Toxicology of Plant Lectins

Seidl, Dinah S

Food Poisoning, Handbook of Natural Toxins, Vol. 7: 264-290. Ed. Tu, Anthony T. Marcel Dekker, Inc., Nueva York, EE.UU., 1992.

The presence of heat-labile toxic factors in plant products, mainly legume seeds, makes them unsuitable for human consumption unless they are properly cooked. Among the antinutritional factors that are inactivated by cooking are the lectins or phytohemagglutinins (PHA), which are subject of this chapter.

Lectins were discovered in the last century when Stillmark (1889) presented evidence that the extreme toxicity of castor beans (Ricinus communis) could be attributed to a protein fraction which agglutinated red blood cella and which he called «ricin.» Ehrlich (1891) compared it with the toxic abrin from the jeriquinty seeds (Abrus precatorus) and thus initiated his immunological research on the specificity of antisera obtained by the use of these lectins. This research meant the initiation of many fundamental advances in the knowledge of immunological reactions (Ford, 1913; Lis and Sharon, 1977; Jaffé, 1977; Sharon, 1989).

Landsteiner and Raubitscheck (1908) observed that extracts ofmany edible crude legume seeds would likewise agglutinate red blood cells, but no toxic action was detected at that time. Probably this was due to the relative low toxicity as compared to the very high activity of the above-mentioned lectins.

Today the widespread occurrence of lectins in plant and animal tiasues is well known (Gold and Balding, 1975; Goldstein and Hayes, 1978). Lectins have been reported in more than 800 plant species (Lis and Sharon, 1973).

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