Cardenolide is a type of steroid

Steroid

A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...

. Many plants contain derivatives, collectively known as cardenolides, including many in the form of cardenolide glycoside

Glycoside

In chemistry, a glycoside is a molecule in which a sugar is bound to a non-carbohydrate moiety, usually a small organic molecule. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme...

s (cardenolides that contain structural groups derived from sugars). Cardenolide glycosides are often toxic; specifically, they are heart-arresting

Cardiac arrest

Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...

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Etymology

Supposedly, the term derives from Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 καρδία kardiā, "heart" and the suffix -enolide. It should not be confused with cardanolide

Cardanolide

Cardanolide is a steroid with a molecular weight of 344.531....

s. Cardanolides are a class of steroids (or aglycones if viewed as cardiac glycoside constituents), and cardenolides are a subtype of this class (see MeSH D codes list).

Structure

Cardenolides are C(23)-steroids with methyl groups at C-10 and C-13 and a five-membered lactone (specifically a butenolide

Butenolide

Butenolides are a class of lactones with a four-carbon heterocyclic ring structure. They are sometimes considered oxidized derivatives of furan. The simplest butenolide is 2-furanone, which is a common component of larger natural products and is sometimes referred to as simply "butenolide". A...

) at C-17. They are aglycone constituents of cardiac glycosides and must have at least one double bond in the molecule. The class includes cardadienolides and cardatrienolides. Members include:

• digitoxin
  Digitoxin
  Digitoxin is a cardiac glycoside. It has similar structure and effects to digoxin . Unlike digoxin , it is eliminated via the liver, so could be used in patients with poor or erratic kidney function. However, it is now rarely used in current Western medical practice...
  
  
• acetyldigitoxin
  Acetyldigitoxin
  Acetyldigitoxin is a cardiac glycoside. It is an acetyl derivative of digitoxin....
  
  s
• digitoxigenin
  Digitoxigenin
  Digitoxigenin is cardenolide, obtained especially by hydrolysis of digitoxin , which is the aglycon of digitoxin....
  
  
• digoxin
  Digoxin
  Digoxin INN , also known as digitalis, is a purified cardiac glycoside and extracted from the foxglove plant, Digitalis lanata. Its corresponding aglycone is digoxigenin, and its acetyl derivative is acetyldigoxin...
  
  
• acetyldigoxin
  Acetyldigoxin
  Acetyldigoxin is a cardiac glycoside. It is an acetyl derivative of digoxin. Its positive cardioinotropic effect starts after 3-4h and maximizes after 6-8h. It is prescribed for congestive chronic cardiac failure class II, III and IV from different reasons, tachysystolic form of fibrillation and...
  
  s
• digoxigenin
  Digoxigenin
  Digoxigenin is a steroid found exclusively in the flowers and leaves of the plants Digitalis purpurea, Digitalis orientalis and Digitalis lanata , where it is attached to sugars, to form the glycosides Digoxigenin (DIG) is a steroid found exclusively in the flowers and leaves of the plants...
  
  
• medigoxin
  Medigoxin
  Medigoxin is a cardiac glycoside closely related to digoxin....
  
  
• strophanthins
• cymarine
• ouabain
  Ouabain
  Ouabain which is also named g-strophanthin, is a poisonous cardiac glycoside.-Sources:Ouabain is found in the ripe seeds of African plants Strophanthus gratus and the bark of Acokanthera ouabaio.-Function:...
  
  
• strophanthidin
  Strophanthidin
  k-Strophanthidin is a cardenolide found in species of the genus Strophanthus. It is the aglycone of k-strophanthin, an analogue of ouabain. k-strophanthin is found in the ripe seeds of Strophanthus kombé....
  
  

Similar in structure in function is Marinobufagenin

Marinobufagenin

Marinobufagin is a cardiotonic bufadienolide steroid secreted by the toad Bufo rubescens and other related species such as Bufo marinus. It is a vasoconstrictor with effects similar to digitalis....

As defense mechanism

Some plant and animal species use cardenolides as a defense mechanism, most notably the monarch butterflies. Adult monarch butterflies store the cardenolides they have built-up as larvae feeding mostly on milkweeds (Asclepias). The cardenolide content in butterflies deters vertebrate predators, with some exceptions of cardenolide-tolerant predators like Black-backed Oriole

Black-backed Oriole

The Black-backed Oriole is a species of bird in the Icteridae family. It is endemic to Mexico.Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montanes.-References:...

s (Icterus abeillei Lesson) and Black-headed Grosbeak

Black-headed Grosbeak

The Black-headed Grosbeak, Pheucticus melanocephalus, is a medium-size seed-eating bird in the same family as the Northern Cardinal, the Cardinalidae. It is sometimes considered conspecific with the Rose-breasted Grosbeak, P...

s (Pheucticus melanocephalus Swainson) that account for 60% of monarch butterfly mortalities in the overwintering sites in central Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

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