Abrin periodate

Ricin and related type 2 RIP plant toxins are comparably lethal to laboratory mice under controlled conditions (Table 17.3). Variations in the LD50 values for a single toxin reported by different laboratories are comparable with variations among different toxins. Few controlled animal studies are available for several of these toxins, and comparisons among laboratories are limited by differences in toxin preparations, animal strains, and methodologies employed. The postexposure observation period is a particularly important variable for example, the literature values for the acute toxicity of abrin vary by 80-fold depending on whether intoxicated animals are observed for 24 or 48 h after exposure (Dickers et al., 2003). 

Phytohaemagglutinins.—Abrin, ricin, and their isolated A and B chains have been subjected to various chemical treatments and the effect of these on the biological activity of the lectins assessed. Reductive methylation, periodate oxidation, or succinylation of abrin or ricin reduced the toxicity and haemagglutinating ability of the former but not the latter. Treatment with A-acetylimidazole or A-bromosuccinimide resulted in strongly reduced toxicity of abrin and ricin, while 2-hydroxy-5-nitrobenzyl bromide had much less effect. 

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