Abrin-a structure. The A chain is shown in blue and the B chain in olive.
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Abrin is an extremely toxic toxalbumin found in the seeds of the rosary pea (or jequirity pea), Abrus precatorius. It has a median toxic dose of 0.7 micrograms per kilogram of body mass when given to mice intravenously (approximately 31.4 times more toxic than ricin, being 22 micrograms per kilogram). 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 is a ribosome inhibiting protein like ricin, a toxin which can be found in the seeds of the castor oil plant, and pulchellin, a toxin which can be found in the seeds of Abrus pulchellus. Abrin is classed as a "Select Agent" under U.S. law.