Abrin is a highly toxic protein that is derived from the seeds of the plant Abrus precatorius, also known as the rosary pea or jequirity bean. The brightly colored seeds of this plant contain about 0.08% of abrin. The toxin is found within the seeds and its release is prevented by the seed coat. If the seed coat is injured or destroyed (by chewing, for example) the toxin may be released. The toxic effects of abrin were first reported in the late 19th century when it was used as a poison in India.
Abrus precatorius is native to tropical regions of Africa and Asia. It is found in many countries across these regions, including India, Indonesia, Thailand, China, and Nigeria. However, the plant has been introduced to many other parts of the world, including the Caribbean, South America, and the southern United States, where it is now considered an invasive species. Despite its invasive status, the plant is still widely cultivated for its ornamental value and medicinal properties.
Abrin has a median lethal dose of 0.7 micrograms per kilogram of body mass when given to mice intravenously. The median toxic dose for humans ranges from 10 to 1000 micrograms per kilogram when ingested and is 3.3 micrograms per kilogram when inhaled.
Abrin and ricin are two highly toxic proteins derived from plants. Ricin is derived from the seeds of the castor bean plant (Ricinus communis). Both toxins are classified as ribosome-inactivating proteins (RIPs), which means that they are capable of inactivating ribosomes[1], leading to cell death. However, abrin is approximately 75 times more toxic than ricin, with a lethal dose of only a few micrograms per kilogram of body weight, compared to a lethal dose of several milligrams per kilogram of body weight for ricin. Additionally, while both toxins have potential therapeutic uses, particularly as cytotoxic agents for the treatment of cancer, their high toxicity makes them dangerous to handle and limits their clinical applications.
Studies have shown that abrin can inhibit protein synthesis in tumor cells, leading to their death. Additionally, abrin can be conjugated with targeting agents, such as antibodies or peptides, to selectively deliver the toxin to cancer cells while sparing normal cells, reducing toxicity and increasing efficacy. However, the high toxicity of abrin and the difficulty in delivering it to target tissues have limited its clinical applications.
The symptoms of abrin poisoning depend on the route of exposure and the dose received. Inhalation of abrin can cause symptoms such as coughing, difficulty breathing, fever, and chest tightness, which can progress to respiratory failure and death. Ingestion of abrin can cause symptoms such as nausea, vomiting, abdominal pain, diarrhea, and dehydration, which can progress to circulatory shock and multiple organ failure.
Skin exposure to abrin can cause symptoms such as rash, redness, and blistering. The onset of symptoms can occur within hours to days after exposure, and there is no specific antidote for abrin poisoning. Treatment is primarily supportive and includes decontamination, airway management, and symptomatic care.
A 16-year-old boy has pleaded guilty to attempting to buy a deadly biological toxin over the internet. The teenager from Mossley, Greater Manchester – who cannot be named for legal reasons – wanted to obtain a poison called abrin, said to be 30 times more toxic than ricin. He entered a guilty plea at Manchester youth court on Wednesday on the basis that he tried to purchase the toxin online to kill himself, Greater Manchester police said.
The Independent London, Greater London, England
Thursday, February 19, 2015
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However, due to its high toxicity, abrin is classified as a Schedule I substance under the United States Controlled Substances Act, and possession or use of abrin is strictly regulated.
Footnotes
- Ribosomes are cellular structures that play a critical role in protein synthesis, the process by which cells produce proteins. They are composed of two subunits, a large subunit and a small subunit, each of which contains a combination of proteins and RNA molecules known as ribosomal RNA (rRNA). Ribosomes work by reading the genetic code stored in messenger RNA (mRNA) molecules and using this code to assemble chains of amino acids into proteins. During this process, the ribosome moves along the mRNA molecule, matching each three-letter codon with the appropriate amino acid. This continues until a stop codon is reached, at which point the protein is complete and the ribosome disassembles. Ribosomes are present in all living cells and are essential for life. [Back]
Further Reading
Sources
- Balali-Mood, M., & Saber, H. (2012). Recent advances in the clinical toxicology of abrin: a review. Toxicon, 60(5), 721-729. https://doi.org/10.1016/j.toxicon.2012.05.020
- Duke, J. A. (2002). Handbook of medicinal herbs (Vol. 1). CRC press.
- Mukherjee, A. K., & Sengupta, S. (2013). Ribosome-inactivating proteins: an overview. Toxicon, 69, 385-391. https://doi.org/10.1016/j.toxicon.2012.10.018
- Duke, J. A. (2002). Handbook of medicinal herbs (Vol. 1). CRC press.
- Lemmens, R. H. M. J., Bunyapraphatsara, N., & Room, P. M. (Eds.). (1999). Medicinal and poisonous plants 1. PROSEA (Plant Resources of South-East Asia) Foundation.
- USDA, NRCS. (2023). The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA. Retrieved from https://plants.usda.gov/home.htm
- Franz, D. R., Jaax, N. K., & Korch, G. W. (1997). Ricin Toxin. In Medical aspects of chemical and biological warfare (pp. 631-642). Office of The Surgeon General US Army.
- Olsnes, S., & Stirpe, F. (1980). Immunotoxins: A new approach to cancer therapy. The Quarterly Review of Biology, 55(4), 585-610. https://doi.org/10.1086/412988
- “Teenager from Manchester pleads guilty to trying to buy deadly toxin” The Guardian
- “Abrin” Wikipedia
- Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular biology of the cell (4th ed.). Garland Science.
- Ramakrishnan, V. (2002). Ribosome structure and the mechanism of translation. Cell, 108(4), 557-572. https://doi.org/10.1016/s0092-8674(02)00619-0
- Wilson, D. N., & Doudna Cate, J. H. (2012). The structure and function of the eukaryotic ribosome. Cold Spring Harbor Perspectives in Biology, 4(5), a011536. https://doi.org/10.1101/cshperspect.a011536
