Go to Back

Abrus Precatorius

English: Jequirity, crab's eye, Indian liquorice

Hindi: Rati

Sanskrit: Gunja

The plant has been used in Hindu medicine from very early times, as well as in China and other ancient cultures. The seeds were formerly used in India to weigh gemstones( they are very uniform in size, a single seed equal to 1.75 g or 1 carat ) and in fact the Kohinoor diamond was first weighed by this means. In parts of South America and the Caribbean, necklaces of the seeds were traditionally made for infants to wear as a protection against illness. They are very attractive and hence are popular as jewellery, in rosaries and in noisy toys such as rattles, although this should be avoided because of their toxicity if ingested.

Habitat

A slender vine growing wild in thickets, farms and secondary clearings, generally supported by other plants or a fence. It is native to India, from the Himalayas down to southern India and Sri Lanka, but now grows in all tropical regions throughout the world, most commonly in Florida and Hawaii, Africa, South America and the West Indies.

Botanical description

A twining, climbing shrub, with greenish yellow branches (Plate 1). Leaves 5-17 compound, leaflets obovate or oblong; flowers in crowded racemes, subsessile, pale purple to yellowish. The seeds are slightly smaller than ordinary peas; ovoid scarlet with a black spot round the hilum, or black with a white spot, or uniformly black or white, and glossy. The stout rectangular, bulging, brownish pods ripen by the end of the cold season and curl back on opening to reveal the pendulous red and black seeds, 4-6 in a pod. The root is woody, tortuous and much branched, with a sweet taste, rather like liquorice.

Parts used

Roots, leaves and seeds. Traditional and modem use In Ayurveda the plant is considered beneficial for the hair and the seed extract is used externally in the treatment of ulcers and skin affections. The seeds are poisonous and should only be given to patients after proper processing (e.g. 'Shodhan'), as the toxic protein abrin is then denatured.1 In India a hot water extract of the leaves and roots or seeds is applied topically for eye diseases and taken orally as an emmenagogue. The inhabitants of the Andaman Islands eat the boiled seeds. In tropical Africa, a decoction of the root is taken orally as an antiemetic and for treatment of bilharzia, tapeworm infestation, gonorrhoea, asthma, in chest pain and as an aphrodisiac, and the roots are chewed for snakebite. Seeds are taken orally by several Central African tribes for intestinal worms and as an oral contraceptive. A single dose (200 mg) is said to be effective for 13 menstrual cycles. The water extract of the dried leaves and root is taken orally as a nerve tonic in Brazil and powdered leaves are applied to cuts and swellings.

Ethnoveterinary usage

The leaf is used to treat fowl pox in poultry.

Major chemical constituents

Isotlavonoids and quinones

Abruquinones A,B,C,O,E, F and G. are present in the root and abrusalactone A, abrusgenic acid and methyl abrusgenate'2 in the aerial parts.

Triterpenoids and saponins

Glycyrrhizin and oleanolic acid are found in the rootB and abrusosides A, B, C, 0 and E in the aerial parts.' Abrus-saponins I and II, abrisapogenol, ß -amyrin, squalene, abricin, abridin, cycloartenol, campesterol, cholesterol and ß-Sitosterol have all been found in the seeds.

Proteins

Abrins I, II and III, Abrus precatorius agglutinin (APA) I and APA II20 are present in the seeds.

Alkaloids and nitrogen compounds

Precatorine, trigonelline, choline and abrine are present in the seeds.

Flavonoids and anthocyanins

Abrectorin, dimethoxycentaureidin-7 -0-rutinoside, precatorins I, II and III, and xyloglucosyl-delophinidin and p-coumaroyl-galloyl-glucosyl-delphinidin have been isolated from the seeds.

Carbohydrates

Galactose, arabinose, and xylose25 are present in the aerial parts.

