Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

. Classified as an

anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic hydrocarbon, aromatic organic compound with formula . Several isomers exist but these terms usually refer to 9,10-anthraquinone (IUPAC: 9,10-dioxoanthracene) wherein th ...

, it can be isolated from rhubarb, buckthorn, and Japanese knotweed ('' Reynoutria japonica'' syn. ''Polygonum cuspidatum''). Emodin is particularly abundant in the roots of the Chinese rhubarb (''

Rheum palmatum ''Rheum palmatum'' is a species of flowering plant in the knotweed family (botany), family Polygonaceae. It is commonly called Chinese rhubarb, ornamental rhubarb, Turkey rhubarb or East Indian rhubarb. ''Rheum palmatum'' is a herbaceous peren ...

''), knotweed and knotgrass ('' Polygonum cuspidatum'' and '' Polygonum multiflorum'') as well as Hawaii ‘au‘auko‘i cassia seeds or coffee weed (''Semen cassia''). It is specifically isolated from ''Rheum palmatum'' L. It is also produced by many species of fungi, including members of the genera ''

Aspergillus ' () is a genus consisting of several hundred mold species found in various climates worldwide. ''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...

'', '' Pyrenochaeta'', and ''

Pestalotiopsis ''Pestalotiopsis'' is a genus of ascomycete fungi in the Sporocadaceae family. Taxonomy The genus was circumscription (taxonomy), circumscribed by René Leopold Alix Ghislain Jules Steyaert in Bull. Jard. Bot. Etat. vol.19 on page 300 in 1949. T ...

'', inter alia. The common name is derived from ''Rheum emodi'', a taxonomic synonym of '' Rheum australe'' (Himalayan rhubarb), and synonyms include emodol, frangula emodin, rheum emodin, 3-methyl-1,6,8-trihydroxyanthraquinone, Schüttgelb (Schuttgelb), and Persian Berry Lake.

Pharmacology

Emodin is an active component of several plants used in

traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medicine, alternative medical practice drawn from traditional medicine in China. A large share of its claims are pseudoscientific, with the majority of treatments having no robust evidence ...

(TCM) such as ''

'', '' Polygonum cuspidatum'', and '' Polygonum multiflorum''. It has various actions including laxative, anticancer, antibacterial and antiinflammatory effects, and has also been identified as having potential antiviral activity against

coronavirus Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the comm ...

es such as

SARS-CoV-2 Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a strain of coronavirus that causes COVID-19, the respiratory illness responsible for the COVID-19 pandemic. The virus previously had the Novel coronavirus, provisional nam ...

, being one of the major active components of the antiviral TCM formulation ''Lianhua Qingwen''. Emodin has been shown to inhibit the ion channel of protein 3a, which could play a role in the release of the virus from infected cells.

List of species

The following plant species are known to produce emodin: * '' Acalypha australis'' * '' Cassia occidentalis'' * '' Cassia siamea'' *'' Frangula alnus'' * '' Glossostemon bruguieri'' * '' Kalimeris indica'' * ''Polygonum hypoleucum'' * '' Reynoutria japonica'' ( syn. ''Fallopia japonica'') (syn. ''Polygonum cuspidatum'') * '' Rhamnus alnifolia'', the alderleaf buckthorn * ''

Rhamnus cathartica ''Rhamnus cathartica'', the European buckthorn, common buckthorn, purging buckthorn, or just buckthorn, is a species of small tree in the flowering plant family Rhamnaceae. It is native to Europe, northwest Africa and western Asia, from the cent ...

'', the common buckthorn * ''

'' * ''Rumex nepalensis'' * '' Senna obtusifolia'' (syn. ''Cassia obtusifolia'') * '' Thielavia subthermophila'' * ''Ventilago madraspatana'' Emodin also occurs in variable amounts in members of the

crustose lichen Crustose lichens are lichens that form a crust which strongly adheres to the Substrate (biology), substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. The basic structure of crustose lichen ...

genus '' Catenarina''.

Compendial status

* British Pharmacopoeia * List of compounds with carbon number 15

References

{{Purinergics Trihydroxyanthraquinones Virucides Resorcinols 3-Hydroxypropenals within hydroxyquinones