**3. History of plant lectins**

Lectin, agglutinin, and hemagglutinin are synonym of lectin's names. The first time that Lectin was descript back to 1888 by Stillmark, who study the lectin from the seeds of castor bean (about Ricin A toxic ferment from the seeds of *Ricinus communis* L. and some other Euphorbiaceae Species). He linked the toxicity of castor beans to the occurrence of a hemagglutinaing protein factor. For along time before it was definitely demonstrated that Stillmark's "ricin" was a mixture of a weakly agglutinating protein toxin (still known as ricin) and a nontoxic agglutinin (*Ricinus communis* agglutinin, or RCA). The first evidence for this came from studies by Kabet et al. during World War II. They found by immunochemical methods that the toxic and hemagglutinating properties of "ricin" were due to different substances. Only in 1960 was separation of the two substances achieved by Funatsu, and know that ricin came to the attention of the general public in 1978, following its use as a weapon in the notorious, politically motivated "umbrella murder". The dimensions of the hole, led to the conclusion that ricin was the killing agent, since very few poisons are sufficiently potent to kill a man at such a minute amount. In 1898 Elfstrand introduced for the first time the term "hemagglutinin" as a common name for all plant proteins that cause clumping of cells. The idea that toxicity is an intrinsic property of lectin was abandoned in the beginning of the century after have a report for the first time the present of nontoxic lectin in the legumes *Phaseolus vulgaris* (bean), *Pisum sativum* (pea), *Lens culinaris* (lentil), and *Vicia sativa* (vetch). Following this work more nontoxicity plant hemagglutinin has been found. Eventually, it became Evident that lectin is widespread in the plant kingdom and that toxicity is the exception rather than the rule (Van Damme et al., 1995).

The next milestone in the history of plant lectin was a term. When have been found that some hemagglutinin exhibit a clear preference toward erythrocytes of a particular human blood group within the ABO system (Boyd and Reguera, 1949; and Renkonen, 1948). The term "lectin" originally introduced to emphasize the selective agglutination behavior of some hemagglutinin, it was later applied to all proteins with agglutinating activity. "hemagglutinin" is certainly a more appropriate term than lectin because it refers to the capability of a protein to agglutinate erythrocytes but does not take into account that most lectin can also agglutinate other cells. Hence, the term agglutinin should be preferred. In the absence of a clear consensus, the term lectin is actually most commonly used, but agglutinin and hemagglutinin still persist as synonyms.

The current confusion in the terminology of lectin to a great degree is result in the fact that different names have been introduced before the mechanism causing the macroscopically visible agglutination activity was understood in molecular terms. In 1936 already observed that cane sugar inhibited the agglutination activity of Concanavalin A (Con A) (Summer and Howell, 1936). It was demonstrated in 1952 that the agglutination properties of lectin is base on a specific sugar-binding activity (Watkins and Morgan, 1952). As soon as lectin was recognized as carbohydrate-binding protein they could be distinguished from other proteins on the basis of a well-defined functional criterion. For this reason lectin is now considered initially as carbohydrate-binding proteins rather than as (hem) agglutinin.

extracted and intensively characterized from several monocot families: Alliaceae, Amaryllidaceae, Araceae, Bromeliaceae, Iridaceae, Liliaceae, and Orchidaceae (Wood et al., 1999). For example, *Narcissus pseudonarcissus* (daffodil) and *Scilla campanulata* (bluebell)

Lectin, agglutinin, and hemagglutinin are synonym of lectin's names. The first time that Lectin was descript back to 1888 by Stillmark, who study the lectin from the seeds of castor bean (about Ricin A toxic ferment from the seeds of *Ricinus communis* L. and some other Euphorbiaceae Species). He linked the toxicity of castor beans to the occurrence of a hemagglutinaing protein factor. For along time before it was definitely demonstrated that Stillmark's "ricin" was a mixture of a weakly agglutinating protein toxin (still known as ricin) and a nontoxic agglutinin (*Ricinus communis* agglutinin, or RCA). The first evidence for this came from studies by Kabet et al. during World War II. They found by immunochemical methods that the toxic and hemagglutinating properties of "ricin" were due to different substances. Only in 1960 was separation of the two substances achieved by Funatsu, and know that ricin came to the attention of the general public in 1978, following its use as a weapon in the notorious, politically motivated "umbrella murder". The dimensions of the hole, led to the conclusion that ricin was the killing agent, since very few poisons are sufficiently potent to kill a man at such a minute amount. In 1898 Elfstrand introduced for the first time the term "hemagglutinin" as a common name for all plant proteins that cause clumping of cells. The idea that toxicity is an intrinsic property of lectin was abandoned in the beginning of the century after have a report for the first time the present of nontoxic lectin in the legumes *Phaseolus vulgaris* (bean), *Pisum sativum* (pea), *Lens culinaris* (lentil), and *Vicia sativa* (vetch). Following this work more nontoxicity plant hemagglutinin has been found. Eventually, it became Evident that lectin is widespread in the plant kingdom and that toxicity is the

The next milestone in the history of plant lectin was a term. When have been found that some hemagglutinin exhibit a clear preference toward erythrocytes of a particular human blood group within the ABO system (Boyd and Reguera, 1949; and Renkonen, 1948). The term "lectin" originally introduced to emphasize the selective agglutination behavior of some hemagglutinin, it was later applied to all proteins with agglutinating activity. "hemagglutinin" is certainly a more appropriate term than lectin because it refers to the capability of a protein to agglutinate erythrocytes but does not take into account that most lectin can also agglutinate other cells. Hence, the term agglutinin should be preferred. In the absence of a clear consensus, the term lectin is actually most commonly used, but agglutinin

The current confusion in the terminology of lectin to a great degree is result in the fact that different names have been introduced before the mechanism causing the macroscopically visible agglutination activity was understood in molecular terms. In 1936 already observed that cane sugar inhibited the agglutination activity of Concanavalin A (Con A) (Summer and Howell, 1936). It was demonstrated in 1952 that the agglutination properties of lectin is base on a specific sugar-binding activity (Watkins and Morgan, 1952). As soon as lectin was recognized as carbohydrate-binding protein they could be distinguished from other proteins on the basis of a well-defined functional criterion. For this reason lectin is now considered

initially as carbohydrate-binding proteins rather than as (hem) agglutinin.

lectins have been recently reported (Sauerborn et al., 1999; and Wood et al., 1999).

**3. History of plant lectins** 

exception rather than the rule (Van Damme et al., 1995).

and hemagglutinin still persist as synonyms.
