roberto Angelini ◽  
Mark Baumert ◽  
Natalia Mast ◽  
Irina Pikuleva ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Mouse Brain ◽  
Brain Function ◽  
Mass Spectrometry Imaging ◽  
Cholesterol Metabolism ◽  
Biologically Active ◽  
Wild Type ◽  
Tissue Slices ◽  
The Brain

AbstractDysregulated cholesterol metabolism is implicated in a number of neurological disorders. Many sterols, including cholesterol and its precursors and metabolites, are biologically active and important for proper brain function. However, spatial cholesterol metabolism in brain and the resulting sterol distributions are poorly defined. To better understand cholesterol metabolism in situ across the complex functional regions of brain, we have developed on-tissue enzyme-assisted derivatisation in combination with micro-liquid-extraction for surface analysis and liquid chromatography - mass spectrometry to image sterols in tissue slices (10 µm) of mouse brain. The method provides sterolomic analysis at 400 µm spot diameter with a limit of quantification of 0.01 ng/mm2. It overcomes the limitations of previous mass spectrometry imaging techniques in analysis of low abundance and difficult to ionise sterol molecules, allowing isomer differentiation and structure identification. Here we demonstrate the spatial distribution and quantification of multiple sterols involved in cholesterol metabolic pathways in wild type and cholesterol 24S-hydroxylase knock-out mouse brain. The technology described provides a powerful tool for future studies of spatial cholesterol metabolism in healthy and diseased tissues.SignificanceThe brain is a remarkably complex organ and cholesterol homeostasis underpins brain function. It is known that cholesterol is not evenly distributed across different brain regions, however, the precise map of cholesterol metabolism in the brain remains unclear. If cholesterol metabolism is to be correlated with brain function it is essential to generate such a map. Here we describe an advanced mass spectrometry imaging platform to reveal spatial cholesterol metabolism in situ at 400 µm resolution on 10 µm tissue slices from mouse brain. We mapped, not only cholesterol, but also other biologically active sterols arising from cholesterol turnover in both wild type and mice lacking cholesterol 24-hydroxylase (Cyp46a1), the major cholesterol metabolising enzyme.

Highly Selective One-Pot Synthesis of Polysubstituted Isoflavanes using Styryl Ethers and Electron-Withdrawing ortho-Quinone Methides Generated In Situ

Synlett ◽  
2018 ◽  
Vol 30 (02) ◽  
pp. 189-192 ◽  
Author(s):  
Yujiro Hoshino ◽  
Kiyoshi Honda ◽  
Kenta Tanaka ◽  
Mami Kishimoto ◽  
Naoya Ohtsuka ◽  
...  
Keyword(s):  
Biologically Active ◽  
Quinone Methides ◽  
One Pot ◽  
One Pot Synthesis ◽  
Reaction Proceeds ◽  
Acidic Conditions ◽  
High Yields

A highly selective one-pot synthesis of polysubstituted isoflavanes has been developed. The reaction proceeds through the cycloaddition of methyl styryl ethers, derived from phenylacetaldehyde dimethyl acetals under acidic conditions, with electron-withdrawing ortho-quinone methides generated in situ. When phenylacetaldehyde dimethyl acetals were reacted with salicylaldehydes, the reaction proceeded smoothly to afford the corresponding isoflavanes stereoselectively in high yields and with excellent regioselectivities. The present reaction provides versatile access to functionalized isoflavanes, and constitutes a useful tool for the synthesis of biologically active molecules.

Minor enantiomer recycling – a strategy to improve enantioselectivity

2016 ◽  
Vol 88 (4) ◽  
pp. 309-316 ◽  
Author(s):  
Christina Moberg
Keyword(s):  
Catalytic Reaction ◽  
Enantiomeric Purity ◽  
Biologically Active Compounds ◽  
Starting Material ◽  
Biologically Active ◽  
Active Compounds ◽  
Enantioselective Reactions

AbstractIn enantioselective reactions, the major, desired enantiomer is commonly obtained along with the minor, undesired enantiomer. By continuous recycling of this undesired enantiomer back to starting material, products with improved enantiomeric purity can be obtained. Such in situ minor enantiomer recycling can be accomplished by coupling the catalytic reaction to an exergonic transformation of a sacrificial reagent. The method has been applied to the synthesis of O-acylated cyanohydrins, which serve as starting materials for a variety of biologically active compounds.

scholarly journals Recent Advances in the Synthesis of Isothiocyanates Using Elemental Sulfur

