Cardiac glycosides plants

Some insects can protect themselves against the toxins present in their food plants by storing them. One example is the monarch butterfly, the caterpillars of which store potentially toxic cardiac glycosides obtained from a food plant, the milkweed (see Harborne 1993). Subsequently, the stored glycosides have a deterrent effect upon blue jays that feed upon them. 

Cholesterol is probably the best known steroid because of its association with atherosclerosis. However, biochemically it is also of significance because it is the precursor of a large number of equally important steroids that include the bile acids, adrenocortical hormones, sex hormones, D vitamins, cardiac glycosides, sitosterols of the plant kingdom, and some alkaloids. 

Steroids, compounds with a cyclopenta[a]phenanthrene skeleton (15), include a wide range of natural products such as sterols (e.g., cholesterol), sex hormones, adrenocorticoid hormones, cardiac glycosides and vitamin D [31]. Sterols are steroids having a hydroxyl group at position 3 of the basic skeleton. Steroids can be found both in plants and in animals. 

This process starts with the synthesis of novel chemical compounds. Substances with complex structures may be obtained from various sources, e.g., plants (cardiac glycosides), animal tissues (heparin), microbial cultures (penicillin G), or human cells (urokinase), or by means of gene technology (human insu-Un). As more insight is gained into structure-activity relationships, the search for new agents becomes more clearly focused. 

Cardiac glycosides are drags used in the treatment of congestive heart failure or cardiac arrhythmia, by inhibiting the Na+/K+ pump. This inhibition increases the amount of Ca + ions available for contraction and improves cardiac output and reduces distention of the heart. Cardiac glycosides are extracted from plant material. 

Cardiac glycosides have high biological activity not only medically but also as defense substances in both plants and insects (8,9). A separation of two cardiac glycosides is shown in Figure 11. To reduce the peak tailing the ion source temperature and the solvent flow rate were increased. 

The bulk of plant-derived medicines can be categorized into a number of chemical families, including alkaloids, flavonoids, terpenes and terpenoids, steroids (e.g. cardiac glycosides), as well as coumarins, quinines, salicylates and xanthines. A list of some better-known plant-derived drugs is presented in Table 1.16. 

Types of Cardiac Glycoside. Three groups of plants produce cardenolides the Digitalis species, growing in temperate climates the Strophanthus species, of tropical provenance and Scilla (sea onion or squill), a Mediterranean plant. 

The cardiac glycosides are mainly obtained from plants e.g. digitalis, stropanthus and squill species and also present in certain other plants and animals. In 1776, William Withering, a Birmingham... 

Many triterpenes also have anti herbivore activity. In general, those which are highly oxygenated seem to be more active in this regard M). The role of cardiac glycosides, insects and their predators has been reviewed (91-94). A number of metabolically altered triterpenes from the Rutaceae, Meliaceae and Simaroubaceae are antifeedants. Extracts of neem tree seeds (Azadirachta indica. Meliaceae) were shown to be repellent to a number of insects when applied to various crop plants at low concentrations. The probable active compound is tetranortriter-pene, azadirachtin (9 ). This compound from the leaves and fruits... 

Cardiac glycosides with bufadienohde skeleton, e.g. proscillaridin A, have been found in plants (e.g. squill, Drimia maritima). 

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