Toxin Content of Commercial Castor Cultivars

Abstract The castor plant Ricinus communis L. is the source of castor oil which has numerous uses and is a key chemical feedstock for an array of products from polymers to cosmetics. Although castor was once widely grown throughout the world, the presence of the toxic protein ricin has deterred the re‐introduction of this useful crop. In order to develop a low‐ricin or no‐ricin castor crop, a robust, accurate method for screening castor seed for ricin content is essential. In this study, we validated a sandwich enzyme‐linked immunosorbent assay for the detection of ricin and the homologous Ricinus communis agglutinin (RCA) in castor beans and screened a collection of castor lines including commercial varieties using this assay. Although the average content derived by extracting several seeds provided a fair representation of the ricin content for a given selection, there was enough seed‐to‐seed variation to justify determining the ricin/RCA content of individual seeds. Ricin levels observed ranged from 1.16 to 6.25 % by weight.