8
and absorbed water without any change in weight. After purification in large amount
of hot water, Villiers obtained small brilliant crystals, most probably β-cyclodextrin,
and determined the chemical composition of this crystalline carbohydrate. He gave
the first empirical formula: [(C 6 H 10 O 5 ) 2 + 3H 2 O]. Its solubility in water at room
temperature was low but raised with temperature. The white crystals with a very
slight sweetness showed extremely high optical activity, much higher than those of
certain dextrins formed under the action of the butyric ferment. Villiers then considered this novel substance as an isomer of starch (Villiers 1891c, d). By manipulating
the experimental conditions, Villiers obtained two distinct crystalline dextrins, most
probably α-cyclodextrin and β-cyclodextrin, having a composition represented by a
multiple of the formula [(C 6 H 10 O 5 ) + 3H 2 O]. Villiers noted again that the white
crystals with a very slight sweetness showed extremely high optical activity.
Pursuing his experiments, he observed that the two dextrins, always considered as
isomers of starch, were almost insoluble in water, soluble in alcohol, nonfermentable, and acid resistant, and they could also be converted into ethers under
the action of acid chlorides. Villiers finally concluded that the properties of these
two particular dextrins were very clearly different from those of the various saccharides and polysaccharides known at the time and proposed the name of cellulosines
due to the similarities with cellulose, e.g., with “regard to difficulty of acid hydrolysis” (Villiers 1891c, d).
At the beginning of the 1900s, Heinrich Robert Koch, a famous German physician and microbiologist, who received a Nobel Prize in 1905, remained unconvinced
by Villiers’ conclusions (Crini 2014). In Koch’s opinion, Villiers used “primitive
bacteriological techniques and probably impure cultures.” This was also pointed out
by Schardinger (1904). Later, French (1957a) indicated that “Villiers used impure
cultures but his digests contained sufficient Bacillus macerans to account for the
small amount of crystalline dextrin obtained.”
The recognition to cyclodextrins is attributed to Franz Schardinger, an Austrian
chemist and bacteriologist. Schardinger is the first Great Scientist who has left its
mark on the history of these oligosaccharides. He is considered the “Founding
Father” of cyclodextrin (Szejtli 1982a; Crini 2014).
At the beginning of the last century, Schardinger also observed the formation of
dextrins during his investigations of resistant microorganisms that can lead to food
poisoning (Fig. 1.4). Like other researchers at that time, Schardinger studied these
dextrins with the expectation that they would shed some light on the synthesis and
degradation of starch. In 1903, Schardinger discovered that a type of extremely
heat-resistant microorganism was able to dissolve starch and form crystalline byproducts (Schardinger 1903a), remarkably similar to cellulosines reported by
Villiers. Using the iodine test, Schardinger distinguished two types of krystallisiertes dextrins which he called crystallized dextrin A and crystallized dextrin B. The
B form resembled Villiers’ cellulosine. Indeed, the chemical behavior and the physical constants given by Schardinger for his substance agree very well with those of
the dextrin previously described by Villiers. Schardinger found that it was possible
to isolate pure fractions with a maximum yield of 30% crystallized dextrins from
starch, the main form obtained being always dextrin B. Krystallisiertes dextrins
N. Morin-Crini et al.
and absorbed water without any change in weight. After purification in large amount
of hot water, Villiers obtained small brilliant crystals, most probably β-cyclodextrin,
and determined the chemical composition of this crystalline carbohydrate. He gave
the first empirical formula: [(C 6 H 10 O 5 ) 2 + 3H 2 O]. Its solubility in water at room
temperature was low but raised with temperature. The white crystals with a very
slight sweetness showed extremely high optical activity, much higher than those of
certain dextrins formed under the action of the butyric ferment. Villiers then considered this novel substance as an isomer of starch (Villiers 1891c, d). By manipulating
the experimental conditions, Villiers obtained two distinct crystalline dextrins, most
probably α-cyclodextrin and β-cyclodextrin, having a composition represented by a
multiple of the formula [(C 6 H 10 O 5 ) + 3H 2 O]. Villiers noted again that the white
crystals with a very slight sweetness showed extremely high optical activity.
Pursuing his experiments, he observed that the two dextrins, always considered as
isomers of starch, were almost insoluble in water, soluble in alcohol, nonfermentable, and acid resistant, and they could also be converted into ethers under
the action of acid chlorides. Villiers finally concluded that the properties of these
two particular dextrins were very clearly different from those of the various saccharides and polysaccharides known at the time and proposed the name of cellulosines
due to the similarities with cellulose, e.g., with “regard to difficulty of acid hydrolysis” (Villiers 1891c, d).
At the beginning of the 1900s, Heinrich Robert Koch, a famous German physician and microbiologist, who received a Nobel Prize in 1905, remained unconvinced
by Villiers’ conclusions (Crini 2014). In Koch’s opinion, Villiers used “primitive
bacteriological techniques and probably impure cultures.” This was also pointed out
by Schardinger (1904). Later, French (1957a) indicated that “Villiers used impure
cultures but his digests contained sufficient Bacillus macerans to account for the
small amount of crystalline dextrin obtained.”
The recognition to cyclodextrins is attributed to Franz Schardinger, an Austrian
chemist and bacteriologist. Schardinger is the first Great Scientist who has left its
mark on the history of these oligosaccharides. He is considered the “Founding
Father” of cyclodextrin (Szejtli 1982a; Crini 2014).
At the beginning of the last century, Schardinger also observed the formation of
dextrins during his investigations of resistant microorganisms that can lead to food
poisoning (Fig. 1.4). Like other researchers at that time, Schardinger studied these
dextrins with the expectation that they would shed some light on the synthesis and
degradation of starch. In 1903, Schardinger discovered that a type of extremely
heat-resistant microorganism was able to dissolve starch and form crystalline byproducts (Schardinger 1903a), remarkably similar to cellulosines reported by
Villiers. Using the iodine test, Schardinger distinguished two types of krystallisiertes dextrins which he called crystallized dextrin A and crystallized dextrin B. The
B form resembled Villiers’ cellulosine. Indeed, the chemical behavior and the physical constants given by Schardinger for his substance agree very well with those of
the dextrin previously described by Villiers. Schardinger found that it was possible
to isolate pure fractions with a maximum yield of 30% crystallized dextrins from
starch, the main form obtained being always dextrin B. Krystallisiertes dextrins
N. Morin-Crini et al.