Medicinal and pharmacological activities

Antitumour activity: Agglutinin protein purified from the seeds of Abrus precatorius showed high anti tumour activity. Injection of 1 ng of abrinA into mice bearing Meth-A tumour inhibited the tumour growth by 90%, with abrinA having a higher affinity constant for sarcoma cells than abrin B. Binding inhibition studies with sugars suggested that abrins A and B have different binding sites, although both abrins inhibited sarcoma 180 in mice. Abrin A was more toxic than abrin B. Phytoagglutinins had agglutinating activity in murine ascites cells and inhibited the growth of Yoshida sarcoma cells.

Immunomodulating activity: The abrins have been used in the formulation of antigenic injections with the ability to increase both cellular and humoral immune responses but without causing necrosis and swelling at the injection site. Thus, a mixture of 15 ng abrin and l11g bovine serum albumin (BSA), when administered by injection, provided a stronger immune response to the antigen than when abrin and BSA were administered separately. The activity of abrin to increase the humoral immunity was strongest at the 10 ng dose. Abrin also enhanced antitumour immunity.

Antifertility activity, males: An alcoholic extract of the seed produced a lowering of sperm motility, but no effect on concentration, after 60 days of feeding to male rats. Scanning electron microscopic studies on sperm morphology revealed decapitation, acrosomal damage and formation of bulges on the mid-piece region. Biochemical studies on epididymal spermatozoa indicated alterations in energy and or oxidative metabolism, as evidenced by a fall in succinate dehydrogenase and ATPase levels. The average number of implantation sites in females, after mating with the treated male rats, also markedly declined. However, a significant increase in serum testosterone levels was noted, suggesting that the decrease in fertility rate in treated animals was due to reduced sperm motility, metabolism and altered morphology in the epididymis rather than changes in hormone levels. Dose¬dependent degenerative changes in testicular weight, sperm count, later stages of spermatogenesis and Leydig cells were observed in the testis of rats given the steroidal fraction of the seeds. This may be a result of a decrease in the activity of enzymes such as hydroxysteroid ehydrogenases, glucose-6-phosphate and sorbitol dehydrogenases and leucine aminopeptidase or an indirect influence at the pituitary leve)," In another study, oral administration of a 50% ethanol extract of the seeds (250 mglkg) in albino rats for 30 and 60 days induced an absolute infertility in males, which was reversible. Suppression of sperm motility in the cauda epididymis was the most pronounced effect of the treatment. Histological and other observations on the testes and para reproductive tissues appeared normal, while the protein, sialic acid, acid phosphatase and succinic dehydrogenase levels were significantly depleted.

Methanol extracts of the seeds showed an inhibitory effect on the motility of washedhuman spermatozoa, which was essentially irreversible. At the highest concentration tested (20 mg/ml), the onset of the antimotility action was almost immediate and the functional integrity of the plasma membrane and viability impaired. In contrast, with a lower concentration (5 mg/ml), such effects were not evident. It was concluded that at the lower concentrations, the antimotility action may have resulted from a rise in intracellular calcium (not via influx),a decline in cAMP content and/or enhanced generation of reactive oxygen species.

Antifertility activity, females: A partially purified fraction, injected precoitum or immediately postcoitum to female rats, induced 100% sterility, but was ineffective when injected 2-5 days postcoitum. Isolated abridin induced 100% sterility in rats when injected one day pre- or postcoitum. The alcoholic extract of the seeds of A. precatorius when injected for 10-12 days disturbed the oestrus cycle of the rat and induced sterility when injected for five consecutive days prior to mating. Similar activity was recorded in the unsaponifiable fraction of the extract. This altered the cyclic rhythm of the animals, lowered plasma oestradiol and progesterone levels and decreased ovarian weight, possibly by altering ovarian steroid metabolism. The petroleum ether and alcoholic extracts of the roots, given 1-5 days postcoitus, completely prevented nidation and the alcoholic extract also showed anti-oestrogenic activity when given simultaneously with 0.05 pg oestradiol. The oral LDso of the alcohol extract was 2 g/kg.

