The Digitalis Series

The digitalis series embraces a considerable number of substances that are characterized by their action on the heart. They are widely distributed in the vegetable kingdom in very different botanical families and have long been used for various purposes in civilized countries. Some of them were employed as remedies by the laity long before their virtues were recognized by the medical profession, and others have been used as arrow poisons and ordeal poisons by the natives of different parts of Africa and the Eastern Archipelago. 

The distribution of cardiac glycosides in the plant varies in different species. Digitalis is obtained from the leaves and seeds strophanthus, from the seeds squill, from the bulbs Convallaria, from the flowers and ouabaio, from the wood and bark. In addition, there are saponin bodies that do not show the typical digitalis effect on the heart but which are extracted along with the glycosides, which possess the cardiac actions. 

Digitalis purpurea L. from Kohler s Medicinal Plants 

FIGURE 35.2 Foxglove (Digitalis purpurea) in bloom. Note the thimble (finger)-shaped flowers from which it derives its name and the leaves from which medicinal digitalis is derived. 

FIGURE 35.3 Structural formulas of the aglycones of the cardiac glycosides. 

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The close relationship of the various glycosides of the digitalis series to each other is especially well depicted when the aglycones into which they are hydrolyzed are arranged in a series, as follows ... 

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