11
non-fermentable by yeast. Schardinger also reported their behavior in the presence
of alcohols, chloroform, ether, and iodine solution. He used the complexes with
these solvents as a means of precipitation of dextrins (Schardinger 1911). This was
the first indication of the ability of dextrins to form “inclusion” complexes (Crini
2014). Finally, Schardinger proposed empirical formulae of dextrins. However, he
did not propose a structure for his crystallized dextrins and also did not attempt their
molecular-weight determinations. It will take another 20 years before the cyclic
nature of Schardinger dextrins will be recognized. Professor Schardinger decided to
stop his research into dextrins in 1911, and as a conclusion he wrote: “I realize that
still very many questions remain unsolved; the answer to these I must leave to
another, who, owing to more favorable external conditions, can deal with the subject
more intensively.”
In the 24 years following Schardinger’s final paper (Schardinger 1911), the field
of research on crystallized dextrins was dominated by the groups of Pringsheim and
Karrer. Pringsheim is recognized as the first researcher to have published prolifically on dextrins. However, the works were repetitive, marred by frequently contradictory results and by even hot debate between the two groups (French 1957a;
Szejtli 1998; Crini 2014; Morin-Crini et al. 2015).
1.3 Historical Landmarks in the Exploration
of Cyclodextrins: From 1911 to 1970
1.3.1 Nomenclature
In 1891, cyclodextrin was initially called cellulosine by Villiers because he assumed
that the novel crystalline substance, obtained from digests of Bacillus amylobacter,
was une sorte de cellulose, i.e., a kind of cellulose (Crini 2014).
In 1903, Schardinger reported the formation of two krystallisiertes dextrins during his investigations of food spoilage, which he called crystallized dextrin A and
crystallized dextrin B, because most of their properties were similar to the already
known partial degradation products of starch, i.e., the dextrins (Schardinger 1903a,
b). One year later, the krystallisiertes dextrins, considered as the intermediate crystallized decomposition products/by-products of starch, were designated by the term
krystallisiertes polysaccharides, i.e., crystallized polysaccharides (Schardinger
1904). Pursuing his investigations on the structure of starch, Schardinger then introduced a distinction between a crystallized amylose for dextrin A and a crystallized
amylodextrin for dextrin B, because, for him, there was an analogy between his
dextrins and amylose and amylodextrin, especially with respect to their iodine color
reactions (Schardinger 1905, 1907). Finally, Schardinger considered that these
names were inappropriate and thus decided to rename it crystallized dextrin-α and
crystallized dextrin-β (Schardinger 1911).
1 History of Cyclodextrins
non-fermentable by yeast. Schardinger also reported their behavior in the presence
of alcohols, chloroform, ether, and iodine solution. He used the complexes with
these solvents as a means of precipitation of dextrins (Schardinger 1911). This was
the first indication of the ability of dextrins to form “inclusion” complexes (Crini
2014). Finally, Schardinger proposed empirical formulae of dextrins. However, he
did not propose a structure for his crystallized dextrins and also did not attempt their
molecular-weight determinations. It will take another 20 years before the cyclic
nature of Schardinger dextrins will be recognized. Professor Schardinger decided to
stop his research into dextrins in 1911, and as a conclusion he wrote: “I realize that
still very many questions remain unsolved; the answer to these I must leave to
another, who, owing to more favorable external conditions, can deal with the subject
more intensively.”
In the 24 years following Schardinger’s final paper (Schardinger 1911), the field
of research on crystallized dextrins was dominated by the groups of Pringsheim and
Karrer. Pringsheim is recognized as the first researcher to have published prolifically on dextrins. However, the works were repetitive, marred by frequently contradictory results and by even hot debate between the two groups (French 1957a;
Szejtli 1998; Crini 2014; Morin-Crini et al. 2015).
1.3 Historical Landmarks in the Exploration
of Cyclodextrins: From 1911 to 1970
1.3.1 Nomenclature
In 1891, cyclodextrin was initially called cellulosine by Villiers because he assumed
that the novel crystalline substance, obtained from digests of Bacillus amylobacter,
was une sorte de cellulose, i.e., a kind of cellulose (Crini 2014).
In 1903, Schardinger reported the formation of two krystallisiertes dextrins during his investigations of food spoilage, which he called crystallized dextrin A and
crystallized dextrin B, because most of their properties were similar to the already
known partial degradation products of starch, i.e., the dextrins (Schardinger 1903a,
b). One year later, the krystallisiertes dextrins, considered as the intermediate crystallized decomposition products/by-products of starch, were designated by the term
krystallisiertes polysaccharides, i.e., crystallized polysaccharides (Schardinger
1904). Pursuing his investigations on the structure of starch, Schardinger then introduced a distinction between a crystallized amylose for dextrin A and a crystallized
amylodextrin for dextrin B, because, for him, there was an analogy between his
dextrins and amylose and amylodextrin, especially with respect to their iodine color
reactions (Schardinger 1905, 1907). Finally, Schardinger considered that these
names were inappropriate and thus decided to rename it crystallized dextrin-α and
crystallized dextrin-β (Schardinger 1911).
1 History of Cyclodextrins