Abortifacient activity: An aqueous suspension of the seeds induced abortion in 51 % of rats, when orally administered postcoitally at the daily dose of 125 mg/kg from day a to day 10. The activity was reduced when the same dose was administered from day 6 to day 15.35 Antiplatelet activity: The isoflavoquinones and abruquinones A, Band D significantly inhibited platelet aggregation. The ICso values of abruquinones A and B for the inhibition of the platelet aggregation induced by arachidonic acid and collagen were less than 5 pg/ml, and that of abruquinone D was less than 10 pg/ml for aggregation induced by arachidonic acid.

Antiinflammatory and antiallergic activity: Abruquinones A, B, D and F showed strong antiinflammatory and antiallergic effects. The ICsofor the inhibition of superoxide formation was less than 0.3 pg/ml for the inhibition of the release of both P-glucuronidase and lysozyme from rat neutrophils and less than 1 pg/ml for the release of p-glucuronidase and histamine from mast cells." Saponins isolated from the aerial parts, and their acetates, exhibited antiinflammatory activity in the croton oil ear model. Polymyxin B-induced hind paw oedema was suppressed by abruquinone A, in normal as well in adrenalectomised mice. Unlike dexamethasone, abruquinone A did not increase the liver glycogen content in fasting adrenalectomised mice. It reduced the volume of exuded plasma in neurogenic inflammation and passive cutaneous anaphylactic reaction. Histamine, serotonin, bradykinin and substance P-induced plasma extravasation in ear oedema was also suppressed, to a greater extent than with diphenhydramine and methysergide. These and other results suggested that the antiinflammatory effect of abruquinone A is mediated partly via the suppression of the release of chemical mediators from mast cells and partly via the prevention of vascular permeability changes caused by mediators.

Molluscicidal activity: In vivo and in vitro sublethal exposure to abrin and glycyrrhizin inhibited acetylcholinesterase, lactic dehydrogenase and acid and alkali phosphatase activity in the nervous tissue of Lymnaea acuminata. Succinic dehydrogenase activity was increased during the in vivo treatment although in vitro exposure had no significant effect. Abrin and glycyrrhizin also significantly decreased levels of protein, free amino acid, DNA and RNA and abrin caused a reduction in phospholipid levels with a simultaneous increase in the rate of lipid peroxidation in the treated snails.

Insecticidal activity: Abrine produced a dose-dependent depletion of sugars and protein content in mealy bugs and also in lipids at higher concentrations, suggesting that abrine could have a useful effect on reducing the population of this insect.

Use as a sweetening agent: Abrusosides A, B,C and 0 have been suggested as sugar substitutes in foods and pharmaceuticals. Preliminary safety studies indicate a lack of acute toxicity in mice and mutagenicity. In sensory tests the abrusosides were 30-100 times sweeter than 2 % sucrose. Abrusoside 0 had a lingering sweetness lasting 30 minutes.

Antibacterial activity: The ethanol (95%) extract was active against Escherichia coli and Staphylococcus aureus. Antidiarrhoeal activity: A fraction obtained from the dried seeds was active against castor oil-induced diarrhoea in rats.

Safety profile

Fatal poisoning in children has been reported after the thorough chewing of one seed. They are highly toxic and cause severe stomach cramping accompanied by nausea, severe diarrhoea, cold sweats, tachycardia, coma and circulatory collapse. The LOso of abrin (IP) in mice was found to be 8.34 mg/kg. Prolonged administration of abrin in mice produced initial anaemia, which normalised at the end of the experiment, and an increase in white blood cell count. Intraperitoneal injection of abrin to pregnant rats produced both maternal and fetal changes, whereas abrin given orally produced significant fetal effects only:sThe ethanol-water (1: 1) extract of the aerial parts was much less toxic (when administered to mice the LOso was> 1 g/kg body weight46) and the ethanol (95 %) extract of the dried leaves, administered to chickens, produced an LOso of 12 mglkg body weight.

Dosage