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1081
Author(s):  
András Gy. Németh ◽  
Péter Ábrányi-Balogh
Keyword(s):  
Natural Products ◽  
Best Practices ◽  
Organic Synthesis ◽  
Elemental Sulfur ◽  
Biologically Active ◽  
Primary Amines ◽  
Pharmaceutical Ingredients ◽  
Recent Developments ◽  
In Situ Generation

Isothiocyanates (ITCs) are biologically active molecules found in several natural products and pharmaceutical ingredients. Moreover, due to their high and versatile reactivity, they are widely used as intermediates in organic synthesis. This review considers the best practices for the synthesis of ITCs using elemental sulfur, highlighting recent developments. First, we summarize the in situ generation of thiocarbonyl surrogates followed by their transformation in the presence of primary amines leading to ITCs. Second, carbenes and amines afford isocyanides, and the further reaction of this species with sulfur readily generates ITCs under thermal, catalytic or basic conditions. Additionally, we also reveal that in the catalyst-free reaction of isocyanides and sulfur, two—until this time overlooked and not investigated—different mechanistic pathways exist.

scholarly journals Highly Diastereoselective Synthesis of Tetrahydroquinoline Derivatives via [4 + 2] Annulation of Ortho-Tosylaminophenyl-Substituted Para-Quinone Methides and Cyanoalkenes

2021 ◽  
Vol 9 ◽  
Author(s):  
Taiwei Dong ◽  
Peifeng Wei ◽  
Min Li ◽  
Feng Gao ◽  
Yuan Qin
Keyword(s):  
Biologically Active ◽  
Structural Motif ◽  
Diastereoselective Synthesis ◽  
Atom Economy ◽  
Quinone Methides ◽  
One Pot ◽  
Reaction Performance ◽  
High Yields ◽  
Active Natural

As a privileged structural motif, tetrahydroquinoline skeletons widely exist in biologically active natural products and pharmaceuticals. In this protocol, a highly diastereoselective [4 + 2] annulation of ortho-tosylaminophenyl-substituted p-QMs and cyanoalkenes to construct tetrahydroquinoline derivatives has been successfully achieved. This strategy proceeds efficiently under mild condition, offering straightforward route to a variety of 4-aryl-substituted tetrahydroquinolines with high yields, excellent diastereoselectivities, broad functional group tolerance as well as gram-scale capacity. Moreover, a one-pot reaction sequence utilizing in situ generated p-QMs under the similar condition to build tetrahydroquinoline framework is smoothly conducted with good reaction performance as well as step and atom economy.

Peripheral metabolism of PTH: fate of biologically active amino terminus in vivo

1988 ◽  
Vol 255 (6) ◽  
pp. E886-E893 ◽  
Author(s):  
F. R. Bringhurst ◽  
A. M. Stern ◽  
M. Yotts ◽  
N. Mizrahi ◽  
G. V. Segre ◽  
...  
Keyword(s):  
Specific Activity ◽  
Limited Proteolysis ◽  
High Specific Activity ◽  
Biologically Active ◽  
Amino Terminal ◽  
Liver And Kidney ◽  
Low Levels ◽  
Peripheral Metabolism

Clearance of intact parathyroid hormone (PTH) from blood is associated with rapid uptake by liver and kidney, limited proteolysis by tissue endopeptidases and, within minutes, appearance of circulating carboxyl-(COOH)-terminal PTH fragments. The fate of the corresponding amino(NH2)-terminal portion of the hormone during this peripheral metabolism is still unknown, however. To determine this, we have employed [35S]bovine PTH (bPTH) labeled to high specific activity at NH2-terminal methionines, which permits direct monitoring of the fate of the PTH NH2-terminus during metabolism in vivo. The [35S]PTH was administered by bolus or continuous intravenous infusion to anesthetized normal rats, to rats subjected to acute ablation of the liver, the kidneys, or both, and to rats receiving co-infusions of excess synthetic bPTH(1-34) NH2-terminal fragments. Analysis by high-resolution chromatographic techniques sensitive to 10(-13) M [35S]PTH peptides in plasma yields no evidence that peripheral metabolism of PTH generates circulating NH2-terminal fragments, even when special measures are taken to block clearance of such putative fragments from blood. We find that the NH2-terminus of PTH is rapidly degraded in situ by the liver but that both liver and especially kidney nevertheless contain low levels of NH2-terminal PTH fragments that, although not released into the blood, are large enough to be potentially active. Thus, the peripheral metabolism of PTH in normal animals does not normally lead to the formation of circulating amino terminal fragments of the hormone that might act independently of intact PTH on peripheral target tissues.

scholarly journals In Situ Bioremediation Techniques to Reduce Total Organic Matter Oversaturation of Fluvial Sediments: An Experimental Study

