Proteins ricin

Other Lethal Agents. There are a number of substances, many found in nature, which are known to be more toxic than nerve agents (6). None has been weaponized. Examples of these toxic natural products include shellfish poison, isolated from toxic clams puffer fish poison, isolated from the viscera of the puffer fish the active principle of curare "heart poisons" of the digitaUs type the active principle of the sea cucumber active principles of snake venom and the protein ricin, obtained from castor beans (See Castor oil). 

Clinically, monoclonal antibodies are also proposed as drug delivery vehicles in certain tumors where specific tumor-associated antigens are expressed. In this context, investigators have found that by conjugating toxins such as the A chain polypeptide of the plant protein ricin or the bacterial toxin from Corynebacterium diphtheriae to monoclonal antibodies specific for certain tumor type, as few as one or two molecules of antibody-toxin conjugate can destroy a tumor cell in vitro. Some success has also been obtained in clinical trials with monoclonal antibody-toxin conjugates. 

Castor oil is derived from the castor plant Ricinus communis). The castor plant has a long and rich history of uses in human society. The oil from the plant is non-digestible, and is commonly known to be a medicinal purgative. The castor bean contains the protein ricin, a substance that is famously toxic in humans [50]. The lack of food value from the castor plant coupled with the issues of toxicity inherent in extraction of ricin has mostly limited the use of castor oil to the industrial sector. 

Castor Ricinus communis (Euphorbiaceae) seed 35-55 ricinoleic (80-90), oleic (4-9), linoleic (2-7), palmitic (2-3), stearic (2-3) emollient base, purgative, soap manufacture Castor seeds contain the highly toxic, but heat-labile protein ricin (see page 434)... 

Examples of cationic material transport on dust include the extremely toxic castor protein (ricin) and the reactor-produced radioisotopes from RDDs. Ricin as purified crystals or powder forms may be disseminated as aerosols (Audi et al. 2005). The localized dispersal of powdered ricin could potentially affect large areas due to transport in dust. Note that the dust in Figure 4.4 is severe enough to limit visibility to less than one quarter of a mile and the street lights are illuminated. Figure 4.5 is... 

A group of plant lectins, such as abrin, ricin, and mod-eccin, are highly toxic to eukaryotic cells. Their mode of action consists of inhibition of protein synthesis by enzymatically inactivating the EF-2 binding region of the 60S ribosomal subunit, whereas the diphtheria toxin inactivates the EF-2 protein itself. Ricin is isolated from castor beans and has a molecular weight of 66,000. Like most plant and bacterial toxic proteins, ricin contains two... 

Griffiths, G.D., Leek, M.D. and Gee, D.J. (1987) The toxic plant proteins ricin and abrin induce apoptotic changes in mammalian lymphoid tissues and intestine. J Pathol, 151, 221-229. 

As a relatively large protein, ricin is unlikely to be extensively absorbed from the gastrointestinal tract. In animal studies, most orally administered ricin was found in the large intestine after 24 h, with only limited systemic uptake (Ishigaro et al, 1992). Dermal absorption of ricin through intact skin is most unlikely to occur,... 

Fodstad 0, Kvalheim G, Godal A et al. (1984). Phase I study of the plant protein ricin. Cancer Res, 44, 862-865. 

CASTOR OIL An age-old home remedy seldom recommended now, castor oil (purge, NEOLOID, others) is derived from the bean of the castor plant, Ricinus communis, which contains two well-known noxious ingredients an extremely toxic protein, ricin, and an oil composed chiefly of the triglyceride of ricinoleic acid. The triglyceride is hydrolyzed in the small bowel by the action of lipases into glycerol and the active agent, ricinoleic acid, which acts primarily in the small intestine to stimulate secretion of fluid and electrolytes and speed intestinal transit. When taken on an empty stomach, as little as 4 mL of castor oil may produce a laxative effect within 1-3 hours however, the usual dose for a cathartic effect is 15-60 mL for adults. 

CgH8N202, Mr 164.16, mp. 201 °C. A pyridine alkaloid from Ricinus communis (Euphorbiaceae). Its content in this plant is 1 % and together with the extremely toxic protein ricin R. is responsible for the toxicity of Ricinus seeds. The biosynthesis of R. proceeds through nicotinamide as an intermediate. 

Castor R. communis (Euphorbiaceae)) is an annual grass from India, and castor oil is expressed from the seeds. A very toxic protein, ricin, is also present in the seed. Ricin is constituted of two protein chains, one of M.Wt. 30,000 Daltons (A chain), and the other M.Wt. 33,000 Daltons (B chain). Ricin is regarded as one of the most toxic substances known [1]. 

Castor bean (seed) contains a highly poisonous protein (ricin), which remains in the seed cake (pomace) after the expression of castor oil. Ricin is reported to contain 18 different amino acids and to have a molec-... 

Originally, type I and type II RIPs were identified based on biological activities. Type II RIPs were discovered more than a century ago, when Stillmark isolated the toxic protein ricin from castor beans. As mentioned, the toxicity of ricin was initially attributed to its agglutination activity for red blood cells and not by ribosome inactivation. Type II RIPs attribute their carbohydrate binding activity to their B-chain, which contains two or possibly three binding sites (Robertus, 1991). The multiple binding sites allow B-chains to aggregate with red blood cells and platelets. 

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