D-Sedoheptulose (sedoheptulose) is a rare naturally-occurring sugar. While glucose is a six-carbon monosaccharide and xylose is a five-carbon monosaccharide, sedoheptulose is unique in being a seven-carbon monosaccharide, which is very rare in nature (Figure 1). Sedoheptulose was discovered in Sedum spectabile in 1917,¹ yet due to its rarity almost no research was carried out on its bioactive properties. It is an interesting question whether or not there is a causal relationship between Sedum spectabile’s desiccation tolerance and the ample amount of sedoheptulose it contains.

Sedoheptulose 7-phosphate, an organophosphate of sedoheptulose, is an intermediate in the pentose phosphate pathway, part of the central metabolism of organisms, and is also an intermediate in the Calvin-Benson pathway, a carbon fixation pathway in photosynthesis, so it fulfills an important role in the metabolism of organisms. Recently, it was found that a sedoheptulose kinase (CARKL) that catalyzes the phosphorylation of sedoheptulose can control the inflammatory immune response through metabolic control (Figure 2).² These results corroborate the existence of a mutually dependent relationship between metabolism and immunity, and further research may show what role sedoheptulose plays in this relationship.