(See original question here.)

ANSWER: Jequirity Bean

The jequirity bean (Abrus precatorius) is a very ordinary looking climbing plant found in warm climates across the world that has very attractively colored seeds that are very toxic. Seeds are often used in jewelry, strung on a line for necklaces or bracelets, or used in rattles because of their hard shell.

Common names: Buddhist Rosary Bead, Crab’s Eyes, Indian Bead, Jequirity Bean, Love Bean, Prayer Bean, Precatory Bean, Rosary Pea, Seminole Bead.

Click to enlarge.

Plant: Abrus p. was introduced to the United States from its native habitat in Asia in the 1930s. It is now considered an ‘undesired invasive weed and cultivation is prohibited in many areas. The plant is an herbaceous perennial climbing plant with small deep green oval leaves (Image 1) and a deep tap root that makes it difficult to eradicate. It has grouped pale pink flowers that bloom from May to September. Seed pods develop later (Image 2) and each contains 3-6 strikingly colored scarlet-red, shiny seeds with a black spot (Image 3). These seeds are so uniform in size and weight (about 7 mm and 1/10th of a gram) they were historically used in India as standard unit (Ratti) for weighing gold.

Exposure: Typical exposure is oral in humans and pet animals (although birds can eat them without injury). Illness and subsequent fatality depend upon the amount, route, and mechanism of exposure. Most described exposures are from seed ingestion (either suicidal or inadvertent) where degree of toxicity depends upon the integrity of the seed’s water impermeable shell. If they were swallowed whole, the toxicity may be limited; if the seed was chewed or if the seed shell was drilled open and strung in a line (e.g., for a bracelet) toxicity may be more profound. Intentional large dose ingestions and parenteral exposures produce severe illness and can be fatal.

Click to enlarge.

Toxicity/Toxin: The entire plant contains abrin, a toxalbumin. This is the most toxic naturally occurring plant poison known. The jequirity seeds have the highest abrin amount per weight-with an estimated fatal human dose between 0.1-1 microgram/kg or about one chewed seed—this is about twice the potency of caster bean’s ricin.

Mechanism: Abrin contains a sulfur-linked A and B chain. The B chain binds to the cell membrane and causes invagination and delivery of the A chain to the ribosomes. The A chain attacks the ribosomes 60S subunit and removes adenine from positions 4 and 324 of the 28S rRNA which stops protein synthesis and causes acute cellular death. Abrin induces cellular death, vascular leak syndrome (tissue edema), and red blood cell agglutination; inhalation of the toxin results in pulmonary edema.