Plant Cardenolides: Multifunctional Medicinal Agents

Cardenolides are a class of compounds steroidal in nature, belonging to the cardiac glycoside group of secondary metabolites. They consist of a sugar part and a non-sugar part consisting of a steroidal cyclopentanoperhydrophenanthrene ring with lactone substitution at the β-17 position. Cardenolides are found in angiosperm plant families like Plantiginaceae, Asclepiadaceae, Apocynaceae, Brassicaceae, Cruciferae, Liliaceae, Moraceae, Ranunculaceae, and Scrophulariaceae. These include some important glycosides, such as digitoxin, digoxin, Ouabain, Calotropin, etc. with profound pharmacological potential. Moreover, cardenolides have toxic effects for which these have been used in poison arrows and for self-harm purposes. Traditionally, these were used to treat congestive heart failure. However, recently they have emerged as promising agents to exhibit anticancer, antiviral, anti-inflammatory, neuroprotective, and various other therapeutic roles. Cardenolides like Digoxin and Digitoxin have been used in the treatment of heart failure and atrial fibrillation. Toxicarioside A, and Calotropin have been reported to suppress tumor growth and are used as anticancer agents, Strophalloside and Oubain are reported to be involved in apoptosis. Oleandrin is an antiproliferative agent and can inhibit IL-8 which is responsible for cystic fibrosis.