Constituents of Eupomatia species. The structure and synthesis of eupomatene, a lignan of novel type from Eupomatia laurina R. Br

1969 ◽  
Vol 22 (5) ◽  
pp. 1011 ◽  
Author(s):  
RS McCredie ◽  
E Ritchie ◽  
WC Taylor
Keyword(s):  
Molecular Weight ◽  
Natural Products ◽  
Oxidative Coupling ◽  
Low Molecular Weight ◽  
Dihydro Derivative ◽  
Simple Phenol

The bark of Eupomatia laurina R. Br. yielded the known alkaloid, liriodenine, and four new substances. One of these, eupomatene, was shown by degradation to be 7-methoxy-3-methyl-2-(3?,4?- methylenedioxyphenyl)-5-trans-propenylbenzofuran. The dihydro derivative and eupomatene itself were synthesized. It is proposed that the term ?lignan? be extended to cover all natural products of low molecular weight that arise primarily from the oxidative coupling of p- hydroxyphenylpropene units and that eupomatene be then classified as a lignan. ��� A chlorotropolone has been isolated from a Reimer-Tiemann reaction on a simple phenol.

High concentrations of dissolved oxygen influence the composition of low molecular weight natural compounds in Lake Baikal endemic amphipods

Crustaceana ◽  
2021 ◽  
Vol 94 (4) ◽  
pp. 393-405
Author(s):  
D. V. Axenov-Gribanov ◽  
Y. A. Rzhechitskiy ◽  
M. M. Morgunova ◽  
V. A. Emshanova ◽  
Y. A. Lubyaga ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Molecular Weight ◽  
Natural Products ◽  
Lake Baikal ◽  
Natural Compounds ◽  
High Oxygen ◽  
Low Molecular Weight ◽  
Metabolic Profiles ◽  
High Oxygen Content ◽  
Stress Dependent

Abstract Lake Baikal provides a unique opportunity to study oxyphilic organisms in the focus of their adaptive abilities, and antioxidant potential. The purpose of this study was to estimate the changes in metabolic profiles and reactions of antioxidant capacities in Baikal endemic amphipods to the stress of high oxygen content. As a result of our study we have found that a high level of oxygen in the environment leads to the activation of a specific adaptive response in endemic organisms, which are naturally resistant to short-term increased concentrations of oxygen. Exposing animals to high oxygen concentrations causes both activation, i.e., use, and concurrently apparent inhibition of the synthesis of some low molecular weight natural compounds (whose specific nature is yet to be determined) in these endemic amphipods. This could be explained by the animals’ response to oxidative stress and stress-induced synthesis of natural compounds as adaptation mechanisms. At the same time, the reactions of elimination of some natural products found in metabolic profiles can be explained by the specific reduction of target metabolites or molecules neutralizing oxygen radicals and decreasing their content during exposition to current stress conditions. We also noted species-specific, stress-dependent changes in the antioxidant capacity of amphipods. Thus, the newly described mechanisms of stress resistance and newly found molecules in these endemic crustaceans can become a basis for development of new potential natural products, e.g., drugs, the action of which should be aimed at elimination or at least reduction of oxidative stress in organisms and its undesired consequences.

The Role of Bacterial Natural Products in Predator Defense

Synlett ◽  
2018 ◽  
Vol 29 (05) ◽  
pp. 537-541 ◽  
Author(s):  
Pierre Stallforth ◽  
Martin Klapper ◽  
Johannes Arp ◽  
Markus Günther
Keyword(s):  
Molecular Weight ◽  
Natural Products ◽  
Anticancer Drugs ◽  
Soil Bacteria ◽  
Therapeutic Use ◽  
Low Molecular Weight ◽  
Active Compounds ◽  
Predator Defense ◽  
Predator Prey

Bacterially produced natural products, i.e., low molecular weight metabolites, or derivatives thereof, constitute most of the commercially available antibiotics as well as a large proportion of anticancer drugs. While indispensable as therapeutically active compounds, the ecological roles of many of these bacterial natural products remain poorly understood. Here, we discuss these metabolites in light of ­microbial predator defense: soil bacteria are constantly threatened by a variety of predators and the secretion of low molecular weight toxins enables the producing bacteria to kill or deter the predator. Conversely, a deeper understanding of these microbial predator–prey interactions can lead to the discovery of novel compounds, which in turn can be of therapeutic use.

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Low-molecular-weight heparin in the prevention and treatment of thromboembolic disorders

1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Prevention And Treatment
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