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Record Information
Creation Date2009-07-03 22:06:25 UTC
Update Date2014-12-24 20:25:34 UTC
Accession NumberT3D2481
Common NameRicin
DescriptionRicin is a plant toxin found in the castor bean (Ricinus communis). It can cause severe allergic reactions, and exposure to small quantities can be fatal. (5)
Compound Type
  • Amide
  • Amine
  • Natural Compound
  • Organic Compound
  • Plant Toxin
  • Protein
Protein StructureT3d2481
Ricin A chain
Ricin B chain
rRNA N-glycosidase
Chemical FormulaNot Available
Average Molecular Mass64089.975 g/mol
CAS Registry Number9009-86-3
SequenceNot Available
Chemical Taxonomy
DescriptionNot Available
KingdomOrganic Compounds
Super ClassOrganic Acids
ClassCarboxylic Acids and Derivatives
Sub ClassAmino Acids, Peptides, and Analogues
Direct ParentPeptides
Alternative ParentsNot Available
SubstituentsNot Available
Molecular FrameworkNot Available
External DescriptorsNot Available
Biological Properties
StatusDetected and Not Quantified
Cellular LocationsNot Available
Biofluid LocationsNot Available
Tissue LocationsNot Available
PathwaysNot Available
ApplicationsNot Available
Biological RolesNot Available
Chemical RolesNot Available
Physical Properties
AppearanceEither a white powder or a liquid in crystalline form. (5)
Experimental Properties
Melting PointNot Available
Boiling PointNot Available
Solubility>10 mg/mL
LogPNot Available
Predicted PropertiesNot Available
Spectrum TypeDescriptionSplash Key
Toxicity Profile
Route of ExposureIngestion, injection or inhalation. (5)
Mechanism of ToxicityPure ricin consists of a neutral A chain and an acidic B chain connected by S--S bonds. The A chain is capable of inhibiting protein synthesis which results in its toxic action. The B chain functions as carrier moiety which binds the toxin to the cell surface. Ricin intoxication is proposed to have three main phases: Intravasal RBC aggregation, acute adrenocortical insufficiency and disturbances of carbohydrate metabolism dur to liver damage. Ricin works by penetrating the cells of the body and inhibiting cell protein synthesis. By attaching to a carbohydrate chain on the cell surface, the ricin molecule anchors itself to the cell, is subsequently engulfed and enters the inner parts of the cell where it reacts with the 60S ribosomal subunit and interferes with the normal protein synthesis process of the cell. Without these proteins, cells cannot survive. The severity of the effects of ricin poisoning vary on the means of exposure to the substance. (5, 1)
MetabolismThe mechanism of metabolism of ricin has not been investigated but presumably consists of proteolysis (6). Free toxin may be removed by opsonization via the reticuloendothelial system (primarily the liver and kidneys) or it may be degraded through cellular internalization via the lysosomes. Lysosomes are membrane-enclosed organelles that contain an array of digestive enzymes, including several proteases.
Toxicity ValuesLD50: 2.8-8 ug/kg (Intraperitoneal, Mouse) (6) LD50: 2.8-8 ug/kg (Intravenous, Mouse) (6)
Lethal Dose500 ug for an adult human. (5)
Carcinogenicity (IARC Classification)No indication of carcinogenicity to humans (not listed by IARC).
Uses/SourcesRicin is a plant toxin found in the castor bean (Ricinus communis). Some researchers have speculated about using ricins in the treatment of cancer, as a so-called "magic bullet" to destroy targeted cells. Ricin could be linked to a monoclonal antibody to target malignant cells recognized by the antibody. The United States investigated ricin for its military potential during the First World War. (5)
Minimum Risk LevelNot Available
Health EffectsLong term organ damage is likely in survivors. Ricin causes severe diarrhea and victims can die of shock. Ingestion results in severe gastroenteritis, often hemorrhagic. Later, victims may become drowsy, confused, irrational, and comatose; convulsions occur. Moreover, peripheral vascular collapse and renal failure may develop. Local inflammatory lesions result from dust in the eyes, nose and throat. (5, 2)
SymptomsRicin irritates the skin and eyes. Inhalation may cause respiratory distress, fever, cough, nausea, tightness in the chest, heavy sweating and pulmonary edema. Ingestion can result in vomiting, diarrhea, severe dehydration, low blood pressure, hallucinations, and seizures. In either case, death may result from respiratory failure or liver, speen, and/or kidney damage. (7, 5)
TreatmentAs there is no antidote for ricin, treatment consists of supportive medical care to minimize the effects of the poisoning. This may include respiratory assistance, intravenous fluids, medications to treat conditions such as seizure and low blood pressure, or administering activated charcoal. (7, 5)
Normal Concentrations
Not Available
Abnormal Concentrations
Not Available
DrugBank IDNot Available
HMDB IDNot Available
PubChem Compound IDNot Available
ChEMBL IDNot Available
ChemSpider IDNot Available
KEGG IDNot Available
UniProt IDP02879
ChEBI IDNot Available
BioCyc IDNot Available
CTD IDNot Available
Stitch IDRicin
ACToR IDNot Available
Wikipedia LinkNot Available
Synthesis ReferenceNot Available
General References
  1. Uchida E, Kagawa N, Sakaki T, Urushino N, Sawada N, Kamakura M, Ohta M, Kato S, Inouye K: Purification and characterization of mouse CYP27B1 overproduced by an Escherichia coli system coexpressing molecular chaperonins GroEL/ES. Biochem Biophys Res Commun. 2004 Oct 15;323(2):505-11. [15369780 ]
  2. Lehmann B, Tiebel O, Meurer M: Expression of vitamin D3 25-hydroxylase (CYP27) mRNA after induction by vitamin D3 or UVB radiation in keratinocytes of human skin equivalents--a preliminary study. Arch Dermatol Res. 1999 Sep;291(9):507-10. [10541881 ]
  3. Gosselin RE, Hodge HC, Smith RP, and Gleason MN (1976). Clinical Toxicology of Commercial Products. 4th ed. Baltimore: Williams and Wilkins.
  4. The Merck Index (1976). The Merck Index. 9th ed. Rahway, New Jersey: Merck & Co., Inc.
  5. Wikipedia. Ricin. Last Updated 5 August 2009. [Link]
  6. National Institutes of Health, Division of Occupational Health and Safety (1988). Safety Data Sheet for Ricin. [Link]
  7. Wikipedia. Abrin. Last Updated 24 April 2009. [Link]
Gene Regulation
Up-Regulated GenesNot Available
Down-Regulated GenesNot Available


1. RNA
  1. Wikipedia. Ricin. Last Updated 5 August 2009. [Link]