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Precatory Bean

Scientific Name(s): Abrus precatorius L. Family: Fabaceae (beans)

Common Name(s): Precatory bean , love bean , rosary pea , Buddhist rosary bead , crab's eye , jequirity seed , bead vine , black-eyed Susan , prayer beads , weather plant , lucky bean , and numerous other locally used common names. 1 , 2

Uses

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

Dosing

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.

Contraindications

No longer considered safe.

Pregnancy/Lactation

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

Interactions

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.

Toxicology

Precatory bean is highly toxic. Onset of toxicity usually occurs in 1 to 3 days.

Botany

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. 1 , 3

History

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. 2

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. 1 , 4

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

Chemistry

Several indole alkaloids (eg, abrin, hyaphorine, precatorine), triterpenoids, and a new glycoside have been isolated from the plant. 4 , 5 , 6

The protein abrin has been isolated from the seed and is responsible for its toxic effects. It has been described as a single glycoprotein of molecular weight 60,000 to 65,000. 7 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. 8 Both abrin A and C may be subdivided into smaller units of molecular weight of about 30,000.

Another lectin, abrus agglutinin, which is nontoxic to animal cells and exhibits potent agglutinating activity toward erythrocytes, has been described. 9 Abrus seeds also contain a potent proteinase inhibitor. 10

Uses and Pharmacology

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. 11

The A chain (effectomere) is 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. 12

Animal data

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 (IP) to mice pretreated with L1210 leukemia, no increase in lifespan was noted when the compound was administered IV. 13 In another study in mice, abrin injected IP at a dose of 7.5 mcg/kg every other day for 10 days was effective in reducing solid tumor mass. 14

Clinical data

Abrin has been used with some clinical success as an analgesic in terminally ill patients. 15

Ethanolic extracts of the leaves of Abrus possess d-tubocurarine-like neuromuscular blocking activity. 16

Dosage

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

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

Interactions

None well documented.

Adverse Reactions

Fatal poisoning in children has been reported after the thorough chewing of as little as half of 1 seed. 1 , 2 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 have also been reported. 2 , 10

Toxicology

The seeds, roots, and leaves of A. precatorius are all poisonous. 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. 2 Necklaces made of the pierced seeds have been reported to induce dermatitis. 17 Intact seeds remain impervious to gastric fluid and pose less of a toxicologic potential. 18

The onset of toxicity usually occurs in 1 to 3 days; symptoms may persist for longer than 10 days.

Treatment is supportive and symptomatic. Because of the necrotizing action of abrin, gastric lavage or induced emesis should be used cautiously. 2 Measures to maintain circulation include the correction of hypovolemia and electrolyte disturbances. 2 , 3 Alkalinization of the urine to control uremia and enhance toxin excretion has been recommended. 2 , 19

A radioimmunoassay has been developed for abrin. 20

The LD 50 of abrin given IP to mice is 0.04 mcg; 8 5 mg of the alkaloid abrin is reported to be toxic to humans. 17 In goats, ground seeds administered at a dose of 1 and 2 g/kg/day caused death in 2 to 5 days. 21

Bibliography

1. Chevallier A. The Encyclopedia of Medicinal Plants . New York, NY: DK Publishing Inc., 1996.
2. Fernando C. Poisoning due to Abrus precatorius (jequirity bean). Anaesthesia . 2001;56:1178-1180.
3. Lampe KF. AMA Handbook of Poisonous and Injurious Plants . Chicago, IL:American Medical Association; 1985.
4. Evans WC. Trease and Evans' Pharmacognosy , 13 ed. London, England: Bailliere Tindall; 1989.
5. Kim NC, Kim DS, Kinghorn AD. New triterpenoids from the leaves of Abrus precatorius . Nat Prod Lett . 2002;16:261-266.
6. Yadava RN, Reddy VM. A new biologically active flavonol glycoside from the seeds of Abrus precatorius Linn. J Asian Nat Prod Res . 2002;4:103-107.
7. Olsnes S, Refsnes K, Pihl A. Mechanism of action of the toxic lectins abrin and ricin. Nature . 1974;249:627-631.
8. Wei CH, Hartman FC, Pfuderer P, Yang WK. Purification and characterization of two major toxic proteins from seeds of Abrus precatorius . J Biol Chem . 1974;249:3061-3067.
9. Suryakala S, Maiti TK, Sujatha N, Sashidhar RB. Identification of a novel protein adjuvant isolated from Abrus precatorius . Food Agric Immunol . 2000;12:87-96.
10. Joubert FJ. J Biochem Int . 1983;15:1033.
11. Sandvig K, Olsnes S, Pihl A. Kinetics of binding of the toxic lectins abrin and ricin to surface receptors of human cells. J Biol Chem . 1976;251:3977-3984.
12. Lin JY, Chang YC, Huang LY, Tung TC. The cytotoxic effects of abrin and ricin on Ehrlich ascites tumor cells. Toxicon . 1973;11:379-381.
13. Fodstad O, Pihl A. Effect of ricin and abrin on survival of L1210 leukemic mice and on leukemic and normal bone-marrow cells. Int J Cancer . 1978;22:558-563.
14. Ramnath V, Kuttan G, Kuttan R. Antitumour effect of abrin on transplanted tumours in mice. Indian J Physiol Pharmacol . 2002;46:69-77.
15. Chen CC, Lin JY, Hsu CT, Tung TC. Studies on the analgesic effects of abrin and ricin. Taiwan Yi Xue Hui Za Zhi . 1976;75:239-242.
16. Wambebe C, Amosun SL. Some neuromuscular effects of the crude extracts of the leaves of Abrus precatorius . J Ethnopharmacol . 1984;11:49-58.
17. Duke JA. CRC Handbook of Medicinal Herbs . Boca Raton, FL: CRC Press; 1985.
18. Sullivan G, Chavez PI. Mexican good-luck charm potentially dangerous. Vet Hum Toxicol . 1981;23:259-260.
19. Hardin JW, Arena JM. Human Poisoning from Native and Cultivated Plants , 2nd ed. Durham, NC: Duke University Press; 1974.
20. Godal A, Olsnes S, Pihl A. Radioimmunoassays of abrin and ricin in blood. J Toxicol Environ Health . 1981;8:409-417.
21. Barri ME, el Dirdiri NI, Abu Damir H, Idris OF. Toxicity of Abrus precatorius in Nubian goats. Vet Hum Toxicol . 1990;32:541-545.

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