Abrin

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. 

from jequirity beans (Abrus precatorius), resembles ricin so closely in its action that the difference was established only when it was noted that immunity against one did not constitute immunity against the other. 

This contains, besides ordinary fats, about 10% of croton-resin, the active component producing the local and systemic effects of the oil. It is destroyed by boiling with alkalis. Croton oil is the most violent of all cathartics, 1/2 to 1 drop producing burning in the mouth and stomach, often vomiting, and after 1/2 to 3 h, several extensive fluid evacuations, with much colic and tenesmus. It was formerly used in extreme cases of constipation, and in unconscious patients (uremic and 

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In contrast, investigation of the effect of ligands on the endo-exo selectivity of the Diels-Alder reaction of 3.8c with 3.9 demonstrated that this selectivity is not significantly influenced by the presence of ligands. The effects of ethylenediamine, 2,2 -bipyridine, 1,10-phenanthroline, glycine, L-tryptophan and L-abrine have been studied. The endo-exo ratio observed for the copper(II)-catalysed reaction in the presence of these ligands never deviated more than 2% from the endo-exo ratio of 93-7 obtained for catalysis by copper aquo ion. 

Table 3.4. Enantiomeric excess and reaction times of the copper(L-abrine)-catalysed Diels-Alder reaction of3.8cwith3.9in different solvents at 0 C.

Figure 3.4. TJV-vis absorption spectra of 3.10c in water and in water containing 3.0 mM of Cu (glycine) complex, 3.0 mM of Cu(N-methyl-Ftyrosine) and 3.0 mM of Cu(L-abrine).

The influence of a large number of oc-amino acids on the values of and k at have been determined. These a-amino acids included glycine, L-valine, L-leucine, L-phenylalanine, L-tyrosine, L-tryptophan, NOrmethyl-L-tryptophan (L-abrine), N-methyl-L-tyrosine, N,N-dimethyl-L-tyrosine and p -me thoxy-N-me thyl -L -phenyl al anine. 

We have investigated the effect of solvents on the enantioselectivity. It turned out that water (74% ee) favours the enantioselectivity of the Cu (L-abrine) catalysed Diels-Alder reaction between Ic and 2 as compared to chloroform (44% ee), ethanol (39% ee), THF (24% ee) and acetonitrile (17% ee). The... 

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

Abrine, This substance is not well named as it is liable... 

Abrine, 484 Abrotine, 772 Abrtis precatorius, 484 Abuta spp., 371 Acacia spp., 771 Acetylcholine, 262, 518 Acetylomithine, 170, 171, 172 Achillea spp., 779 Achilleine achilletine, 779 Acolyctine, 686 Aconine, 673, 675, 679, 685 Aconines, nuclear structure, 693 Aconite alkaloids, 673 Aconitine, 673, 674, 775 oxidation products, 676 Aconitines, pharmacological action, 690 Aconitinone, 676 Aconitoline, 675... 

Indole Group. Abrine, Gramine, Calyeanthine Alkaloids of... 

Tryptophan (15) and its substituted derivatives also react with aldehydes to give l,2,3,4-tetrahydro-jS-carboline-3-carboxylic acids (17), Acetaldehyde and benzaldehyde yield the expected products with the amino acid and its A -methyl derivative (abrine). ... 

The complex obtained from commercially available chiral a-amino acids (AA) with Cu + ion induces asymmetry in the Diels-Alder reaction of 31 (R = H) with 32. By using 10% Cu(II)-AA (AA = L-abrine) the cycloaddition occurs e/iJo-stereoselectively in 48 h at 0°C with high yield and with acceptable enantioselectivity ee = 1A%). This is the first example of enantioselective Lewis-acid catalysis of an organic reaction in water [9b]. 

Copper-complexes prepared with other type of N-chelating ligands have been also prepared and evaluated as catalysts for the Diels-Alder reaction. Eng-berts et al. [103] studied enantioselective Diels-Alder reaction of 3-phenyl-l-(2-pyridyl)-2-propen-l-one with cyclopentadiene in water (Scheme 39). By using coordinating chiral, commercially available a-amino-adds and their derivatives with copper salts as catalysts, they obtained the desired product with yields generally exceeding 90%. With L-abrine (72 in Scheme 39) as chiral moiety, an enantiomeric excess of 74% could be achieved. Moreover, the catalyst solution was reused with no loss of enantioselectivity. 

In addition to the aforementioned effects on paracellular drug transport, Ca2+ also plays an important role in the transcytosis of macromolecules. The entry of the plant lectins abrin, modeccin, and viscumin into Vero cells was inhibited in a Ca2+-free medium a well as in a Ca2+-containing medium containing verapamil and Co2+, both inhibitors of Ca2+ [217], Ca2+ is therefore required at a stage after the binding of the above lectins, perhaps in the fusion and exocytosis of membrane vesicles. 

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. 

Asymmetric reactions using chiral copper Lewis acids are also performed in aqueous media. It has been reported that an asymmetric Diels-Alder reaction proceeds smoothly in water using Cu(OTf)2 and abrine as a chiral ligand (Scheme 49).214 The Cu -bis(oxazoline) system is effective in asymmetric aldol reactions in an aqueous solvent such as water/ethanol and even in pure water.215... 

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... 

Eiklid, K., Olsnes, S., and Pihl, A. (1980) Entry of lethal doses of abrin, ricin, and modeccin into the cytosol of Hela cells. Exp. Cell Res. 126, 321-326. 

Olsnes, S. (1978) Binding, entry, and action of abrin, ricin, and modeccin. In Transport of Macromolecules in Cellular Systems (S.C. Silverstein, ed.), pp. 103-116. Dahlem Konferenzen, Berlin. 

National Institute for Occupational Safety and Health. "Emergency Response Card for Abrin." Interim Document, March 24, 2003. 

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