Concise Enantioselective Total Synthesis of Cardiotonic Steroids 19-Hydroxysarmentogenin and Trewianin Aglycone
作者:Will Kaplan、Hem Raj Khatri、Pavel Nagorny
DOI:10.1021/jacs.6b04029
日期:2016.6.8
The expedient and scalable approach to cardiotonic steroids carrying oxygenation at the C11- and C19-positions has been developed and applied to the total asymmetric synthesis of steroids 19-hydroxysarmentogenin and trewianin aglycone as well as to the assembly of the panogenin core. This new approach features enantioselective organocatalytic oxidation of an aldehyde, diastereoselective Cu(OTf)2-catalyzed
The methanolic extract of the seeds of Corchorus olitorius L. (Moroheiya) was found to show inhibitory effect against Na+-K+-ATPase and positive inotropic activity in the guinea pig isolated atria. Through bioassay-guided separation from the methanolic extract, new cardenolide oligoglycosides called corchorusosides A, B, C, D, and E were isolated together with six known cardenolide oligoglycosides. The structures of new corchorusosides were determined on the basis of chemical and physicochemical evidence. All cardenolide oligoglycosides from the seeds showed potent inhibitory activity against Na+,K+-ATPase, which was equivalent to those of digitoxin and ouabain. The methanolic extract, glycoside fraction, and principal glycoside showed potent acute toxicity by intraperitoneal administration, whereas they showed little acute toxicity by oral administration. Furthermore, by means of HPLC quantitative analysis of the cardiotonic oligoglycosides, it was found that the glycosides mainly distributed in the seeds, while the edible parts such as fresh young leaves and stems contained only trace amount.
Modular Total Synthesis and Cell-Based Anticancer Activity Evaluation of Ouabagenin and Other Cardiotonic Steroids with Varying Degrees of Oxygenation
diastereoselective Michael/aldol cascade approach is used to accomplish concise total syntheses of cardiotonic steroids with varying degrees of oxygenation including cardenolides ouabagenin, sarmentologenin, 19-hydroxysarmentogenin, and 5- epi-panogenin. These syntheses enabled the subsequent structure activity relationship (SAR) studies on 37 synthetic and natural steroids to elucidate the effect of oxygenation
Cardenolides comprise an important family of natural steroids with a wide spectrum of biological activities. Although 19-hydroxysarmentogenin-3-O-α-l-rhamnoside (1a) and trewianin (1b) were structurally determined to have cardenolide structures, their biological activities have not been evaluated. The 6/6/6/5-membered ABCD-ring systems of both 1a and 1b are decorated by a β-oriented C17-butenolide