Emodin
Emodin is an organic compound. Classified as an anthraquinone, it can be isolated from rhubarb, buckthorn, and Japanese knotweed. Emodin is particularly abundant in the roots of the Chinese rhubarb, knotweed and knotgrass as well as Hawaii 'au'auko'i cassia seeds or coffee weed. It is specifically isolated from Rheum palmatum L. It is also produced by many species of fungi, including members of the genera Aspergillus, Pyrenochaeta, and Pestalotiopsis, inter alia. The common name is derived from Rheum emodi, a taxonomic synonym of Rheum australe, and synonyms include emodol, frangula emodin, rheum emodin, 3-methyl-1,6,8-trihydroxyanthraquinone, Schüttgelb, and Persian Berry Lake.
Pharmacology
Emodin is an active component of several plants used in traditional Chinese medicine such as Rheum palmatum, 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 coronaviruses such as SARS-CoV-2, 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 australisCassia occidentalisCassia siamea- Frangula alnusGlossostemon bruguieriKalimeris indicaPolygonum hypoleucumReynoutria japonica Rhamnus alnifolia, the alderleaf buckthornRhamnus cathartica, the common buckthornRheum palmatumRumex nepalensisSenna obtusifolia Thielavia subthermophilaVentilago madraspatana