Cardenolide modified

D. C. Rohrer, D. S. Fullerton, K. Yoshioka, A. H. L. Frome, K. Ahmed (1979). Functional receptor mapping for modified cardenolides use of the Prophet system. In E. C. Olson, R. E. Christoffersen (Eds.). Computer Assisted Drug Design. Washington, DC American Chemical Society, pp. 259-279. 

Because a substantial excess of the halide is used in the Koenigs-Knorr synthesis of cardenolides, it is usually difficult, if not impossible, to secure the acylated intermediate in crystalline form. Hence, Reichstein nd coworkers18 introduced a procedure whereby the whole of the products arising from the coupling reaction are saponified, employing a solution of potassium hydrogen carbonate in aqueous methanol. This modified transesterification procedure renders all extraneous carbohydrate materials water-soluble the methanol is removed by evaporation, leaving an aqueous solution from which the (deacylated) cardenolide may be obtained by... 

BR biosynthesis inhibitors are potentially valuable tools for studying BR biosynthesis (Asami and Yoshida, 1999). Triazoles are known BR biosynthesis inhibitors however, they are not very specific and also suppress the synthesis of gibberellic acid (Rademacher, 2000) or cardenolides (see above). A more specific BR biosynthesis inhibitor, brassinazole, was synthesized by modifying uniconazole (Min et al., 1999). Treatment of Arabidopsis seedlings with brassinazole resulted in a phenotype typical of BR-deficient mutants (Asami... 

Luta, M., Hensel, A. and Kreis, W. (1997) p-D-Fucosidase and other cardenolide glycoside-modifying enzyme in Digitalis lanata EHRH, in 45th Annual Congress on Medicinal Plant Research, Regensburg. 

The y-lactone ring in cardenolides has also been modified.Digitoxigenin (520) or isodigitoxigenin (521) were directly transformed into a mixture of isomeric lactams (523) by treatment with ammonia or methylamine. The lactol-amide intermediate (522) could be isolated when the reaction was performed at room temperature, and this was transformed to the lactam (523) by dilute acid. Gitoxigenin (524) reacted in an analogous way to afford the related lactams (525). From these experiments, it appears that the reaction with cardenolides gives... 

Functional Receptor Mapping for Modified Cardenolides Use of the PROPHET System... 

Smith, P., Brown, L., Boutagy, J., and Thomas. R., Cardenolide analogues. Part 14. Synthesis and biological activity of glucosides of C17P-modified derivatives of digitoxigenin, J. Med. Chem., 25, 1222, 1982. 

Because the butterfly carries warning coloration (aposematic labeling) that the bird learns to recognize quickly, only a fraction, about 50% of the insects, need to have the toxic compounds within their bodies for all of the insects to be protected (Brower, 1969). Both the plants and the insects differ in cardenolide content. Monarch butterflies do not accumulate each of the compounds in the plant equally well. Some cardenolides are absorbed intact, others are biochemically modified, and yet others are excreted. 

Over its natural range in North America, the female monarch butterfly may lay her eggs on several Asclepias species that differ in the complement and amount of cardenolides present. By TLC analysis of adult butterflies, it is possible to determine the species upon which the larva feed. Depending on the complement and quantity of cardenolides present in the host plant, the larvae are able to adjust their diet to modify the amount of cardenolide sequestered (Harbome, 1991). 

Medarde and co-workers prepared modified Hajos-Parrish ketones 56 and 57 as simple cardenolide analogs. ... 

A number of glycosides with the sugar(s) attached to C-3 of a steroid have a strongly modified and shortened side chain that is present as a five- or six-membered unsaturated lactone ring. The former are called cardenolides and the latter bufadienolides. About two dozen sugars including D-glucose have been iso-... 

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