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Precatory Bean

Scientific Name(s): Abrus precatorius L.
Common Name(s): Bead vine, Black-eyed Susan, Buddhist rosary bead, Crab's eye, Habbat Al-Arus, Jequirity seed, John Crow beads, Love bean, Lucky bean, Prayer beads, Precatory bean, Rosary pea, Weather plant

Medically reviewed by Last updated on Dec 21, 2021.

Clinical Overview


The precatory bean has experienced some success as an analgesic in terminally ill patients.


Precatory bean is a dangerous poison; one seed if thoroughly chewed has been claimed to be fatal to a child; however, the tough, impermeable seed coat reduces its toxic potential.


No longer considered safe.


Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.


None well documented.

Adverse Reactions

Because of the irritant effects of abrin on the GI mucosa, ingestion of precatory beans causes severe stomach cramping accompanied by nausea, vomiting, severe diarrhea, cold sweat, and fast pulse. Coma, circulatory collapse, acute renal failure, and hepatotoxicity also have been reported.


Precatory bean is highly toxic. Onset of toxicity usually occurs in 1 to 3 days. It is most commonly ingested accidentally by children.

Scientific Family

  • Fabaceae (pea)
  • Leguminosae (bean)


A. precatorius is native to southeast Asia and is now found in other tropical and subtropical regions. It is commonly found in Florida and Hawaii where it grows as a slender vine generally supported by other plants or a fence. The plant has clusters of pink flowers, and its compound leaves are sensitive to light, drooping at night and on cloudy days. The fruit splits open as it dries to reveal 3 to 5 hard-coated, brilliant scarlet (or rarely white) seeds with a small black spot at the point of attachment. This spot helps identify the seeds, which are sometimes confused with Rhynchosia, in which the black and red colors are reversed. Seeds of A. precatorius may also be confused with those of Ormosia, also a toxic member of the Fabaceae.Chevallier 2001, Garaniya 2014, Quattrocchi 2012, USDA 2016 A synonym is Abrus abrus L.


The precatory bean has found widespread use as an art object and ornament. The colorful, hard beans have been used as pendants, rosaries, rattles, necklaces, and in toys such as noise shakers.Fernando 2001

All parts of the plant have been used in traditional medicine. Dilute infusions have been used in South American and African folk medicine for the treatment of ophthalmic inflammations such as conjunctivitis. Precatory beans have been used medicinally to hasten labor, stimulate abortion, and also have found some use as an oral contraceptive in traditional medicine. The seeds also have been used to treat fever in Chinese medicine. The leaves and roots of the plant have been used in Ayurvedic medicine for treatment of asthma, bronchitis, and other respiratory conditions.Chevallier 2001, Evans 1989, Garaniya 2014

Because of the great potential for toxicity, the use of this plant is not recommended.


Several indole alkaloids (eg, abrin, hyaphorine, precatorine), triterpenoids, and glycosides have been isolated from the plant,(Evans 1989, Garaniya 2014, Kim 2002, Yadava 2002) including the phenylpropanoid, lonchocarpine.(Jeong 2017)

The protein abrin has been isolated from the seed and is responsible for its toxic effects. It is one of the most deadliest poisons in the world, almost twice as potent as the structurally similar ricin (Ricinus communis).(Alhamdani 2015, Jang 2010) It has been described as a single glycoprotein of molecular weight 60,000 to 65,000.(Olsnes 1974) Two proteins of differing amino acid composition have been purified from precatory beans, designated abrin A and C. Abrin C exhibits more potent hemagglutination activity than abrin A.(Wei 1974) Both abrin A and C may be subdivided into smaller units of molecular weight of about 30,000. Abrin is a type 2 ribosome inactivating protein. The toxin is composed of 2 chains (A and B) with distinct functions. The B chain (the haptomere) binds to galactose units of cell surface carbohydrates.(Sandvig 1976)

Another lectin, abrus agglutinin, which is nontoxic to animal cells and exhibits potent agglutinating activity toward erythrocytes, has been described.(Suryakala 2000) Abrus seeds also contain a potent proteinase inhibitor.(Joubert 1983)

Uses and Pharmacology

Animal and in vitro data

Limited studies have been conducted in animals. Abrin has been used as a molecular probe to investigate cellular function. It has also been evaluated in the treatment of experimental cancers. Although effective when given intraperitoneally to mice pretreated with L1210 leukemia, no increase in lifespan was noted when the compound was administered IV.(Fodstad 1978) In another study in mice, intraperitoneal abrin over 10 days was effective in reducing solid tumor mass.(Ramnath 2002)

Antidiabetic effects of a methanol leaf extract have been described in rodents,(Umamahesh 2016) whereas a 70% ethanol seed extract demonstrated some mild inhibition of pancreatic lipase.(Elbashir 2018)

