Plants Affecting the Cardiovascular System ( 17-Sep-2002)

A large group of unrelated plants have toxic compounds that have a direct effect on the heart and blood vessels and can cause the death of animals that consume them. The most recognized of these compounds are the cardiac glycosides, of which digoxin, found in foxglove (Digitalis spp.), is best known. The toxic and pharmacologic properties of digoxin have been known for a long time. Because of its effects on the heart at therapeutic levels, it is routinely used to treat congestive heart failure in humans and animals [1]. Other cardiotoxic compounds found in plants such as yew (Taxus spp.), rhododendrons (Rhododendron spp.), laurels (Kalmia spp.), and the avocado (Persea spp.) are responsible for poisoning in animals and humans. Cardiac Glycosides Cardiac glycosides are found in 11 plant families including the Apocynaceae, Asclepiadaceae, Celastraceae, Brassicaceae, Lilaceae, Moraceae, Fabaceae, Ranunculaceae, Scrophulariaceae, Sterculiaceae, and Tiliaceae [2]. The glycosides that have specific effects on the heart are present in at least 34 genera of these plant families [2,3]. There are 2 basic groups of glycosides in plants, cardenolides and bufadienolides, both of which have direct effects upon cardiac function. The best known cardiac glycosides (cardenolides) are digoxin and digitoxin, derived from the parent glycoside digitalis. The therapeutic value of digitalis in treating heart failure was first recognized in 1775 [4] and it is now produced commercially for therapeutic purposes from foxglove (Digitalis lannata) [5]. Immunologic methods have enabled detection of glycosid