On cardioactive steroids. XII. The synthesis of (natural) bufalin and ??-isobufalin

1983 ◽  
Vol 66 (8) ◽  
pp. 2632-2640 ◽  
Author(s):  
Karel Wiesner ◽  
Thomas Y. R. Tsai ◽  
Alina Sen ◽  
Ravindra Kumar ◽  
Masayoshi Tsubuki
Keyword(s):  
Cardioactive Steroids

ChemInform Abstract: ON CARDIOACTIVE STEROIDS. IV. A NEW SYNTHESIS OF CARDENOLIDES

1981 ◽  
Vol 12 (36) ◽  
Author(s):  
R. MARINI-BETTOLO ◽  
P. FLECKER ◽  
T. Y. R. TSAI ◽  
K. WIESNER
Keyword(s):  
New Synthesis ◽  
Cardioactive Steroids

Mercury blocks Na-K-ATPase by a ligand-dependent and reversible mechanism

1992 ◽  
Vol 262 (5) ◽  
pp. F830-F836 ◽  
Author(s):  
B. M. Anner ◽  
M. Moosmayer ◽  
E. Imesch
Keyword(s):  
Metal Binding ◽  
Inhibitory Concentration ◽  
Potent Inhibitor ◽  
Inhibitory Receptor ◽  
Protein Inhibitor ◽  
Binding Interface ◽  
Cellular Expression ◽  
Metal Binding Domain ◽  
Cardioactive Steroids ◽  
Atpase Inhibition

An inhibitory receptor for cardioactive steroids such as digoxin and ouabain is located at the extracellular surface of the Na-K-adenosinetriphosphatase (ATPase) molecule. Besides cardioactive steroids, mercury is a potent inhibitor of the Na-K-ATPase activity. The half-maximal inhibitory concentration (IC50), determined within 30 min at 37 degrees C at 1 microgram protein/ml, was 200 nM, despite the presence of 1 mM EDTA; the IC50 decreased with increasing protein/inhibitor ratio, and it reached 2.7 microM at 0.1 mg protein/ml and 20 microM at 1 mg protein/ml. The IC50 for Na-K-ATPase inhibition by the diuretic compound mersalyl was 4 and 5 microM for the nondiuretic p-chloromercuribenzenesulfonic acid at 0.1 mg protein/ml. The IC50 for HgCl2 inhibition was modulated by the presence of EDTA as well as by the pump ligands Mg, Na, K, and ATP. The E2 conformation of the Na-K-ATPase molecule was more sensitive to HgCl2 than the E1 conformation. The mercury antidote 2,3-dimercapto-1-propanesulfonic acid was able to reactivate approximately 70% of the blocked enzyme. In conclusion, a metal-binding domain of the Na-K-ATPase molecule with particular high affinity for Hg(II) was described functionally in the present work. Therefore Na-K-ATPase belongs to the metal-binding proteins. Metals may modulate the cellular expression and activity of the system by interacting with its metal-binding interface.

On cardioactive steroids. IV. A new synthesis of cardenolides

1981 ◽  
Vol 59 (9) ◽  
pp. 1403-1404 ◽  
Author(s):  
Rinaldo Marini-Bettolo ◽  
Petr Flecker ◽  
Thomas Y. R. Tsai ◽  
Karel Wiesner
Keyword(s):  
Efficient Synthesis ◽  
New Synthesis ◽  
Cardioactive Steroids

A new and efficient synthesis of Digitalis cardenolides via methoxyfuryl intermediates is described.

A stereoselective synthesis of digitoxin. On cardioactive steroids. XIII

1984 ◽  
Vol 62 (7) ◽  
pp. 1403-1405 ◽  
Author(s):  
Thomas Y. R. Tsai ◽  
Haolun Jin ◽  
Karel Wiesner
Keyword(s):  
Stereoselective Synthesis ◽  
New Method ◽  
Cardioactive Steroids ◽  
Acid Catalyzed

The first highly stereoselective synthesis of digitoxin is described. The furyl derivative of digitoxigenin was coupled with one unit of digitoxose using our previously described acid catalyzed method. For the second and third glycosylation a new method involving ethyl thioglycosides and 1,3-participation by a p-methoxy benzoate group was developed. As the final step after deprotection of the triglycoside, the 17-furyl group in the steroid aglycone was converted to a butenolide by our oxidative method.

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