Ethanolic extracts of the leaves of Abrus possess d-tubocurarine-like neuromuscular blocking activity.(Wambebe 1984)

Antioxidant activity of the ethanolic extract of A. precatorius is similar to the positive control trolox (water-soluble derivative of vitamin E) in vitro(Elbashir 2018) and has also been observed in drug-induced nephropathy and neuroinflammation murine models.(Falayi 2018, Jeong 2017)

Renal protection from gentamicin was demonstrated by a methanol stem bark extract of A. precatorius in rats. Significant improvements were seen in several renal parameters (ie, serum creatinine, urea) as well as antioxidant enzymes and anti-inflammatory pathway signaling (ie, NF-kappaB).(Falayi 2018)

Inhibition of neuroinflammation has been observed in vitro and in vivo with lonchocarpine isolated from A. precatorius roots via modulation of most inflammatory genes that resulted in suppression of tumor necrosis factor-alpha, inducible nitric oxide synthase, cyclooxygenase-2, interleukin [IL]-1beta, IL-6, and NF-kappaB signaling, plus increased expression of IL-10.(Jeong 2017) Meanwhile, an ethanolic extract of A. precatorius leaves produced significant improvement in asthma-related inflammatory effects (ie, paw edema, histamine-induced bronchoconstriction) in several animal models.(Taur 2017)

Clinical data

Research revels no clinical data as toxicity of the plant has precluded clinical studies. Detoxification of the plant has been studied, potentially facilitating clinical study in the future.(Dhoble 2014)


Clinical studies are lacking for any therapeutic application. Precatory bean is a dangerous poison; one seed if thoroughly chewed has been claimed to be fatal to a child, however the tough, impermeable seed coat reduces its toxic potential.

Pregnancy / Lactation

Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.


None well documented.

Adverse Reactions

Because of the irritant effects of abrin on the GI mucosa, ingestion of precatory beans causes severe stomach cramping accompanied by nausea, vomiting, severe diarrhea, cold sweat, and fast pulse.Fernando 2001, Joubert 1983 Necklaces made of the pierced seeds have been reported to induce dermatitis.Duke 2003


The seeds, roots, and leaves of A. precatorius are all poisonous. The A chain (effectomere) of the constituent abrin is reportedly responsible for the toxic activity. Once inside the cell, the A chain migrates to the 60S unit of the ribosome, acting to inhibit further protein synthesis. Abrin has a strong inhibitory effect on protein synthesis, moderate inhibitory effect on DNA synthesis, and little effect on RNA synthesis.(Wei 1974)

The LD50 of abrin given intraperitoneally to mice is 0.04 mcg;(Wei 1974) 5 mg of the alkaloid abrin is reported to be toxic to humans.(Duke 2003) In goats, ground seeds administered at a dose of 1 and 2 g/kg/day caused death in 2 to 5 days.(Barri 1990) The estimated fatal human dose is 0.1 to 1 mcg/kg, almost half that of ricin.(Alhamdani 2015) In children as little as half of one seed has been fatal.(Chevallier 2001, Fernando 2001)

Coma, circulatory collapse, acute renal failure, and hepatotoxicity have been reported.(Fernando 2001, Joubert 1983) Neurologic symptoms have been reported(Patil 2016) as well as fatalities.(Chevallier 2001, Fernando 2001, Jang 2010, Patil 2016) The toxin is released when the hard outer covering is pierced, thus allowing absorption into the intestinal secretions, by chewing or drilling holes in the seeds for beadwork, ornaments, or jewelry. Intact seeds remain impervious to gastric fluid and pose less of a toxicologic potential.(Sullivan 1981)

The onset of toxicity may be delayed up to 3 days; symptoms may persist for longer than 10 days.(Alhamdani 2015)

Treatment is supportive and symptomatic. Because of the necrotizing action of abrin, gastric lavage or induced emesis should be used cautiously.(Fernando 2001, Patil 2016) Measures to maintain circulation include the correction of hypovolemia and electrolyte disturbances. Alkalinization of the urine to control uremia and enhance toxin excretion has been recommended.(Alhamdani 2015, Fernando 2001, Hardin 1974, Jang 2010)

Recently, studies have demonstrated protection against abrin intoxication with anti-abrin antibodies(Mechaly 2018) and a vaccine-like chimeric protein of abrin A chain combined with an A. precatorius agglutinin.(Tiwari 2017) The chimera vaccine as well as serum containing the antibodies led to 100% survival of all mice immunized against lethal doses of abrin.(Tiwari 2017) Similarly, anti-abrin antibody treatment administered 6 hours after lethal abrin exposure in mice led to a 95% survival rate.(Mechaly 2018)

A radioimmunoassay has been developed for abrin.(Godal 1981)

Index Terms

  • Abrus abrus L.



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This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

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