Ellagic acid is a

polyphenol Polyphenols () are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as ...

found in numerous fruits and vegetables. It is the dilactone of hexahydroxydiphenic acid.

Name

The name comes from the French term ''acide ellagique'', from the word ''galle'' spelled backward because it can be obtained from ''noix de galle'' (

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or war ...

s), and to distinguish it from ''acide gallique'' ( gallic acid). The molecular structure resembles to that of two gallic acid molecules being assembled "head to tail" and bound together by a C–C bond (as in biphenyl, or in diphenic acid) and two lactone links (cyclic carboxylic esters).

Metabolism

Biosynthesis

Plants produce ellagic acid from hydrolysis of tannins such as

ellagitannin image:Castalagin.svg, 130px, Castalagin is a representative ellagitannin, characterized by coupled gallic acid substituents The ellagitannins are a diverse class of hydrolyzable tannins, a type of polyphenol formed primarily from the oxidative link ...

and geraniin.

Biodegradation

Urolithins are

gut flora Gut microbiota, gut microbiome, or gut flora are the microorganisms, including bacteria, archaea, fungi, and viruses, that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the g ...

human metabolites of dietary ellagic acid derivatives. Ellagic acid has low bioavailability, with 90% remaining unabsorbed from the intestines until metabolized by microflora to the more bioavailable urolithins.

History

Ellagic acid was first discovered by chemist Henri Braconnot in 1831. Maximilian Nierenstein prepared this substance from algarobilla, dividivi, oak bark,

pomegranate The pomegranate (''Punica granatum'') is a fruit-bearing deciduous shrub in the family Lythraceae, subfamily Punica, Punicoideae, that grows between tall. Rich in symbolic and mythological associations in many cultures, it is thought to have o ...

, myrabolams, and valonea in 1905. He also suggested its formation from galloyl-glycine by ''

Penicillium ''Penicillium'' () is a genus of Ascomycota, ascomycetous fungus, fungi that is part of the mycobiome of many species and is of major importance in the natural environment, in food spoilage, and in food and drug production. Some members of th ...

'' in 1915. Julius Löwe was the first person to synthesize ellagic acid by heating gallic acid with

arsenic acid Arsenic acid or arsoric acid is the chemical compound with the chemical formula, formula . More descriptively written as , this colorless acid is the arsenic analogue of phosphoric acid. Arsenate and phosphate salts behave very similarly. Arsenic ...

or silver oxide.

Natural occurrences

Ellagic acid is found in edible nuts. It is also found in oak species such as the North American white oak (''

Quercus alba ''Quercus alba'', the white oak, is one of the preeminent hardwoods of eastern and central North America. It is a long-lived oak, native to eastern and central North America and found from Minnesota, Ontario, Quebec, and southern Maine south as ...

'') and European red oak ('' Quercus robur''). The macrophyte ''

Myriophyllum spicatum ''Myriophyllum spicatum'' (Eurasian watermilfoil or spiked water-milfoil) is a submerged perennial aquatic plant which grows in still or slow-moving water. Eurasian watermilfoil is native to Europe, Asia, and North Africa, but has a wide geograph ...

'' produces ellagic acid. Ellagic acid can be found in the medicinal mushroom '' Phellinus linteus''.

In food

The highest levels of ellagic acid are found in raw chestnuts,

walnut A walnut is the edible seed of any tree of the genus '' Juglans'' (family Juglandaceae), particularly the Persian or English walnut, '' Juglans regia''. They are accessory fruit because the outer covering of the fruit is technically an i ...

s, pecans, cranberries, raspberries, strawberries, and grapes, as well as

distilled beverage Liquor ( , sometimes hard liquor), spirits, distilled spirits, or spiritous liquor are alcoholic drinks produced by the distillation of grains, fruits, vegetables, or sugar that have already gone through alcoholic fermentation. While the ...

s. It is also found in

peach The peach (''Prunus persica'') is a deciduous tree first domesticated and Agriculture, cultivated in China. It bears edible juicy fruits with various characteristics, most called peaches and the glossy-skinned, non-fuzzy varieties called necta ...

es and pomegranates.

Research and health claims

Ellagic acid has been marketed as a

dietary supplement A dietary supplement is a manufactured product intended to supplement a person's diet by taking a pill (pharmacy), pill, capsule (pharmacy), capsule, tablet (pharmacy), tablet, powder, or liquid. A supplement can provide nutrients eithe ...

with various claimed benefits against cancer, heart disease, and other diseases. In the 21st century, numerous U.S.-based supplement companies received

FDA warning letter An FDA warning letter is an official message from the United States Food and Drug Administration (FDA) to a manufacturer or other organization that has violated some rule in a federally regulated activity. The FDA defines an FDA warning letter as: ...

s for promoting ellagic acid with false anti-disease claims that violate the

Federal Food, Drug, and Cosmetic Act The United States Federal Food, Drug, and Cosmetic Act (abbreviated as FFDCA, FDCA, or FD&C) is a set of laws passed by the United States Congress in 1938 giving authority to the U.S. Food and Drug Administration (FDA) to oversee the food safety ...

. Ellagic acid has been identified by the FDA as a "fake cancer 'cure'". There is no

scientific evidence Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems. "Discussions about empirical ev ...

to support the claims that ellagic acid can treat or prevent cancer.

References

{{Unproven and disproven cancer treatments Antioxidants Alternative cancer treatments Biphenyls Coumarins Ellagitannins Health fraud Isocoumarins Lactones Pomegranate ellagitannins Pyrogallols Catechols Heterocyclic compounds with 4 rings Oxygen heterocycles