scholarly journals Relayed magnetization transfer from nuclear Overhauser effect and chemical exchange observed by in vivo 31P MRS in rat brain

2012 ◽  
Vol 30 (5) ◽  
pp. 716-721 ◽  
Author(s):  
Fei Du ◽  
Yi Zhang ◽  
Wei Chen
Keyword(s):  
Rat Brain ◽  
Chemical Exchange ◽  
Nuclear Overhauser Effect ◽  
Magnetization Transfer ◽  
31P Mrs ◽  
Overhauser Effect ◽  
Nuclear Overhauser

A stereodynamic investigation of antivitamins K in the dicoumarol series. II. Differentiation between the two hydroxyl groups by the nuclear Overhauser effect

1976 ◽  
Vol 54 (5) ◽  
pp. 813-816 ◽  
Author(s):  
Claude Laruelle ◽  
Jean-Jacques Godfroid
Keyword(s):  
Chemical Exchange ◽  
Nuclear Overhauser Effect ◽  
Hydroxyl Groups ◽  
Hindered Rotation ◽  
Interatomic Distances ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
A Site ◽  
Hydroxyl Protons ◽  
Antivitamins K

Dicoumarol derivatives, substituted at the bridgehead, show a double restricted rotation. This hindered rotation is manifest through the appearance of two signals, the hydroxyl protons being diastereotopic at low temperatures.In this work we assign the two respective signals by the nuclear Overhauser effect. The high-field signal corresponds to a hydroxyl site close to the bridgehead tertiary proton, while the other corresponds to a site in proximity to the substituent R. The case of structurally analogous dimethones has been investigated by the same technique with identical conclusions. This disproves the interpretation made previously on the basis of steric and anisotropic effects.The interatomic distances concerned have been calculated, and these have yielded an estimate of deformations induced by the bridgehead substituents.Evidence is supplied for the different behavior of the two sites and this study gives evidence for a very facile intermolecular chemical exchange of the hydroxyl site close to the tertiary bridgehead proton in the presence of traces of protonated compounds.The overall behavior is the result of the asymmetry of the molecules of this series in their chelated form.

In vivo nuclear overhauser effect in31P- {1H} double-resonance experiments in a 1.5-T whole-body MR system

1990 ◽  
Vol 15 (1) ◽  
pp. 165-172 ◽  
Author(s):  
P. Bachert-Baumann ◽  
F. Ermark ◽  
H.-J. Zabel ◽  
R. Sauter ◽  
W. Semmler ◽  
...  
Keyword(s):  
Nuclear Overhauser Effect ◽  
Double Resonance ◽  
Whole Body ◽  
Overhauser Effect ◽  
Nuclear Overhauser

1H NMR studies of [N-MeAib1, Tyr(Me)4]ANGII and [N-MeAib1, Tyr(Me)4, Ile8]ANGII in dimethylsulfoxide by nuclear Overhauser effect (NOE) enhancement spectroscopy: cis-trans Isomerism of the His-Pro bond

1990 ◽  
Vol 55 (4) ◽  
pp. 1106-1111 ◽  
Author(s):  
John Matsoukas ◽  
Paul Cordopatis ◽  
Raghav Yamdagni ◽  
Graham J. Moore
Keyword(s):  
1H Nmr ◽  
Nuclear Overhauser Effect ◽  
Nmr Studies ◽  
Restricted Rotation ◽  
Overhauser Effect ◽  
Major Isomer ◽  
Conformational Properties ◽  
Nuclear Overhauser

The conformational properties of the Sarmesin analogues [N-MeAib1, Tyr(Me)4]ANGII and [N-MeAib1, Tyr(Me)4, Ile8]ANGII in hexadeutero-dimethysulfoxide were investigated by Nuclear Overhauser Effect (NOE) Enhancement Studies. Cis-trans isomers (ratio 1 : 6) due to restricted rotation of the His-Pro bond were observed. Interresidue interactions between the His Cα proton and the two Pro Cδ protons revealed that the major isomer was the trans.

scholarly journals Cylindromicin from Arctic-Derived Fungus Tolypocladium sp. SCSIO 40433

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1080
Author(s):  
Imran Khan ◽  
Jing Peng ◽  
Zhuangjie Fang ◽  
Wei Liu ◽  
Wenjun Zhang ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Nuclear Overhauser Effect ◽  
Inhibition Activity ◽  
Tyrosinase Inhibition ◽  
Bioactive Natural Products ◽  
Chemical Structures ◽  
Overhauser Effect ◽  
Spectroscopic Analyses ◽  
Potential Resource ◽  
Nuclear Overhauser

The fungus strain SCSIO 40433 was isolated from an Arctic-derived glacier sediment sample and characterized as Tolypocladium cylindrosporum. A new compound, cylindromicin (1), and seven known secondary metabolites (2–8) were isolated from this strain. The chemical structures of these compounds were elucidated by comprehensive spectroscopic analyses. Cylindromicin (1) featured a 3,4-dihydro-2H-pyran skeleton. The absolute configuration of compound 1 was assigned via interpretation of key Nuclear Overhauser Effect Spectroscopy (NOESY) correlations and Electronic Circular Dichroism (ECD) calculation. Cylindromicin (1) exhibited significant tyrosinase inhibition activity. This study highlights Polar fungi as a potential resource for new bioactive natural products.

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