Nigerose is a rare disaccharide composed of two glucose molecules linked by an α-1,3-glycosidic bond. Also known as sakebiose, nigerose occurs naturally as a partial hydrolysis product of nigeran, a polysaccharide found in black molds such as Aspergillus species and in fermenting microorganisms including Leuconostoc mesenteroides. It can also form during glucose caramelization and is present in dextrans derived from rice molds and other sources.

Chemically identified as 3-O-α-D-glucopyranosyl-D-glucose, nigerose exhibits properties such as water solubility, a melting point around 156°C, and a predicted boiling point near 790°C.

Biochemical Characteristics

Nigerose can be synthesized enzymatically by α-glucosidases from fungi such as Aspergillus niger. Through specific transglucosylation reactions—particularly from maltose—the enzyme AgdB, which possesses α-1,3- and α-1,4-glucosidase activity, can produce nigerose as a rare sugar with promising physiological properties. These include potential antioxidant activity, as it has been shown to reduce or prevent the increase of reactive oxygen species (ROS) and malondialdehyde (MDA) in biological systems.

Additionally, nigerose is unfermentable and displays inhibitory effects on certain glycosidase enzymes, making it valuable for designing enzymatic probes and enzyme inhibitors.

Laboratory Production

In research settings, nigerose can be produced enzymatically from abundant carbohydrate sources such as maltose, sucrose, cellobiose, and starch. This is achieved through transglucosylation reactions catalyzed by specific α-glucosidases. Such biocatalytic approaches enable the efficient generation of this rare sugar for biochemical investigations and potential applications in functional foods.

Nigerose is a unique glucose disaccharide featuring an α-1,3-glycosidic linkage. Naturally found in molds and producible through enzymatic synthesis, it holds significant interest in carbohydrate chemistry and enzymology due to its biological activities, antioxidant potential, and inhibitory properties toward glycosidases.