Ricin plant sources

Abrin is a plant source Type 2 RIP. It is found in Abrus precatorius (rosary pea, Indian licorice, jequirity bean). The toxicology of abrin is considered to be very similar to ricin. A similar Abrus toxin is pulchellin, produced by A. pul-chellus (Millard and LeClaire, 2008). The rosary pea has been reported to be more toxic than castor beans (Griffiths et al, 1994). Species sensitivity is variable and horses are considered to be the most sensitive. The mature goat is considered to be a more resistant species and 2 g of seed/kg body weight is reported as a lethal dose. The lethal dose for cattle is reported at 600 mg of seed/kg body weight. It is likely that abrin is denatured in the rumen (Burrows and Tyrl, 2001). 

Toxins are any poisonous substances that can be produced by an animal, plant, or microbe. Because of their complexity, most toxins are difficult to synthesize in large quantities by traditional chemical means. However, they may be harvested from cultured sources or produced by genetically engineered microbes. Toxins are odorless, tasteless, and nonvolatile. Ricin (C16-A036) and saxitoxin (C16-A018) are the only toxins listed in the Chemical Weapons Convention (Schedule 1). 

Chemicals come in all shapes and sizes and derive from a variety of sources. While to many people the words chemical and indeed poison are synonymous with man-made things such as dioxin, organo-phosphates, pesticides, and nerve gas, there are many, many other chemicals that occur naturally These may be produced by plants, for example belladonna in deadly nightshade, and ricin in the castor bean, or bacteria, for example botulinum toxin. Various animals such as snakes and spiders produce toxic venoms, and some poisons occur naturally in the ground, like asbestos, cadmium, and lead. 

As an additional source of complexity, the ricin gene is part of a multigene family within the castor bean plant that encodes for the production of pro-ricin (the natural ricin precursor), several apparently inactive polypeptides, and a well-studied, structurally related lectin called R. communis agglutinin I (RCA120) (Tregear and Roberts, 1992 Pinkerton et al., 1999 Helmy and Pieroni, 2000). 

Ricin is derived from a common plant, the castor bean (Ricinus communis), and is native to the Mediterranean and Middle East and cultivated elsewhere as an ornamental plant. It is also the source of castor oil, which has many uses in medicine, food, and industry. Ricin is also a highly potent toxin that can kill a person in amounts as small as a few grains of sand. 

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