抄録
Rare sugars are defined by the International Society of Rare Sugars as monosaccharides and their
derivatives that are scarce in nature. D-Glucose is the most abundant monosaccharide in nature, and the
other six types including D-fructose and D-galactose, which is a component monosaccharide of lactose,
are abundant in nature. On the other hand, rare sugars exist in small amounts in nature, but there are many
types: 30 types of 6-carbon monosaccharides and sugar alcohols, 14 types of 5-carbon monosaccharides
and sugar alcohols, and 9 types of 4-carbon monosaccharides and sugar alcohols. The production methods
of rare sugars can be divided into chemical synthesis and biological production using enzymes and
microorganisms. In addition, abundant monosaccharides in nature, such as D-glucose, are often used as the
raw materials. Although applications of some of rare sugars have been developed, it is essential to establish
technologies for industrial-scale production to realize their societal implementation. In this review, the
chemical synthesis and biological production of D-allulose, D-allose, D-tagatose, and allitol are described.
