Emodin is a purgative resin

Resin

Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...

, 6-methyl-1,3,8-trihydroxyanthraquinone, from rhubarb

Rhubarb

Rhubarb is a group of plants that belong to the genus Rheum in the family Polygonaceae. They are herbaceous perennial plants growing from short, thick rhizomes. They have large leaves that are somewhat triangular-shaped with long fleshy petioles...

, the buckthorn

Buckthorn

The Buckthorns are a genus of about 100 species of shrubs or small trees from 1-10 m tall , in the buckthorn family Rhamnaceae...

 and Japanese Knotweed

Japanese knotweed

Japanese Knotweed is a large, herbaceous perennial plant, native to eastern Asia in Japan, China and Korea...

 (Fallopia japonica syn. Polygonum cuspidatum). The term may also refer to any one of a series of principles isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

ic with the emodin of rhubarb.

Pharmacology

Emodin is being studied as a potential agent that could reduce the impact of type 2 diabetes. It is a potent selective inhibitor

Enzyme inhibitor

An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...

 of the enzyme 11β-HSD1. In studies in obese mice, emodin limits the effect of glucocorticoid

Glucocorticoid

Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...

s and may therefore ameliorate diabetes and insulin resistance.

Pharmacological studies have demonstrated that emodin when isolated from rhubarb exhibits anti-cancer effects on several human cancers including human pancreatic cancer. Emodin in rhubarb extracts may also have neuroprotective properties against glutamate toxicity,
but in other studies it seems to increase inflammation and have other possible neurotoxic effects.

Aloe-emodin (1,3,8-trihydroxyanthraquinone) is a variety of emodin found in Socotrine, Barbados, and Zanzibar aloes, but not in Natal aloes.

List of plants that contain the chemical

• Cassia obtusifolia
• Fallopia japonica, syn. Polygonum cuspidatum
• Senna obtusifolia
  Senna obtusifolia
  Senna obtusifolia is a legume in the genus Senna, sometimes separated in the monotypic genus Diallobus. It grows wild in North, Central, and South America, Asia, Africa, and Oceania, and is considered a particularly serious weed in many places...
  
  
• Ventilago madraspatana
• Kalimeris indica
  Kalimeris indica
  Kalimeris indica, also known as Indian aster, belonging to the Asteraceae family, is an edible plant found in Asia and Hawaii. It is used in several Asian cuisines....
  
  
• Rumex nepalensis
• Polygonum hypoleucum
• Cassia occidentalis
• Cassia siamea
• Acalypha australis
  Acalypha
  Acalypha is a plant genus of the family Euphorbiaceae. It is the sole genus of the subtribe Acalyphinae. With 450 to 500 species of herbs and shrubs, the genus is only behind Euphorbia, Croton and Phyllanthus in term of Malpighiales diversity...
  
  
• Rheum palmatum