Abrin 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). 

The rosary pea. which is the source of abrin, is common to many tropical areas throughout the world and is sometimes used as an herbal remedy. 

Pathways of metabolism have been outlined which indicate how tryptophan is a source of auxin, niacin, serotonin, ommochrome, and energy. Many other compounds are formed as side-products of these pathways and still others are formed by further reactions. Yet additional pathways remain to be elucidated to describe the formation of gramine (V-dimethyl-indole-3-methylamine), abrine (A -methyltryptophan), the a-hydroxy-tryptophan component of phalloidin, skatole, and possibly other complex compounds containing the indole nucleus. The reactions involved in these transformations include examples of various types of oxidation, transamination, cleavage, elimination, decarboxylation, and condensation as well as cis-trans isomerization. The wealth of biochemical variety already revealed in these studies is a stimulus toward exploration of the still unknown reactions of tryptophan metabolism. 

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