Castor seeds

Castor oil (qv) contains a predominance of ricinoleic acid which has an unusual stmcture inasmuch as a double bond is present in the 9 position while a hydroxyl group occurs in the 12 position. The biochemical origin of ricinoleic acid [141-22-0] in the castor seed arises from enzymatic hydroxylation of oleoyl-CoA in the presence of molecular oxygen. The unusual stmcture of ricinoleic acid affects the solubiUty and physical properties of castor oil. 

Chen, . X., Y. S. Ding, and L. G. Chen. 1994. Experimental study on the processed drug of castor seeds in the therapy of pulmonary carcinoma. Chung Kuo Chung Yao Tsa Chih 19 726-727, 762. 

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)... 

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. 

Seeds of Areca catechu (betel nut) (Palmae) contain the simple jV-methyltetrahydropyridine 3-carboxylic acid (jV-methyl-A -tetrahydronicotinic acid) arecaidine and arecoline (arecai-dine methyl ester) (Section 1, Appendix) that are mACh-R agonists and accordingly parasympathetic stimulants. Betel nut also yields guvacine (A -tetrahydronicotinic acid) that is an anti-epileptic GABA transport inhibitor. Conversely the jV-methyl dihydropyridone derivative ricinine from seeds of Ricinus communis (castor seed) (Euphorbiaceae) is a stimulatory agonist acting at the benzodiazepine site of the GABA(A) receptor. 

Klaim, G.J, Jaeger, J.J. (1990). Castor seed poisoning in humans a review Technical Report 453. Letterman Army Institute of Research, San Francisco, CA, January. 

Waller, G.R., Negi, S.S. (1958). Isolation of ricin, ricinine, and the allergenic fraction from castor seed pomace from two different sources. J. Am. Oil Chem. Soc. 35 409-12. 

Lindqvist Y, Huang W, Schneider G, Shanklin J. Crystal Structure of h stearoyl-acyl carrier protein desaturase from castor seed and its relationship to other di-iron proteins. EMBO J. 199 15 4081 092. 

Ricin as a potential biological threat agent has received much popular press. In 2003, suspects were arrested in London for making ricin from castor seed in their apartment (Risen and van Natta 2003). The popular press has speculated that if ricin were made, it could be used to contaminate food in military mess halls. All of these instances indicate that biological and chemical materials may be a potential terrorist weapon to compromise the safety of the military and civilian food supply or other vulnerable areas. Given the extreme toxicity of ricin, the relative ease with which it can be obtained, and the fact that references to its use have been discovered in terrorist haunts, the ability to accurately and precisely detect ricin is a critical need. 

Several aspects of ricin, including its significant toxicity, past association with chemical warfare, and wide availability in ton quantities from castor seed meal, have contributed to the international regulation of the toxin as a potential weapon of mass destniction. Ricin is currently monitored as a Schedule 1 toxic chemical under the Convention on the Prohibition of the... 

The total quantity of ricin produced or stored within castor seeds depends on the genetic composition of the plant and the growth conditions. As a general guide, published purification methods may yield 1-2 mg of ricin/g of castor seed meal starting material (Ishiguro et al., 1964a Olsnes and Pihl, 1977 Parker et al., 1996). 

Animal Lethal Dose of Ingested Castor Seed (g/kg) Lethal Dose of Injected (i.m.) Ricin (p.g/kg) Lethal Dose of Injected (i.p. or i.v.) Ricin (pig/kg) Relative Resistance to Injected (s.c.) Ricin ... 

Average lethal dose of castor seed p.o. from a single study of Mieszner and colleagues (Mieszner and Rewald, 1909 Hunt etal.. 1918 Balint, 1974). 

The susceptibility of different animal species to poisoning with castor seed has been shown to vary by as much as 100-fold (Table 17.2) (Hunt et al., 1918 Balint, 1974). It is unclear to what extent this reflects differences in the amount of actual toxin ingested owing to variations in seed content, digestive processes, or protective regurgitation, versus more subtle innate or biochemical mechanisms of resistance to ricin in some animals. 

Signs and Symptoms Reported to Result from Castor Seed Ingestion... 

Hunt et al., 1918 Kopferschmitt et al., 1983 Wedin et al., 1986 Franz and Jaax, 1997 Palatnick and Tenenbein, 2000). Although humans may be particularly susceptible to ricin poisoning, there is little basis for an informed estimate because of the great variation in the amount of toxin contained in castor seeds, as well as variations in the circumstances of poisoning (Hunt et al., 1918 Balint, 1974). There are also wide differences expected in the amount of toxin released... 

Whole castor seeds contain oil, phytochemicals, and other potentially purging components that may induce protective vomiting or otherwise reduce Gl absorption of ricin in humans. One must recognize, therefore, that the highly successful clinical outcome of treating accidental or intentional cases of oral poisoning with castor seeds may not accurately predict the human morbidity or mortality associated with consumption of pure or stabilized ricin. 

Although it is less common than is the castor seed allergic syndrome, workers chronically exposed to subacute ricin or other RIPs may develop Type I allergies directly against the toxins allergies to purified RIPs can be demonstrated by immune sensitization and IgE induction (Hunt et al., 1918 Forster-Waldl et al., 2003 Szalai et al., 2005). 

A 20 year old man allegedly attempted suicide by injection (s.c.) of an unknown amount of ricin from crude castor seed extract (Targosz et al., 2002). The victim entered the hospital about 36 h after injecting the toxin with symptoms of nausea, dizziness, weakness, chest and abdominal pain, and myalgia with paraesthesia of the extremities. Signs included hypotension, anuria, metabolic acidosis, and a bleeding diathesis. Hepatorenal and cardiorespiratory failure preceded death from an asystolic arrest approximately 54 h after injection. 

Sublethal effects of injected ricin have been documented in isolated case reports, and are difficult to distinguish from those of many other toxic or infectious agents. A 36 year old chemist who allegedly injected himself (i.m.) with an unknown amount of ricin prepared from homogenized castor seed, for example, complained of headache and rigors approximately 10 h later, then developed anorexia and nausea, a sinus tachycardia, erythematous areas around the puncture wounds, and local lymphadenopathy at the injection sites (Fine et al., 1992). 

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