2020 ◽  
Vol 10 (12) ◽  
pp. 4308
Author(s):  
Carlos Rochera ◽  
Antonio Picazo ◽  
Nayeli Murueta ◽  
Antonio Camacho
Keyword(s):  
Organic Matter ◽  
Anaerobic Respiration ◽  
Electron Acceptors ◽  
Biologically Active ◽  
Inorganic Nutrients ◽  
Limiting Factors ◽  
Bacterial Strains ◽  
In Situ Experiment ◽  
Significant Drop

An in situ experiment was performed in sediments of River Magro (east Spain) in order to evaluate the usefulness of microbial bioremediation, both bioaugmentation and biostimulation, as a tool for reducing the excessive organic matter (OM) content in dammed river stretches due to historical wastewater spilling. The study had a prospective approach focused on the application of a biologically active commercial product (BAP), consisting of a mix of bacterial strains, ectoenzymes, and nutrients, where a range of concentrations and temporal dosages of the product were experimentally assayed in situ. They were further combined with the addition of potential organic enhancers, such as acetate, as well as of inhibitors of specific microbial guilds. On the other hand, inorganic electron acceptors for the anaerobic respiration of the organic matter were additionally amended. In additional assays, the BAP additions were combined with inorganic nutrients amendments, or even the latter were tested alone. These combinative treatments aimed at exploring the possible enhancement of synergistic or antagonistic interactions among the amended compounds, as well as the eventual effect of growth limiting factors. The single BAP additions of 50 g/m3 led to OM reductions of up to 17%, and significant removals of nitrogen or phosphorus were additionally observed by increasing or by fractioning the BAP dosage, respectively. However, a better response using the same amount of the BAP was obtained by supplementing it with sodium acetate. In this case, reductions of the OM content reached up to 35% of the accumulated OM, thus indicating that a complementary stimulus is still necessary to run out barriers towards the final steps of the anaerobic OM digestion. This treatment was also linked to the strongest significant drop in the TP content of the sediments. Neither the addition of inorganic electron acceptors nor inorganic nutrients improved the results, or they were even antagonistic of the degradative potential of the BAP product. Apparently, the occurrence of acetoclastic microorganisms, which was demonstrated by high throughput DNA-sequencing, was critical for the optimal OM reductions in the sediments. This exploratory study demonstrates that the applicability of BAPs can be extended to cover the remediation of fluvial ecosystems, and support the complementarity of different bioremediation strategies.

Relationships between atmospheric organic compounds and air-mass exposure to marine biology

2010 ◽  
Vol 7 (3) ◽  
pp. 232 ◽  
Author(s):  
S. R. Arnold ◽  
D. V. Spracklen ◽  
S. Gebhardt ◽  
T. Custer ◽  
J. Williams ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Organic Compounds ◽  
Marine Biology ◽  
Transport Model ◽  
Oxidative Capacity ◽  
South Atlantic ◽  
Biologically Active ◽  
South Atlantic Ocean ◽  
Air Mass

Environmental context.The exchange of gases between the atmosphere and oceans impacts Earth’s climate. Over the remote oceans, marine emissions of organic species may have significant impacts on cloud properties and the atmosphere’s oxidative capacity. Quantifying these emissions and their dependence on ocean biology over the global oceans is a major challenge. Here we present a new method which relates atmospheric abundance of several organic chemicals over the South Atlantic Ocean to the exposure of air to ocean biology over several days before its sampling. Abstract.We have used a Lagrangian transport model and satellite observations of oceanic chlorophyll-a concentrations and phytoplankton community structure, to investigate relationships between air mass biological exposure and atmospheric concentrations of organic compounds over the remote South Atlantic Ocean in January and February 2007. Accounting for spatial and temporal exposure of air masses to chlorophyll from biologically active ocean regions upwind of the observation location produces significant correlations with atmospheric organohalogens, despite insignificant or smaller correlations using commonly applied in-situ chlorophyll. Strongest correlations (r = 0.42–0.53) are obtained with chlorophyll exposure over a 2-day transport history for CHBr3, CH2Br2, CH3I, and dimethylsulfide, and are strengthened further with exposure to specific phytoplankton types. Incorporating daylight and wind-speed terms into the chlorophyll exposure results in reduced correlations. The method demonstrates that conclusions drawn regarding oceanic trace-gas sources from in-situ chlorophyll or satellite chlorophyll averages over arbitrary areas may prove erroneous without accounting for the transport history of air sampled.

Sign in / Sign up

Export Citation Format

Share Document