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تسجيل

Higher plants , Ricinus communis

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  121

2026-09-28

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Higher plants

Ricinus communis

The beans of Ricinus communis are the source of castor oil, and consist mainly of the triglyceride of ricinoleic (12-hydroxyoleic) acid. Castor oil is well known for its purgative action, which is so strong that it may lead to colic and dehydration. R. communis also contains the extremely toxic peptide ricin, which is present in the seed husks. Ricin is a lectin that consists of two polypeptide chains of 34 kDa each, connected through a disulfide bond. One of the chains (the A-chain) is toxic because it inhibits protein synthesis. The B-chain is a galactose- or N-acetyl galactosamine binding lectin and is responsible for the binding of ricin to cell-surface receptors. Ricin is insoluble in lipids; therefore, it does not occur in medicinal castor oil. Animal experiments indicate that the liver is the primary target organ in ricin poisoning. Oral ingestion of ricin is very dangerous and may cause erythrocyte agglutination, haemorrhagic gastrointestinal irritation, vomiting, profuse watery or bloody purging, fever, convulsions and death. Death after the consumption of a single castor bean has been reported (Knight 1979), although others have survived ingestion of as many as 10 to 15 beans (Aplin and Eliseo 1997). Acute adrenocortical and renal insufficiency have also been demon strated (Balint 1978). There is currently concern that ricin could be used in terrorist attacks. The extreme toxicity of ricin first came to public attention after the Markov case in 1978 in the UK. Georgi Markov, a Bulgarian journalist in exile, was stabbed in the thigh with an umbrella and within a few hours developed high fever and a high leukocyte count. This was followed by a fall in blood pressure and body temperature, and he died on the third day. At autopsy, a small platinum–iridium sphere with tiny holes was found in the subcutaneous tissue. Although the presence of ricin in the bullet was not confirmed analytically, the symptomatology led to the conclusion that ricin was the poison responsible. Immunoassay methods are available for the analysis of ricin. Godal et al. (1981) devised a radioimmunoassay for ricin that was applied subsequently in a patient who ingested 30 castor beans in a suicide attempt. The threat of a terrorist attack using ricin has led to the develop ment of many new methods to detect ricin including lab-on-a-chip and real-time PCRassays.