Graphic analysis of the skeletal diversity and complexity of natural products

Author(s):  
Francesco Pietra
Science ◽  
2020 ◽  
Vol 369 (6505) ◽  
pp. 799-806 ◽  
Author(s):  
Xiao Zhang ◽  
Emma King-Smith ◽  
Liao-Bin Dong ◽  
Li-Cheng Yang ◽  
Jeffrey D. Rudolf ◽  
...  

Polycyclic diterpenes exhibit many important biological activities, but de novo synthetic access to these molecules is highly challenging because of their structural complexity. Semisynthetic access has also been limited by the lack of chemical tools for scaffold modifications. We report a chemoenzymatic platform to access highly oxidized diterpenes by a hybrid oxidative approach that strategically combines chemical and enzymatic oxidation methods. This approach allows for selective oxidations of previously inaccessible sites on the parent carbocycles and enables abiotic skeletal rearrangements to additional underlying architectures. We synthesized a total of nine complex natural products with rich oxygenation patterns and skeletal diversity in 10 steps or less from ent-steviol.


VASA ◽  
2010 ◽  
Vol 39 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Schubert

The subclavian steal effect indicates atherosclerotic disease of the supraaortic vessels but rarely causes cerebrovascular events in itself. Noninvasive imaging providing detailed anatomic as well as hemodynamic information would therefore be desirable. From a group of 25 consecutive patients referred for MR angiography, four with absent or highly attenuated signal in one of the vertebral arteries on 3D multislab time-of-flight MR angiography were selected to undergo 3D time-resolved contrast-enhanced MR angiography. The time-resolved 3D contrast series (source images and MIPs) were evaluated visually and by graphic analysis of time-intensity curves derived from the respective V1 and V3 segments of both vertebral arteries on the source images. In two cases with high-grade proximal left subclavian stenosis, time-resolved 3D ce-MRA was able to visualise retrograde contrast filling of the left VA. There was a marked delay in time-to-peak between the left and right V1 segments in one case and a shallower slope of enhancement in another. In the other two cases, there was complete or collateralised segmental occlusion of the VAs.


Planta Medica ◽  
2009 ◽  
Vol 75 (09) ◽  
Author(s):  
T Klimkait ◽  
F Hamy ◽  
V Vidal ◽  
N Gericke ◽  
JJ Sanglier ◽  
...  
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document