Abrin toxicity

Abrus Abrins (toxic lectins) Abrus precatorius, A. pulchellus Apoptotic (Gal-specific lectin)... 

Surendranath, K., Karande, A.A. (2008). A neutralizing antibody to the A chain of abrin inhibits abrin toxicity both in vitro and in vivo. Clin. Vaccine Immunol. 15 737-43. 

Abrin A and Abrin B [1393-62-0] m, 63,000-67,000. Toxic proteins from seeds of... 

K Sandvig, S Olsnes. (1982). Entry of toxic proteins abrin, modeccin, ricin, and diphtheria toxin into cells. I. Requirement for Ca2+. J Biol Chem 257 7495-7503. 

Due to the extraordinary toxicity of intact ribosome-inactivating toxins like ricin, abrin, and modeccin, purification and handling of these proteins must be done with extreme care. Even dust from crude seed powders or lyophilized proteins should be considered dangerous. During... 

N.A. Seeds Abrin, anthocyanins, indole alkaloids. Root and leaves glycyrrhizin, abrin. This herb is toxic.100 Seeds A contraceptive, aborufacient, treat chronic conjuctivitis. Leaves treat asthma, bronchitis. 

Similar toxic RIPs are found in other plants. Examples are trichosanthin, a type I toxin from the root tubers of Trichosanthes kirilowii (Cucurbitaceae), abrin, a type II toxin from the small brightly coloured red and black jequirity seeds (Abrus precatorius Leguminosae/Fabaceae), and viscumin, a type II toxin from the leaf and stems of mistletoe (Viscum album, Loranthaceae). 

This toxic protein is contained in caster seeds but does not pass into the oil. Similar phytotoxins occur in croton seeds (Crotin) jequirity seeds (Abrin) the bark of the locust tree, Robinia pseudo-acacia (Robin) and in the seeds of some leguminous plants (Phasin). The last is but weakly toxic. Ricin is responsible for the toxic effects on eating castor seeds 5 or 6 of these are fatal to a child, 20 to adults, and 3 or 4 seeds may cause violent gastroenteritis with nausea, headache, persistent vomiting, colic, sometimes bloody diarrhea, thirst, emaciation, and great debility. The symptoms usually do not set in until after several days. More severe intoxications cause small frequent pulse, cold sweat, icterus, and convulsions. Death occurs in 6 to 8 d, from the convulsions or from exhaustion. The fatality rate is about 6%. This low fatality rate is due to the destruction of the poison in the alimentary canal. The treatment would be evacuant and symptomatic. Usually, 3 to 10 d are required to complete recovery. 

The primary clinical targets of immunotoxins are tumors, based on the principle that the MAb will target the toxin to the tumor cells and the highly toxic moiety will then kill the cancer cells. Examples of toxins are ricin, diphtheria toxin and abrin, which are all glycoproteins. Their toxicity is based on their ability to block protein synthesis at the ribosomal protein assembly site. They are normally extremely toxic and not suitable for therapeutic purposes because they induce liver and vascular toxicity, even at low dose levels. 

Abrus Abrin-a Abrus precatorius (Fabaceae) toxic A RAG (rat rRNA A4324 in R/S... 

The mechanisms of toxic action of abrin and ricin are similar. The B-chain attains cell recognition and binding function to facilitate toxin transport across the cell membrane, whereas the A-chain, once internalized by the cell, blocks protein synthesis by catalytically modifying the ribosomes. Both toxins ultimately kill target cells in animal or cell culture models by both necrosis and apoptosis. 

Abrin exerts its toxic action in the same way as ricin. The abrin B-chain avidly binds to a variety of cell types, in particular reticuloendothehal cells which bear the appropriate mannose receptors. The abrin B-chain also binds to the galactosyl-terminated receptors on the cell membrane to allow the entry of the abrin A-chain. Once internalized, the abrin A-chain is transported from the cell membrane to the ribosomes, where it catalytically inactivates the 60S ribosomal subunit by removing adenine from positions 4 and 324 of 28S rRNA, thereby inhibiting protein synthesis and causing cell death (Stripe and Barbieri, 1986). 

Numerous laboratory studies in mammals have demonstrated that ricin and abrin are highly toxic and potentially fatal to animals and humans. Major symptoms of both ricin and abrin poisoning are dependent on the route of exposure, the dose (or number of beans) received, or the content of toxin in the seed (or age of seed). Upon ingestion, toxicity is dependent on the degree of mastication if the bean was... 

Few animal studies exist on the toxicity of orally administered abrin. The majority of reports indicate jequirity seed poisoning in humans, which is discussed later in the chapter. 

Human parenteral toxicity for abrin is approximately 0.1-1 Jig/kg (Romano et al, 2007). However, based on clinical trials on abrin-immunotoxin use for cancer treatment, the human minimum lethal dose by intravenous injection was estimated to be >0.3 Jig/kg without occurrence of serious adverse effects (Gill, 1982). 

Dermal and Ocular Exposure Allergic reaction may occur after handling an intact castor bean plant or exposure to the castor bean dust (Metz et al., 2001 Thorpe et al., 1988). There are no reports of human toxicity by skin contact with abrin. Abrin in powder or mist form can cause redness and pain of the skin and the eyes. 

Fodstad, O., Olsnes, S., Pihl, A. (1976). Toxicity, distribution and elimination of the cancerostatic lectins abrin and ricin after parenteral injection into mice. Br. J. Cancer 34 418-25. Fodstad, O., Johannessen, J.V., Schjerven, L., Pihl, A. (1979). Toxicity of abrin and ricin in mice and dogs. J. Toxicol. Environ. Health 5 1073-84. 

Griffiths, G.D., Rice, P., Allenby, A.C., Bailey, S.C., Scawin, J.W., Rice, P., Upshall, D.G. (1995a). Inhalation toxicology and histo-pathology of ricin and abrin toxins. Inhal. Toxicol. 7 269-88. Griffiths, G.D., Rice, P., Allenby, A.C., Bailey, S.C., Scawin, J.W., Rice, P., Upshall, D.G. (1995b). Protection against inhalation toxicity of ricin and abrin by immunisation. Hum. Exp. Toxicol. 14 155-64. 

Olsnes, S., Refsnes, K., Pihl, A. (1974b). Mechanism of action of the toxic lectins abrin and ricin. Nature 249 627-31. 

Abrin is a plant source Type 2 RIP. It is found in Abrus precatorius (rosary pea, Indian licorice, jequirity bean). The toxicology of abrin is considered to be very similar to ricin. A similar Abrus toxin is pulchellin, produced by A. pul-chellus (Millard and LeClaire, 2008). The rosary pea has been reported to be more toxic than castor beans (Griffiths et al, 1994). Species sensitivity is variable and horses are considered to be the most sensitive. The mature goat is considered to be a more resistant species and 2 g of seed/kg body weight is reported as a lethal dose. The lethal dose for cattle is reported at 600 mg of seed/kg body weight. It is likely that abrin is denatured in the rumen (Burrows and Tyrl, 2001). 

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